This document summarizes a research paper on deniable encryption. The paper proposes a receiver-deniable public key encryption scheme with the following properties:
1) It is a one-move scheme that does not require any pre-encryption communication between the sender and receiver.
2) It does not require any pre-shared secrets between parties.
3) It provides strong deniability equivalent to factoring a large composite number.
4) It has no decryption errors.
5) It significantly improves bandwidth efficiency compared to previous schemes.
The proposed scheme uses a mediated RSA infrastructure and relies on oblivious transfer between the receiver and security mediator to enable deniability for the receiver.
Introduction to Public key Cryptosystems with block diagrams
Reference : Cryptography and Network Security Principles and Practice , Sixth Edition , William Stalling
Public key cryptography uses key pairs - a public key and a private key - to encrypt and decrypt messages. The public key can be shared widely, while the private key is kept secret. This allows users to securely share encrypted messages without having to first share secret keys. Common applications of public key cryptography include public key encryption and digital signatures.
CGI White Paper - Key Incryption MechanismAmit Singh
This white paper discusses public key encryption and digital signatures. It begins by defining public key cryptography and explaining how it works using asymmetric key pairs for encryption/decryption and digital signatures. It then discusses how certificates are used to validate identities and keys. Certificates contain a user's public key and identity information, signed by a certificate authority, allowing identities to be verified. The paper also explains how digital signatures, encryption, and certificates are implemented in practice when sending signed and encrypted messages.
This document analyzes the RC4 encryption algorithm and examines how its performance is affected by changing parameters like encryption key length and file size. Experimental tests were conducted to measure encryption time for different key lengths and file types. The results show encryption time increases with longer keys and larger files, and are modeled mathematically. The document also provides background on encryption methods, how RC4 works, and compares stream and block ciphers.
This document summarizes public-key cryptography. It discusses how public-key cryptography uses unique public and private keys to encrypt and decrypt messages securely. It describes how public-key encryption allows a sender to encrypt a message with the recipient's public key, while only the recipient's private key can decrypt it. It also explains how digital signatures allow a sender to encrypt a message with their private key for authentication, while the recipient can decrypt it with the sender's public key to verify identity and integrity. The document notes some vulnerabilities of public-key cryptography like longer key sizes and man-in-the-middle attacks, and how certificate authorities help address these issues.
Blockchain privacy approaches in hyperledger indyManishKumarGiri2
Hyperledger Indy provides privacy-preserving identity solutions using distributed ledger technology. It uses several cryptographic techniques like elliptic curve cryptography, zero-knowledge proofs, and authenticated encryption. Zero-knowledge proofs allow a prover to prove possession of certain information to a verifier without revealing the information itself. Hyperledger Indy implements zero-knowledge proofs using zk-SNARKs and Idemix to privately verify credential information. It also uses Libsodium's sealed boxes for anonymous messaging and credential revocation features to preserve privacy in credentials over time. These approaches help Hyperledger Indy provide private and decentralized identity solutions on blockchains.
Chaos Based Direct Public Verifiable Signcryption SchemeIOSR Journals
This document proposes and describes a chaos-based direct public verifiable signcryption scheme. It begins with background on chaos theory and how chaotic systems can provide useful properties for cryptography. It then discusses signcryption schemes generally and properties they should satisfy like confidentiality, integrity, and public verifiability. The document proposes a new signcryption scheme that uses a chaotic key generator and the chaotic function f(x) = 3x(1-x^2) to dynamically generate multiple encryption keys, aiming to provide stronger security. It presents the scheme details, including parameters, key generation, and how it can realize single-recipient and multiple-recipient signcryption with public verifiability. The scheme is then analyzed for
Introduction to Public key Cryptosystems with block diagrams
Reference : Cryptography and Network Security Principles and Practice , Sixth Edition , William Stalling
Public key cryptography uses key pairs - a public key and a private key - to encrypt and decrypt messages. The public key can be shared widely, while the private key is kept secret. This allows users to securely share encrypted messages without having to first share secret keys. Common applications of public key cryptography include public key encryption and digital signatures.
CGI White Paper - Key Incryption MechanismAmit Singh
This white paper discusses public key encryption and digital signatures. It begins by defining public key cryptography and explaining how it works using asymmetric key pairs for encryption/decryption and digital signatures. It then discusses how certificates are used to validate identities and keys. Certificates contain a user's public key and identity information, signed by a certificate authority, allowing identities to be verified. The paper also explains how digital signatures, encryption, and certificates are implemented in practice when sending signed and encrypted messages.
This document analyzes the RC4 encryption algorithm and examines how its performance is affected by changing parameters like encryption key length and file size. Experimental tests were conducted to measure encryption time for different key lengths and file types. The results show encryption time increases with longer keys and larger files, and are modeled mathematically. The document also provides background on encryption methods, how RC4 works, and compares stream and block ciphers.
This document summarizes public-key cryptography. It discusses how public-key cryptography uses unique public and private keys to encrypt and decrypt messages securely. It describes how public-key encryption allows a sender to encrypt a message with the recipient's public key, while only the recipient's private key can decrypt it. It also explains how digital signatures allow a sender to encrypt a message with their private key for authentication, while the recipient can decrypt it with the sender's public key to verify identity and integrity. The document notes some vulnerabilities of public-key cryptography like longer key sizes and man-in-the-middle attacks, and how certificate authorities help address these issues.
Blockchain privacy approaches in hyperledger indyManishKumarGiri2
Hyperledger Indy provides privacy-preserving identity solutions using distributed ledger technology. It uses several cryptographic techniques like elliptic curve cryptography, zero-knowledge proofs, and authenticated encryption. Zero-knowledge proofs allow a prover to prove possession of certain information to a verifier without revealing the information itself. Hyperledger Indy implements zero-knowledge proofs using zk-SNARKs and Idemix to privately verify credential information. It also uses Libsodium's sealed boxes for anonymous messaging and credential revocation features to preserve privacy in credentials over time. These approaches help Hyperledger Indy provide private and decentralized identity solutions on blockchains.
Chaos Based Direct Public Verifiable Signcryption SchemeIOSR Journals
This document proposes and describes a chaos-based direct public verifiable signcryption scheme. It begins with background on chaos theory and how chaotic systems can provide useful properties for cryptography. It then discusses signcryption schemes generally and properties they should satisfy like confidentiality, integrity, and public verifiability. The document proposes a new signcryption scheme that uses a chaotic key generator and the chaotic function f(x) = 3x(1-x^2) to dynamically generate multiple encryption keys, aiming to provide stronger security. It presents the scheme details, including parameters, key generation, and how it can realize single-recipient and multiple-recipient signcryption with public verifiability. The scheme is then analyzed for
This document summarizes and analyzes several signcryption schemes based on elliptic curves. Signcryption allows for both encryption and digital signing to be performed in one logical step, reducing computational costs compared to traditional signature-then-encryption schemes. The document analyzes schemes by Zheng and Imai, Bao & Deng, Gamage et al, and Jung et al in terms of security goals achieved, communication overhead, and computational costs. It finds that while all schemes achieve confidentiality, integrity, and unforgeability, they differ in supporting features like forward secrecy and public verification. The Zheng & Imai scheme has the lowest computational costs but lacks forward secrecy and public verification.
Key Distribution Problem in advanced operating systemMerlin Florrence
The document discusses the key distribution problem in cryptography. When two entities want to securely communicate, they must obtain matching encryption and decryption keys. There are different approaches to key distribution, including a centralized approach where a single Key Distribution Center (KDC) maintains secret keys for each user, and a fully distributed approach without a central authority. The centralized approach is simple to implement but relies on a single point of failure.
A digital signature allows one to verify the identity of the sender of a message and that the message content has not been altered. It involves a key generation algorithm that produces a private key and public key pair. The signing algorithm uses the private key to generate a signature for a message. The signature verification algorithm uses the public key to verify the signature and authenticity of the message. Digital signatures provide security as long as the private key remains confidential to the owner.
The document proposes an efficient generalized signcryption scheme based on elliptic curve cryptography (ECC) that avoids computationally heavy bilinear pairing operations. It first identifies security issues in a previous tripartite signcryption scheme and proposes corrections. The corrected scheme is extended to support multiple receivers. It then further extends this signcryption scheme to a generalized signcryption scheme that provides either confidentiality, authentication, or a combination of both for messages with multiple receivers. The proposed schemes use only ECC operations and satisfy security properties like forward secrecy and public verification more efficiently than other existing schemes. An application of the generalized signcryption scheme for key management in wireless sensor networks is also discussed.
Cryptography is an essential part of today's information systems and helps provide security, accountability, and confidentiality. There are three main types of cryptographic algorithms: secret key cryptography which uses a single key, public key cryptography which uses different keys for encryption and decryption, and hash functions which use a mathematical transformation to encrypt information. A hybrid cryptographic scheme combines these techniques to securely transmit messages with a digital envelope for encryption and a digital signature for authentication and integrity.
1 Symmetric Encryption
2 Message Authentication and Hash Functions
3 Public-Key Encryption
4 Digital Signatures and Key Management
5 Random and Pseudo random Numbers
6 Practical Application: Encryption of Stored Data
7 Symmetric vs Asymmetric
The document describes a thesis submitted by Amogh Mahapatra and Rajballav Dash for their Bachelor of Technology degree. It examines using the Hill cipher technique and self-repetitive matrices for data encryption and decryption. Specifically, it proposes an innovation to the conventional Hill cipher method using the concept of self-repetitive matrices. This approach is mathematically derived and implemented to simulate a communication channel with compression techniques. The method aims to address issues with inverting the Hill cipher's multiplicative matrix by using periodically repeating matrices.
The document discusses authentication protocols and digital signatures. It describes mutual authentication protocols that allow two parties to verify each other's identities and exchange session keys. It also discusses one-way authentication protocols. The document focuses on explaining the Digital Signature Standard (DSS) and the Digital Signature Algorithm (DSA). It provides details on how DSA uses public/private key pairs to generate and verify digital signatures for authenticating messages and senders.
AN EFFICIENT PROXY SIGNCRYPTION SCHEME BASED ON THE DISCRETE LOGARITHM PROBLEMZac Darcy
This document proposes a new efficient proxy signcryption scheme based on the discrete logarithm problem (DLP). The scheme allows an original signer to delegate signing power to a proxy signer, who can then sign messages on behalf of the original signer. The scheme consists of setup, proxy-credential-generation, proxy-signcryption-generation, and proxy-unsigncryption-verification phases. It achieves security requirements like verifiability, unforgeability, identifiability, and prevention of misuse through use of public/private keys and the intractability of computing discrete logarithms. The scheme is proven correct and its security is analyzed.
This document provides an overview of information security and cryptography. It discusses objectives of security like avoiding data threats. It also covers topics like password auditing, data security, authentication, encryption, decryption, public and private key cryptography, digital signatures, and the RSA algorithm. It demonstrates an example of encrypting a message using RSA and decrypting the cipher text. The conclusion emphasizes the importance of information security.
Advanced cryptography and implementationAkash Jadhav
The document discusses a technical presentation on advanced cryptography and its implementation. It provides an overview of cryptography, including its history and basic concepts such as encryption, decryption, and cryptanalysis. Examples of cryptography applications discussed include ATM cards, credit cards, e-mail, and lottery tickets.
This document discusses the OSI security architecture and its key concepts of security attacks, mechanisms, and services. It defines security attacks as any action compromising information security, security mechanisms as tools to detect, prevent or recover from attacks, and security services as services enhancing security. The document then discusses common types of security attacks like passive attacks involving unauthorized access and active attacks involving modifying information. It also outlines various cryptographic attacks against cryptosystems like ciphertext-only, known plaintext, chosen plaintext, and brute force attacks. Finally, it describes the main security services provided by cryptography as confidentiality, data integrity, authentication, and non-repudiation.
Digital signatures provide authentication of digital documents through encryption with a private key. They offer advantages over physical signatures like non-repudiation and integrity verification by checking that the document contents have not changed. Digital signatures are created by running a hash function over a message to generate a message digest, then encrypting the digest with a private key. They can be used for a variety of applications including e-voting, online money transfers, and filing government forms electronically.
This document provides an overview of network security and cryptography. It discusses the history and basic concepts of networking and security. The document covers risk management, network threats like viruses and denial of service attacks. It also explains different network security methods like virtual private networks (VPNs), firewalls, and IPSec. Cryptography techniques like secret key cryptography, public key cryptography, hash functions, and authentication methods are summarized. Popular cryptographic algorithms and protocols like PGP, SHA, and AAA servers are also mentioned.
The document provides a specification for the Silent Circle Instant Messaging Protocol (SCIMP). SCIMP enables private conversations over instant messaging and draws from related protocols like ZRTP, OTR, and Cryptocat. It provides strong encryption, authentication, and perfect forward secrecy using algorithms approved by NIST like ECCDH, AES, and SHA. The protocol establishes an encrypted session in 3 messages using key continuity and optional voice verification to prevent man-in-the-middle attacks. It then encrypts messages with CCM authenticated encryption.
Secrecy and Authenticity Properties of the Lightning Network ProtocolHans Hyttel
The document analyzes the security properties of the Lightning Network protocol using the ProVerif tool. It describes the key agreement protocol used to establish secure connections between nodes. ProVerif is used to verify that the session keys generated during key agreement are kept secret. It also checks that the protocol satisfies authenticity properties by ensuring initiated connections are correctly associated with participants. The analysis shows the session keys are secret but authenticity of initiated connections is only guaranteed for responding nodes, not initiating nodes.
Cryptography is used to protect information by encrypting messages into an unreadable cipher text format. Modern cryptography uses either secret key cryptography, which uses a single key for encryption and decryption, or public key cryptography, which uses two mathematically related keys with one key to encrypt and the other to decrypt. The purpose of cryptography and security is to defend against hackers, industrial espionage, and to secure e-commerce, bank accounts, intellectual property, and avoid liability.
This document proposes a new method for obtaining digital signatures using an RSA algorithm. It introduces digital signatures and their features. The existing RSA algorithm and the proposed multiple integer RSA algorithm are described. The software, hardware, and working applications to generate and view signatures are outlined. Test results showing the proposed method has faster execution times are presented. The document concludes the proposed method authenticates identity and ensures integrity while providing high security. Future work to improve digital signature storage and replace external devices is discussed.
Lecture 9 key distribution and user authentication rajakhurram
1. The document discusses two main methods for key distribution: symmetric key distribution using symmetric encryption like Kerberos, and key distribution using asymmetric encryption like X.509 certificates.
2. It provides an overview of how symmetric key distribution works in Kerberos, including the use of a key distribution center and ticket granting tickets.
3. It also summarizes X.509 certificates, how they are issued by a certificate authority with a user's public key and signature, and how they can be used to verify a user's identity.
A Proxy signature scheme enables a proxy signer to sign a message on behalf of
the original signer. In this paper, we propose ECDLP based solution for chen et. al [1]
scheme. We describe efficient and secure Proxy multi signature scheme that satisfy all the
proxy requirements and require only elliptic curve multiplication and elliptic curve addition
which needs less computation overhead compared to modular exponentiations also our
scheme is withstand against original signer forgery and public key substitution attack.
An Effective Heuristic Approach for Hiding Sensitive Patterns in DatabasesIOSR Journals
The document presents an algorithm for sanitizing a database to hide sensitive patterns while minimizing changes to the original data. It identifies sensitive transactions containing restrictive patterns to be hidden and sorts them by degree and size. It then selects items with the maximum cover across restrictive patterns and removes them from sensitive transactions, reducing support for the patterns. This process iterates until restrictive pattern support is reduced to 0. The sanitized database combines modified sensitive transactions with unmodified non-sensitive transactions. The algorithm is tested on sample databases to evaluate effectiveness with minimal impact on the original data.
Allelopathic effect of Albizia saman F. Muell on three widely cultivated Indi...IOSR Journals
- The study assessed the allelopathic effect of Albizia saman leaf leachate on three crop species: Amaranthus viridis (vegetable), Brassica campestris (oil), and Oryza sativa (cereal).
- Germination and seedling growth were inhibited in Amaranthus and Brassica with increasing leachate concentration, with Brassica being most sensitive. Germination of Oryza was not affected.
- Root growth was more sensitive than shoot/hypocotyl growth. Oryza was more tolerant to the allelopathic effects than the other species. The study showed that Albizia saman leaf leachate has inhibitory
This document summarizes and analyzes several signcryption schemes based on elliptic curves. Signcryption allows for both encryption and digital signing to be performed in one logical step, reducing computational costs compared to traditional signature-then-encryption schemes. The document analyzes schemes by Zheng and Imai, Bao & Deng, Gamage et al, and Jung et al in terms of security goals achieved, communication overhead, and computational costs. It finds that while all schemes achieve confidentiality, integrity, and unforgeability, they differ in supporting features like forward secrecy and public verification. The Zheng & Imai scheme has the lowest computational costs but lacks forward secrecy and public verification.
Key Distribution Problem in advanced operating systemMerlin Florrence
The document discusses the key distribution problem in cryptography. When two entities want to securely communicate, they must obtain matching encryption and decryption keys. There are different approaches to key distribution, including a centralized approach where a single Key Distribution Center (KDC) maintains secret keys for each user, and a fully distributed approach without a central authority. The centralized approach is simple to implement but relies on a single point of failure.
A digital signature allows one to verify the identity of the sender of a message and that the message content has not been altered. It involves a key generation algorithm that produces a private key and public key pair. The signing algorithm uses the private key to generate a signature for a message. The signature verification algorithm uses the public key to verify the signature and authenticity of the message. Digital signatures provide security as long as the private key remains confidential to the owner.
The document proposes an efficient generalized signcryption scheme based on elliptic curve cryptography (ECC) that avoids computationally heavy bilinear pairing operations. It first identifies security issues in a previous tripartite signcryption scheme and proposes corrections. The corrected scheme is extended to support multiple receivers. It then further extends this signcryption scheme to a generalized signcryption scheme that provides either confidentiality, authentication, or a combination of both for messages with multiple receivers. The proposed schemes use only ECC operations and satisfy security properties like forward secrecy and public verification more efficiently than other existing schemes. An application of the generalized signcryption scheme for key management in wireless sensor networks is also discussed.
Cryptography is an essential part of today's information systems and helps provide security, accountability, and confidentiality. There are three main types of cryptographic algorithms: secret key cryptography which uses a single key, public key cryptography which uses different keys for encryption and decryption, and hash functions which use a mathematical transformation to encrypt information. A hybrid cryptographic scheme combines these techniques to securely transmit messages with a digital envelope for encryption and a digital signature for authentication and integrity.
1 Symmetric Encryption
2 Message Authentication and Hash Functions
3 Public-Key Encryption
4 Digital Signatures and Key Management
5 Random and Pseudo random Numbers
6 Practical Application: Encryption of Stored Data
7 Symmetric vs Asymmetric
The document describes a thesis submitted by Amogh Mahapatra and Rajballav Dash for their Bachelor of Technology degree. It examines using the Hill cipher technique and self-repetitive matrices for data encryption and decryption. Specifically, it proposes an innovation to the conventional Hill cipher method using the concept of self-repetitive matrices. This approach is mathematically derived and implemented to simulate a communication channel with compression techniques. The method aims to address issues with inverting the Hill cipher's multiplicative matrix by using periodically repeating matrices.
The document discusses authentication protocols and digital signatures. It describes mutual authentication protocols that allow two parties to verify each other's identities and exchange session keys. It also discusses one-way authentication protocols. The document focuses on explaining the Digital Signature Standard (DSS) and the Digital Signature Algorithm (DSA). It provides details on how DSA uses public/private key pairs to generate and verify digital signatures for authenticating messages and senders.
AN EFFICIENT PROXY SIGNCRYPTION SCHEME BASED ON THE DISCRETE LOGARITHM PROBLEMZac Darcy
This document proposes a new efficient proxy signcryption scheme based on the discrete logarithm problem (DLP). The scheme allows an original signer to delegate signing power to a proxy signer, who can then sign messages on behalf of the original signer. The scheme consists of setup, proxy-credential-generation, proxy-signcryption-generation, and proxy-unsigncryption-verification phases. It achieves security requirements like verifiability, unforgeability, identifiability, and prevention of misuse through use of public/private keys and the intractability of computing discrete logarithms. The scheme is proven correct and its security is analyzed.
This document provides an overview of information security and cryptography. It discusses objectives of security like avoiding data threats. It also covers topics like password auditing, data security, authentication, encryption, decryption, public and private key cryptography, digital signatures, and the RSA algorithm. It demonstrates an example of encrypting a message using RSA and decrypting the cipher text. The conclusion emphasizes the importance of information security.
Advanced cryptography and implementationAkash Jadhav
The document discusses a technical presentation on advanced cryptography and its implementation. It provides an overview of cryptography, including its history and basic concepts such as encryption, decryption, and cryptanalysis. Examples of cryptography applications discussed include ATM cards, credit cards, e-mail, and lottery tickets.
This document discusses the OSI security architecture and its key concepts of security attacks, mechanisms, and services. It defines security attacks as any action compromising information security, security mechanisms as tools to detect, prevent or recover from attacks, and security services as services enhancing security. The document then discusses common types of security attacks like passive attacks involving unauthorized access and active attacks involving modifying information. It also outlines various cryptographic attacks against cryptosystems like ciphertext-only, known plaintext, chosen plaintext, and brute force attacks. Finally, it describes the main security services provided by cryptography as confidentiality, data integrity, authentication, and non-repudiation.
Digital signatures provide authentication of digital documents through encryption with a private key. They offer advantages over physical signatures like non-repudiation and integrity verification by checking that the document contents have not changed. Digital signatures are created by running a hash function over a message to generate a message digest, then encrypting the digest with a private key. They can be used for a variety of applications including e-voting, online money transfers, and filing government forms electronically.
This document provides an overview of network security and cryptography. It discusses the history and basic concepts of networking and security. The document covers risk management, network threats like viruses and denial of service attacks. It also explains different network security methods like virtual private networks (VPNs), firewalls, and IPSec. Cryptography techniques like secret key cryptography, public key cryptography, hash functions, and authentication methods are summarized. Popular cryptographic algorithms and protocols like PGP, SHA, and AAA servers are also mentioned.
The document provides a specification for the Silent Circle Instant Messaging Protocol (SCIMP). SCIMP enables private conversations over instant messaging and draws from related protocols like ZRTP, OTR, and Cryptocat. It provides strong encryption, authentication, and perfect forward secrecy using algorithms approved by NIST like ECCDH, AES, and SHA. The protocol establishes an encrypted session in 3 messages using key continuity and optional voice verification to prevent man-in-the-middle attacks. It then encrypts messages with CCM authenticated encryption.
Secrecy and Authenticity Properties of the Lightning Network ProtocolHans Hyttel
The document analyzes the security properties of the Lightning Network protocol using the ProVerif tool. It describes the key agreement protocol used to establish secure connections between nodes. ProVerif is used to verify that the session keys generated during key agreement are kept secret. It also checks that the protocol satisfies authenticity properties by ensuring initiated connections are correctly associated with participants. The analysis shows the session keys are secret but authenticity of initiated connections is only guaranteed for responding nodes, not initiating nodes.
Cryptography is used to protect information by encrypting messages into an unreadable cipher text format. Modern cryptography uses either secret key cryptography, which uses a single key for encryption and decryption, or public key cryptography, which uses two mathematically related keys with one key to encrypt and the other to decrypt. The purpose of cryptography and security is to defend against hackers, industrial espionage, and to secure e-commerce, bank accounts, intellectual property, and avoid liability.
This document proposes a new method for obtaining digital signatures using an RSA algorithm. It introduces digital signatures and their features. The existing RSA algorithm and the proposed multiple integer RSA algorithm are described. The software, hardware, and working applications to generate and view signatures are outlined. Test results showing the proposed method has faster execution times are presented. The document concludes the proposed method authenticates identity and ensures integrity while providing high security. Future work to improve digital signature storage and replace external devices is discussed.
Lecture 9 key distribution and user authentication rajakhurram
1. The document discusses two main methods for key distribution: symmetric key distribution using symmetric encryption like Kerberos, and key distribution using asymmetric encryption like X.509 certificates.
2. It provides an overview of how symmetric key distribution works in Kerberos, including the use of a key distribution center and ticket granting tickets.
3. It also summarizes X.509 certificates, how they are issued by a certificate authority with a user's public key and signature, and how they can be used to verify a user's identity.
A Proxy signature scheme enables a proxy signer to sign a message on behalf of
the original signer. In this paper, we propose ECDLP based solution for chen et. al [1]
scheme. We describe efficient and secure Proxy multi signature scheme that satisfy all the
proxy requirements and require only elliptic curve multiplication and elliptic curve addition
which needs less computation overhead compared to modular exponentiations also our
scheme is withstand against original signer forgery and public key substitution attack.
An Effective Heuristic Approach for Hiding Sensitive Patterns in DatabasesIOSR Journals
The document presents an algorithm for sanitizing a database to hide sensitive patterns while minimizing changes to the original data. It identifies sensitive transactions containing restrictive patterns to be hidden and sorts them by degree and size. It then selects items with the maximum cover across restrictive patterns and removes them from sensitive transactions, reducing support for the patterns. This process iterates until restrictive pattern support is reduced to 0. The sanitized database combines modified sensitive transactions with unmodified non-sensitive transactions. The algorithm is tested on sample databases to evaluate effectiveness with minimal impact on the original data.
Allelopathic effect of Albizia saman F. Muell on three widely cultivated Indi...IOSR Journals
- The study assessed the allelopathic effect of Albizia saman leaf leachate on three crop species: Amaranthus viridis (vegetable), Brassica campestris (oil), and Oryza sativa (cereal).
- Germination and seedling growth were inhibited in Amaranthus and Brassica with increasing leachate concentration, with Brassica being most sensitive. Germination of Oryza was not affected.
- Root growth was more sensitive than shoot/hypocotyl growth. Oryza was more tolerant to the allelopathic effects than the other species. The study showed that Albizia saman leaf leachate has inhibitory
Ab Initio Study of the Electronic and Phonon Band Structure Of the Mixed Vale...IOSR Journals
This document summarizes an ab initio study of the electronic band structure and phonon dispersion of silver oxide (AgO) using density functional theory calculations. The LDA+U method predicted AgO to be a semimetal, while the Hartree-Fock calculation predicted a semiconductor with an indirect bandgap of 1.53 eV, consistent with experiments. Phonon calculations showed small splitting between longitudinal and transverse optical modes for higher oxygen vibrations, explaining why Raman spectroscopy could not observe these modes. The study provides insights into the electronic properties and vibrational behavior of the mixed valence silver oxide.
Performance of Web Services on Smart Phone PlatformsIOSR Journals
This document discusses and compares the performance of Web Services on smart phone platforms using SOAP and REST. It begins with an introduction to Web Services and the problems with using SOAP on mobile devices due to its limitations in processing power, bandwidth usage, and flexibility. It then proposes using RESTful Web Services as an alternative as they avoid XML parsing and are based on the lightweight HTTP protocol. The document analyzes the performance of SOAP versus REST Web Services on a mobile device to determine which is more efficient for smart phones.
The document evaluates the performance of 5 routing protocols (AODV, DSR, TORA, OLSR, GRP) in a mobile ad hoc network (MANET) using the OPNET simulator. Simulations were run with 30, 60, and 90 nodes using email and video conferencing applications. Performance was analyzed based on throughput, delay, load, and data dropped. In general, GRP and OLSR had the lowest delay, DSR and GRP had the lowest load, and OLSR and AODV had the highest throughput, while TORA often had the worst performance based on the metrics. The evaluation provides insights into the relative performance of the routing protocols under different conditions in a MANET
A Survey on Network Layer Multicast Routing Protocols for Mobile Ad Hoc Netw...IOSR Journals
This document summarizes a survey on network layer multicast routing protocols for mobile ad hoc networks. It begins with an introduction to multicast routing in MANETs and their advantages over unicast. It then provides an overview of the architecture for multicast routing protocols, which consists of three layers: the MAC, routing, and application layers. The document classifies and discusses issues with designing multicast protocols for MANETs. It also categorizes existing multicast routing protocols based on the structure they construct (tree or mesh based), how sessions are initialized (source or receiver initiated), and how topology is maintained (proactively or reactively). Several example protocols are described briefly, including MAODV, AMRIS, and
Comparison of different Ant based techniques for identification of shortest p...IOSR Journals
This document compares different ant colony optimization (ACO) techniques for identifying the shortest path in a distributed network. ACO is based on the behavior of ants finding food sources and uses pheromone trails to probabilistically determine paths. The document reviews several ACO algorithms and techniques, including Max-Min, rank-based, and fuzzy rule-based approaches. It then implements an efficient ACO algorithm that performs better at finding the shortest path compared to other existing ACO techniques.
This document summarizes the results of chemical analysis of two types of freshwater macroalgae, Chara sp. and Spirogyra, collected from Bestansur Village in Iraq. High performance liquid chromatography (HPLC) was used to identify and quantify various chemical constituents. HPLC analysis found that both algae contained alkaloids like kaempfertin, isoquinoline, corilagin and colocynthitin. Spirogyra also contained gallic acid. Both algae contained five steroid compounds and Chara sp. was found to contain high levels of tocopherols like alpha-tocopherol. Inductively coupled plasma analysis also identified various elements in the algae
A Solution to Optimal Power Flow Problem using Artificial Bee Colony Algorith...IOSR Journals
This document presents an artificial bee colony (ABC) algorithm approach to solve the optimal power flow (OPF) problem incorporating a flexible AC transmission system (FACTS) device, specifically a static synchronous series compensator (SSSC). The ABC algorithm is tested on the IEEE 14-bus test system both with and without the SSSC. Results show that the ABC algorithm gives a better solution when incorporating the SSSC, improving the system performance in terms of lower total cost, lower power losses, and better voltage profile compared to the case without SSSC.
An Efficient Biological Sequence Compression Technique Using LUT and Repeat ...IOSR Journals
This document presents two improved biological sequence compression algorithms that utilize a lookup table (LUT) and identification of tandem repeats in sequences. The first algorithm maps all possible 3-character combinations to ASCII characters using a 125-entry LUT. The second maps all possible 4-character combinations to ASCII characters using a 256-entry LUT. These algorithms aim to achieve high compression factors, saving percentages, and faster compression/decompression times compared to previous biological sequence compression methods.
Disposition Pattern of Sulphur Functional Groups in High Sulphur Ledo Coals o...IOSR Journals
This document discusses a study of the distribution of sulfur functional groups in high-sulfur Ledo coals from Assam, India using Temperature Programmed Reduction (TPR). TPR studies were conducted on Ledo coal and model sulfur compounds between 190-6200°C in hydrogen gas. Six hydrogen sulfide evolutions were observed from Ledo coal, which were assigned to specific sulfur functional groups based on the TPR results from model compounds. These included mercaptan/disulfide, thiol, aromatic thioether, thiophene, pyrite, and complex thiophene groups. Additional experiments estimated the thioketonic sulfur content in Ledo coal to be 1.59%. Infrared spectroscopy was also used
Transient Stability Enhancement of Grid by Using Fuzzy Logic Based StatcomIOSR Journals
This document discusses enhancing transient stability of the power grid using a fuzzy logic controlled static synchronous compensator (STATCOM). A STATCOM regulates voltage by injecting or absorbing reactive power. It consists of a voltage source converter, control unit, and DC capacitor. The control unit uses fuzzy logic control, abc to dq transformation, phase locked loop, and regulators to control the STATCOM terminal voltage and maintain the grid voltage during transients. Simulations show the fuzzy logic controller provides faster response and is more robust than a PI controller. Detailed explanations are provided of the STATCOM components and control techniques.
A Fast Recognition Method for Pose and Illumination Variant Faces on Video Se...IOSR Journals
This document summarizes a research paper that proposes a new face recognition method for video sequences with variations in pose and illumination. The proposed method uses an active appearance model without nonlinear programming to extract features, and a lazy classifier for recognition, in order to reduce computational complexity compared to previous methods. Experimental results show the proposed method achieves better recognition performance and lower computational cost than conventional techniques. The document provides background on video face recognition challenges and reviews related work on pose-invariant and illumination-robust recognition methods.
Proximate Composition of Whole Seeds and Pulp of African Black Velvet Tamarin...IOSR Journals
The document analyzes the proximate composition of whole seeds and pulp from the African black velvet tamarind (Dialium guineense). Analysis found higher levels of dry matter, crude fat, crude fiber, protein, and nitrogen in the whole seeds compared to the pulp. Conversely, the pulp contained higher levels of moisture, ash, organic matter, and carbohydrates. Mineral analysis found higher levels of magnesium, sodium, iron, and potassium in the pulp, while calcium was higher in the whole seeds. The results suggest the whole seeds and pulp can serve as good sources of essential nutrients for humans and livestock.
Temperature and Azimuth angle variation effect on the Building Integrated Pho...IOSR Journals
This document analyzes the effects of temperature and azimuth angle variation on power generation from building integrated photovoltaic systems in Bangladesh. It finds that power output increases by around 10.05% when the tilt/azimuth angle is varied from 21°/180° to 21°/0° at a temperature of 30°C, taking into account Bangladesh's climate. It also examines how solar irradiation and the maximum voltage and current from a photovoltaic module vary over the course of a day. The power generation characteristics of two photovoltaic arrays are characterized considering variations in temperature and azimuth angle.
The document summarizes a study on the effects of sowing date and crop spacing on growth, yield attributes, and quality of sesame. The study found that sowing early in the second fortnight of February and using a rectangular spacing of 45 x 15 cm resulted in superior performance of the sesame variety KS 95010. This combination led to taller plants, higher leaf area index, more branches, capsules, and seeds per plant. It also resulted in higher test weight, seed yield of 908 kg/ha, net income of 19,801 rupees, and a benefit-cost ratio of 3.09. The optimal plant density and spacing of 45 x 15 cm allowed for better resource utilization and maxim
Computational Method for Forensic Verification of offline SignaturesIOSR Journals
This document proposes a computational method for forensic verification of offline signatures based on a forensic document examination approach. The method extracts six signature features including slant, size, alignment, spacing, angle of strokes, and aspect ratio based on pixel values and coordinate geometry. These features are then used to classify 150 signatures from 100 control samples and 50 suspected forgeries. The method achieved an average accuracy of 96.7% for control signatures and 94.5% for suspected signatures, providing a more accurate and efficient verification approach compared to models requiring large signature databases.
Video Streaming Compression for Wireless Multimedia Sensor NetworksIOSR Journals
This document discusses video streaming compression for wireless multimedia sensor networks. It proposes a cross-layer system that jointly controls the video encoding rate, transmission rate, and uses an adaptive parity scheme. At the application layer, video is compressed and divided into packets. These packets are encoded at the transport layer and forwarded through the network layer. An active buffer management scheme and adaptive parity check are used to maximize received video quality over lossy wireless links. Simulation results show the proposed techniques can achieve higher throughput by resequencing dropped packets. The goal is to design an efficient system for wireless transmission of compressed video that optimizes video quality.
Analysis of Rayleigh Quotient in Extrapolation Method to Accelerate the Compu...IOSR Journals
This document describes research analyzing the use of Rayleigh quotients to accelerate the computation speed of PageRank. It begins with background on PageRank, extrapolation methods, and Rayleigh quotients. The research aims to combine Rayleigh quotients with an extrapolation method to speed up PageRank calculations. Experiments were conducted on datasets from Stanford and Toronto universities using Matlab. The results showed that incorporating Rayleigh quotients into the extrapolation method accelerated the computation speed of PageRank.
Automatic Learning Image Objects via Incremental ModelIOSR Journals
This document presents a novel approach for automatically collecting and learning object category datasets and models in an incremental manner by leveraging web image resources. The proposed framework uses object recognition techniques to iteratively accumulate model knowledge and image examples, mimicking human learning. An incremental learning algorithm is used to automatically collect larger object category datasets than existing datasets like Caltech 101. As new images are classified and added in each iteration, the object model becomes more robust, leading to an even larger and more accurate collected dataset. Experiments show the approach is effective at collecting superior image datasets compared to existing resources.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
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The research of the digital certified mail up to implementing the base algorithm and then, go through more on pretty good privacy (PGP) applied to the email system.
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Confidentiality & Authentication Mechanism for Biometric Information Transmit...IJNSA Journal
The security of bio-metric information – finger print, retina mapping, DNA mapping and some other chemical and biological modified genes related information - transfer through low bandwidth and unreliable or covert channel is challenging task. Therefore, Security of biometric information is essential requirement in this fast developing communication world. Thus, in this paper, we propose efficient and effective mechanism for confidentiality and authentication for biometric information transmitted by using arithmetic encoding representation over low bandwidth and unreliable channel. It enhances the speed of encryption, decryption and authentication process. It uses arithmetic encoding scheme and public key cryptography e.g. modified version of RSA algorithm called RSA-2 algorithm.
The document discusses the RSA algorithm and its implementation in SSL-VPN architectures. It begins by introducing SSL-VPN and how it uses the RSA algorithm. It then provides a high-level overview of the mathematical concepts behind the RSA algorithm, including generating public and private key pairs using large prime numbers. It also describes how the RSA algorithm is used for encryption and decryption in SSL-VPN systems to securely transmit encrypted data between private networks over the internet.
Module 2 Lectures 4 hrs.
Cryptography and Cryptanalysis: Introduction to Cryptography, Symmetric key
Cryptography, Asymmetric key Cryptography, Message Authentication, Digital Signatures,
Applications of Cryptography. Overview of Firewalls- Types of Firewalls, User
Management, VPN Security, Security Protocols: - security at the Application Layer- PGP
and S/MIME, Security at Transport Layer- SSL and TLS, Security at Network Layer-IPSec.
Open Source/ Free/ Trial Tools: Implementation of Cryptographic techniques, OpenSSL,
Hash
Values Calculations MD5, SHA1, SHA256, SHA 512, Steganography (Stools)
This document provides an overview of cyber security topics including cryptography, cryptanalysis, symmetric and asymmetric key cryptography, hashing, digital signatures, firewalls, user management, and virtual private networks (VPNs). It defines these terms and concepts, compares different techniques like symmetric vs asymmetric cryptography, and packet filtering vs stateful inspection firewalls. The document also discusses the importance of using firewalls and how VPNs can provide privacy and anonymity online.
http://www.skyriver.net/ - Skyriver Communications – Fixed Wireless Security. Skyriver is a leading business ISP, specializing in Fixed Wireless. Learn about Skyrivers’ innovative high performance broadband for business visit the site now.
Public key cryptography uses asymmetric encryption with two related keys - a public key and a private key. The public key can be shared openly but the private key is kept secret. When Alice wants to send a confidential message to Bob, she encrypts it with Bob's public key. Only Bob can decrypt it using his private key. Public key infrastructure involves policies and technologies for issuing, managing, and revoking digital certificates that bind public keys to identities. Popular public key algorithms like RSA are based on the difficulty of factoring large prime numbers.
Principles of public key cryptography and its UsesMohsin Ali
This document discusses the principles of public key cryptography. It begins by defining asymmetric encryption and how it uses a public key and private key instead of a single shared key. It then discusses key concepts like digital certificates and public key infrastructure. The document also provides examples of how public key cryptography can be used, including the RSA algorithm and key distribution methods like public key directories and certificates. It explains how public key cryptography solves the key distribution problem present in symmetric encryption.
A new hybrid text encryption approach over mobile ad hoc network IJECEIAES
This document summarizes a research paper that proposes a new hybrid text encryption approach combining elliptic curve cryptography and the Hill cipher algorithm for use on mobile ad hoc networks. The approach aims to address security weaknesses in the Hill cipher by converting it from a symmetric to an asymmetric technique. It generates public and private keys using elliptic curve cryptography so the secret key does not need to be shared over unsecured channels. The approach also allows direct encryption and decryption of characters from the full 128-character ASCII table using their numeric values, avoiding the need for a character mapping table. The advantages are seen as improved security, efficiency and faster computation compared to other techniques.
The document contains a series of questions and answers related to the topics of cryptography and network security. It is divided into 5 units, with questions ranging from defining basic terms to explaining concepts in more depth. Some of the questions ask for examples or demonstrations of algorithms and techniques. The document serves as a study guide or practice test for a course on cryptography and security.
The document contains a series of questions and answers related to the topics of cryptography and network security. It is divided into 5 units, with questions ranging from basic concepts and definitions to practical applications and algorithms. Some of the key topics covered include symmetric and asymmetric encryption, cryptanalysis techniques like brute force attacks, cryptographic hash functions, digital signatures, authentication protocols, and network security mechanisms like IPsec.
This document contains questions and answers related to the topics of cryptography and network security. It covers topics such as information security, data integrity, cryptanalysis, cryptographic algorithms, symmetric and asymmetric key cryptography, hashing, digital signatures, network attacks, and security protocols. The questions range from definitions of technical terms to short explanations of cryptographic concepts and mechanisms.
Lesson 04 - Symmetric and Asymmetric Key Encryptions (1).pptxMohamedNowfeek1
1. Symmetric key cryptography uses a single secret key for both encryption and decryption, while asymmetric key cryptography uses two different but mathematically related keys, a public key and a private key.
2. In asymmetric encryption, the public key is used to encrypt messages and its companion private key is used to decrypt messages. Only the recipient who possesses the private key can decrypt messages encrypted with their public key.
3. The essential steps of asymmetric encryption are that each user generates a public-private key pair, places their public key in a register for others, and encrypts messages sent to recipients with their public key which can only be decrypted with the corresponding private key.
This document discusses various aspects of network security, including:
1. Secure communication techniques like confidentiality, authentication, message integrity, and access control.
2. Encryption methods like symmetric encryption (DES, 3DES, AES), asymmetric encryption (RSA, Diffie-Hellman), and digital certificates.
3. Network security protocols like SSL/TLS, VPNs, and techniques for securing wireless networks like WEP.
This document discusses securely sharing data in multi-owner cloud environments for dynamic groups. It proposes a method for securely sharing data files with other users in a group on an untrusted cloud. The method supports dynamic groups where new users can access files uploaded before joining without contacting owners. User revocation is achieved through a revocation list without updating other users' secret keys. Encryption overhead is constant, independent of revoked users. The scheme provides secure access control and preserves user privacy by hiding identities from the cloud.
Generate an Encryption Key by using Biometric Cryptosystems to secure transfe...IOSR Journals
The document describes a proposed method for generating an encryption key from biometric cryptosystems to securely transfer data over a network. It involves extracting minutiae points from a fingerprint scan, generating a cryptographic key from the biometric template, and using an RSA encryption algorithm with the biometric-derived private key. A public key is also calculated based on ridge and furrow patterns in the fingerprint scan. The goal is to uniquely generate encryption keys for each individual using their biometric fingerprint information to add an extra layer of security beyond traditional encryption techniques.
This document proposes a new technique to solve the key exchange problem in cryptography. It discusses existing key exchange methods that rely on additional encryption processes or pre-shared secrets. The proposed method mixes the cipher key with the encrypted data block such that only the intended receiver can extract both the key and data. This allows key exchange without pre-sharing secrets or additional encryption steps. It aims to provide a more efficient and secure key exchange technique compared to traditional methods.
This document provides a technical review of secure banking using RSA and AES encryption methodologies. It discusses how RSA and AES are commonly used encryption standards for secure data transmission between ATMs and bank servers. The document first provides background on ATM security measures and risks of attacks. It then reviews related work analyzing encryption techniques. The document proposes using a one-time password in addition to a PIN for ATM authentication. It concludes that implementing encryption standards like RSA and AES can make transactions more secure and build trust in online banking.
This document analyzes the performance of various modulation schemes for achieving energy efficient communication over fading channels in wireless sensor networks. It finds that for long transmission distances, low-order modulations like BPSK are optimal due to their lower SNR requirements. However, as transmission distance decreases, higher-order modulations like 16-QAM and 64-QAM become more optimal since they can transmit more bits per symbol, outweighing their higher SNR needs. Simulations show lifetime extensions up to 550% are possible in short-range networks by using higher-order modulations instead of just BPSK. The optimal modulation depends on transmission distance and balancing the energy used by electronic components versus power amplifiers.
This document provides a review of mobility management techniques in vehicular ad hoc networks (VANETs). It discusses three modes of communication in VANETs: vehicle-to-infrastructure (V2I), vehicle-to-vehicle (V2V), and hybrid vehicle (HV) communication. For each communication mode, different mobility management schemes are required due to their unique characteristics. The document also discusses mobility management challenges in VANETs and outlines some open research issues in improving mobility management for seamless communication in these dynamic networks.
This document provides a review of different techniques for segmenting brain MRI images to detect tumors. It compares the K-means and Fuzzy C-means clustering algorithms. K-means is an exclusive clustering algorithm that groups data points into distinct clusters, while Fuzzy C-means is an overlapping clustering algorithm that allows data points to belong to multiple clusters. The document finds that Fuzzy C-means requires more time for brain tumor detection compared to other methods like hierarchical clustering or K-means. It also reviews related work applying these clustering algorithms to segment brain MRI images.
1) The document simulates and compares the performance of AODV and DSDV routing protocols in a mobile ad hoc network under three conditions: when users are fixed, when users move towards the base station, and when users move away from the base station.
2) The results show that both protocols have higher packet delivery and lower packet loss when users are either fixed or moving towards the base station, since signal strength is better in those scenarios. Performance degrades when users move away from the base station due to weaker signals.
3) AODV generally has better performance than DSDV, with higher throughput and packet delivery rates observed across the different user mobility conditions.
This document describes the design and implementation of 4-bit QPSK and 256-bit QAM modulation techniques using MATLAB. It compares the two techniques based on SNR, BER, and efficiency. The key steps of implementing each technique in MATLAB are outlined, including generating random bits, modulation, adding noise, and measuring BER. Simulation results show scatter plots and eye diagrams of the modulated signals. A table compares the results, showing that 256-bit QAM provides better performance than 4-bit QPSK. The document concludes that QAM modulation is more effective for digital transmission systems.
The document proposes a hybrid technique using Anisotropic Scale Invariant Feature Transform (A-SIFT) and Robust Ensemble Support Vector Machine (RESVM) to accurately identify faces in images. A-SIFT improves upon traditional SIFT by applying anisotropic scaling to extract richer directional keypoints. Keypoints are processed with RESVM and hypothesis testing to increase accuracy above 95% by repeatedly reprocessing images until the threshold is met. The technique was tested on similar and different facial images and achieved better results than SIFT in retrieval time and reduced keypoints.
This document studies the effects of dielectric superstrate thickness on microstrip patch antenna parameters. Three types of probes-fed patch antennas (rectangular, circular, and square) were designed to operate at 2.4 GHz using Arlondiclad 880 substrate. The antennas were tested with and without an Arlondiclad 880 superstrate of varying thicknesses. It was found that adding a superstrate slightly degraded performance by lowering the resonant frequency and increasing return loss and VSWR, while decreasing bandwidth and gain. Specifically, increasing the superstrate thickness or dielectric constant resulted in greater changes to the antenna parameters.
This document describes a wireless environment monitoring system that utilizes soil energy as a sustainable power source for wireless sensors. The system uses a microbial fuel cell to generate electricity from the microbial activity in soil. Two microbial fuel cells were created using different soil types and various additives to produce different current and voltage outputs. An electronic circuit was designed on a printed circuit board with components like a microcontroller and ZigBee transceiver. Sensors for temperature and humidity were connected to the circuit to monitor the environment wirelessly. The system provides a low-cost way to power remote sensors without needing battery replacement and avoids the high costs of wiring a power source.
1) The document proposes a model for a frequency tunable inverted-F antenna that uses ferrite material.
2) The resonant frequency of the antenna can be significantly shifted from 2.41GHz to 3.15GHz, a 31% shift, by increasing the static magnetic field placed on the ferrite material.
3) Altering the permeability of the ferrite allows tuning of the antenna's resonant frequency without changing the physical dimensions, providing flexibility to operate over a wide frequency range.
This document summarizes a research paper that presents a speech enhancement method using stationary wavelet transform. The method first classifies speech into voiced, unvoiced, and silence regions based on short-time energy. It then applies different thresholding techniques to the wavelet coefficients of each region - modified hard thresholding for voiced speech, semi-soft thresholding for unvoiced speech, and setting coefficients to zero for silence. Experimental results using speech from the TIMIT database corrupted with white Gaussian noise at various SNR levels show improved performance over other popular denoising methods.
This document reviews the design of an energy-optimized wireless sensor node that encrypts data for transmission. It discusses how sensing schemes that group nodes into clusters and transmit aggregated data can reduce energy consumption compared to individual node transmissions. The proposed node design calculates the minimum transmission power needed based on received signal strength and uses a periodic sleep/wake cycle to optimize energy when not sensing or transmitting. It aims to encrypt data at both the node and network level to further optimize energy usage for wireless communication.
This document discusses group consumption modes. It analyzes factors that impact group consumption, including external environmental factors like technological developments enabling new forms of online and offline interactions, as well as internal motivational factors at both the group and individual level. The document then proposes that group consumption modes can be divided into four types based on two dimensions: vertical (group relationship intensity) and horizontal (consumption action period). These four types are instrument-oriented, information-oriented, enjoyment-oriented, and relationship-oriented consumption modes. Finally, the document notes that consumption modes are dynamic and can evolve over time.
The document summarizes a study of different microstrip patch antenna configurations with slotted ground planes. Three antenna designs were proposed and their performance evaluated through simulation: a conventional square patch, an elliptical patch, and a star-shaped patch. All antennas were mounted on an FR4 substrate. The effects of adding different slot patterns to the ground plane on resonance frequency, bandwidth, gain and efficiency were analyzed parametrically. Key findings were that reshaping the patch and adding slots increased bandwidth and shifted resonance frequency. The elliptical and star patches in particular performed better than the conventional design. Three antenna configurations were selected for fabrication and measurement based on the simulations: a conventional patch with a slot under the patch, an elliptical patch with slots
1) The document describes a study conducted to improve call drop rates in a GSM network through RF optimization.
2) Drive testing was performed before and after optimization using TEMS software to record network parameters like RxLevel, RxQuality, and events.
3) Analysis found call drops were occurring due to issues like handover failures between sectors, interference from adjacent channels, and overshooting due to antenna tilt.
4) Corrective actions taken included defining neighbors between sectors, adjusting frequencies to reduce interference, and lowering the mechanical tilt of an antenna.
5) Post-optimization drive testing showed improvements in RxLevel, RxQuality, and a reduction in dropped calls.
This document describes the design of an intelligent autonomous wheeled robot that uses RF transmission for communication. The robot has two modes - automatic mode where it can make its own decisions, and user control mode where a user can control it remotely. It is designed using a microcontroller and can perform tasks like object recognition using computer vision and color detection in MATLAB, as well as wall painting using pneumatic systems. The robot's movement is controlled by DC motors and it uses sensors like ultrasonic sensors and gas sensors to navigate autonomously. RF transmission allows communication between the robot and a remote control unit. The overall aim is to develop a low-cost robotic system for industrial applications like material handling.
This document reviews cryptography techniques to secure the Ad-hoc On-Demand Distance Vector (AODV) routing protocol in mobile ad-hoc networks. It discusses various types of attacks on AODV like impersonation, denial of service, eavesdropping, black hole attacks, wormhole attacks, and Sybil attacks. It then proposes using the RC6 cryptography algorithm to secure AODV by encrypting data packets and detecting and removing malicious nodes launching black hole attacks. Simulation results show that after applying RC6, the packet delivery ratio and throughput of AODV increase while delay decreases, improving the security and performance of the network under attack.
The document describes a proposed modification to the conventional Booth multiplier that aims to increase its speed by applying concepts from Vedic mathematics. Specifically, it utilizes the Urdhva Tiryakbhyam formula to generate all partial products concurrently rather than sequentially. The proposed 8x8 bit multiplier was coded in VHDL, simulated, and found to have a path delay 44.35% lower than a conventional Booth multiplier, demonstrating its potential for higher speed.
This document discusses image deblurring techniques. It begins by introducing image restoration and focusing on image deblurring. It then discusses challenges with image deblurring being an ill-posed problem. It reviews existing approaches to screen image deconvolution including estimating point spread functions and iteratively estimating blur kernels and sharp images. The document also discusses handling spatially variant blur and summarizes the relationship between the proposed method and previous work for different blur types. It proposes using color filters in the aperture to exploit parallax cues for segmentation and blur estimation. Finally, it proposes moving the image sensor circularly during exposure to prevent high frequency attenuation from motion blur.
This document describes modeling an adaptive controller for an aircraft roll control system using PID, fuzzy-PID, and genetic algorithm. It begins by introducing the aircraft roll control system and motivation for developing an adaptive controller to minimize errors from noisy analog sensor signals. It then provides the mathematical model of aircraft roll dynamics and describes modeling the real-time flight control system in MATLAB/Simulink. The document evaluates PID, fuzzy-PID, and PID-GA (genetic algorithm) controllers for aircraft roll control and finds that the PID-GA controller delivers the best performance.
Digital Twins Computer Networking Paper Presentation.pptxaryanpankaj78
A Digital Twin in computer networking is a virtual representation of a physical network, used to simulate, analyze, and optimize network performance and reliability. It leverages real-time data to enhance network management, predict issues, and improve decision-making processes.
Discover the latest insights on Data Driven Maintenance with our comprehensive webinar presentation. Learn about traditional maintenance challenges, the right approach to utilizing data, and the benefits of adopting a Data Driven Maintenance strategy. Explore real-world examples, industry best practices, and innovative solutions like FMECA and the D3M model. This presentation, led by expert Jules Oudmans, is essential for asset owners looking to optimize their maintenance processes and leverage digital technologies for improved efficiency and performance. Download now to stay ahead in the evolving maintenance landscape.
Applications of artificial Intelligence in Mechanical Engineering.pdfAtif Razi
Historically, mechanical engineering has relied heavily on human expertise and empirical methods to solve complex problems. With the introduction of computer-aided design (CAD) and finite element analysis (FEA), the field took its first steps towards digitization. These tools allowed engineers to simulate and analyze mechanical systems with greater accuracy and efficiency. However, the sheer volume of data generated by modern engineering systems and the increasing complexity of these systems have necessitated more advanced analytical tools, paving the way for AI.
AI offers the capability to process vast amounts of data, identify patterns, and make predictions with a level of speed and accuracy unattainable by traditional methods. This has profound implications for mechanical engineering, enabling more efficient design processes, predictive maintenance strategies, and optimized manufacturing operations. AI-driven tools can learn from historical data, adapt to new information, and continuously improve their performance, making them invaluable in tackling the multifaceted challenges of modern mechanical engineering.
Null Bangalore | Pentesters Approach to AWS IAMDivyanshu
#Abstract:
- Learn more about the real-world methods for auditing AWS IAM (Identity and Access Management) as a pentester. So let us proceed with a brief discussion of IAM as well as some typical misconfigurations and their potential exploits in order to reinforce the understanding of IAM security best practices.
- Gain actionable insights into AWS IAM policies and roles, using hands on approach.
#Prerequisites:
- Basic understanding of AWS services and architecture
- Familiarity with cloud security concepts
- Experience using the AWS Management Console or AWS CLI.
- For hands on lab create account on [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
# Scenario Covered:
- Basics of IAM in AWS
- Implementing IAM Policies with Least Privilege to Manage S3 Bucket
- Objective: Create an S3 bucket with least privilege IAM policy and validate access.
- Steps:
- Create S3 bucket.
- Attach least privilege policy to IAM user.
- Validate access.
- Exploiting IAM PassRole Misconfiguration
-Allows a user to pass a specific IAM role to an AWS service (ec2), typically used for service access delegation. Then exploit PassRole Misconfiguration granting unauthorized access to sensitive resources.
- Objective: Demonstrate how a PassRole misconfiguration can grant unauthorized access.
- Steps:
- Allow user to pass IAM role to EC2.
- Exploit misconfiguration for unauthorized access.
- Access sensitive resources.
- Exploiting IAM AssumeRole Misconfiguration with Overly Permissive Role
- An overly permissive IAM role configuration can lead to privilege escalation by creating a role with administrative privileges and allow a user to assume this role.
- Objective: Show how overly permissive IAM roles can lead to privilege escalation.
- Steps:
- Create role with administrative privileges.
- Allow user to assume the role.
- Perform administrative actions.
- Differentiation between PassRole vs AssumeRole
Try at [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
Software Engineering and Project Management - Software Testing + Agile Method...Prakhyath Rai
Software Testing: A Strategic Approach to Software Testing, Strategic Issues, Test Strategies for Conventional Software, Test Strategies for Object -Oriented Software, Validation Testing, System Testing, The Art of Debugging.
Agile Methodology: Before Agile – Waterfall, Agile Development.
Home security is of paramount importance in today's world, where we rely more on technology, home
security is crucial. Using technology to make homes safer and easier to control from anywhere is
important. Home security is important for the occupant’s safety. In this paper, we came up with a low cost,
AI based model home security system. The system has a user-friendly interface, allowing users to start
model training and face detection with simple keyboard commands. Our goal is to introduce an innovative
home security system using facial recognition technology. Unlike traditional systems, this system trains
and saves images of friends and family members. The system scans this folder to recognize familiar faces
and provides real-time monitoring. If an unfamiliar face is detected, it promptly sends an email alert,
ensuring a proactive response to potential security threats.
Use PyCharm for remote debugging of WSL on a Windo cf5c162d672e4e58b4dde5d797...shadow0702a
This document serves as a comprehensive step-by-step guide on how to effectively use PyCharm for remote debugging of the Windows Subsystem for Linux (WSL) on a local Windows machine. It meticulously outlines several critical steps in the process, starting with the crucial task of enabling permissions, followed by the installation and configuration of WSL.
The guide then proceeds to explain how to set up the SSH service within the WSL environment, an integral part of the process. Alongside this, it also provides detailed instructions on how to modify the inbound rules of the Windows firewall to facilitate the process, ensuring that there are no connectivity issues that could potentially hinder the debugging process.
The document further emphasizes on the importance of checking the connection between the Windows and WSL environments, providing instructions on how to ensure that the connection is optimal and ready for remote debugging.
It also offers an in-depth guide on how to configure the WSL interpreter and files within the PyCharm environment. This is essential for ensuring that the debugging process is set up correctly and that the program can be run effectively within the WSL terminal.
Additionally, the document provides guidance on how to set up breakpoints for debugging, a fundamental aspect of the debugging process which allows the developer to stop the execution of their code at certain points and inspect their program at those stages.
Finally, the document concludes by providing a link to a reference blog. This blog offers additional information and guidance on configuring the remote Python interpreter in PyCharm, providing the reader with a well-rounded understanding of the process.
Use PyCharm for remote debugging of WSL on a Windo cf5c162d672e4e58b4dde5d797...
Deniable Encryption Key
1. IOSR Journal of Computer Engineering (IOSR-JCE)
e-ISSN: 2278-0661, p- ISSN: 2278-8727Volume 11, Issue 4 (May. - Jun. 2013), PP 08-12
www.iosrjournals.org
www.iosrjournals.org 8 | Page
Deniable Encryption Key
P.Lokesh Kumar Reddy11
, B.Rama Bhupal Reddy2
, S.Rama Krishna3
1
Rama Raja Institute of Technology and Science, Tirupati, A.P., India
2
Dept. of Mathematics, K.S.R.M. College of Engineering, Kadapa, A.P., India
3
Dept. of Computer Science, S.V. University, Tirupati, A.P., India
Abstract: Deniable encryption is an important that allows a user (a sender and/or a receiver) to escape a
coercion attempted by a coercive adversary. Such an adversary approaches the coerced user after transmission
forcing him to reveal all his random inputs used during encryption or decryption. Since traditional encryption
schemes commit the user to his random inputs, the user is forced to reveal the true values of all his random
inputs (including the encrypted/decrypted messages and the encryption/decryption keys) which are
verifiable by this coercer using the intercepted cipher text. In this scenario, a coercer may force the user to
perform actions against his wish. An appealing property in the mediated RSA, PKI was introduced that, the
user has no information, neither about his full private (decryption) key, nor the factorization of the RSA
public modulus, which represents an excellent step toward achieving in forcibility in public key encryption,
since, a coercer cannot ask the user to reveal such unknown information. In this pa- per we present a scheme
for receiver-deniable public-key encryption, by which, the receiver is able to lie about the decrypted message to
a coercer and hence, escape a coercion. On one hand, the receiver is able to decrypt for the correct
message, on the other hand, all the information held by the receiver, when opened to a coercer, do not
allow this coercer to verify the encrypted message and consequently, approaching this user becomes useless
from the very beginning.
Keywords: Deniable encryption, mediated PKI, oblivious transfer, public-key encryption, RSA
I. Introduction
While traditional encryption schemes protect the privacy of the sender and the receiver against
eavesdroppers (semantic security), they fail to provide protection against coercers. A coercive adversary
has the power to approach the user (the sender and/or the receiver) after the ciphertext is transmitted and of
course recorded by this adversary. It commands the user to reveal all his random inputs used during
encryption or decryption. Since the cipher text produced, using standard encryption schemes (specially, public-
key encryption) commits the user to his random inputs, It cannot lie about the true plaintext. Such
commitments allow the coercive adversary to verify the validity of the opened message. Deniable encryption
allows a user to escape coercion. Namely, if this user opens all his inputs (including the claimed encrypted
message) to a coercer, the coercer fails to prove the validity or invalidity of the opened message.
Deniable encryption maybe classified according to which party is coerced: sender-deniable
encryption schemes are resilient against coercing the sender. The Definitions for receiver-deniable and sender-
receiver- deniable follow analogously. When the sender and the receiver initially share a common secret key,
this is spoken off as shared-key deniable encryption. In deniable public- key encryption, no pre-shared
information and no communications are assumed prior to the encryption process. This follows from the
assumptions of standard public-key encryption schemes. Yet, deniable public-key encryption is more
challenging than deniable shared-key encryption since the public key of the receiver is already known to
everyone including the coercer, consequently, neither the sender nor the receiver can lie about the receiver’s
public key.
The work in [5] showed that it is possible by simple tricks to transform any sender-deniable
encryption scheme to a receiver-deniable encryption scheme and vice- versa. Also, they showed that, with
the help of other parties with at least one of them remains un-attacked, it is possible to transform a sender-
deniable encryption scheme to a sender-receiver-deniable encryption scheme.
In our recent work of, we devised a sender-deniable public-key encryption based on quadratic
residuosity of a composite modulus and showed how to device a sender- deniable public-key encryption from
any trapdoor per mutation. However, when the schemes are transformed to be receiver-deniable using the
tricks of [5], the schemes are no more one-move schemes. Considering only one- move schemes, receiver
deniability is more challenging than sender-deniability since in the later case, everyone knows the public-key
of the receiver but the private key of the receiver is known only to the receiver who is beyond the reach of the
coercer. In the former case, the receiver maybe coerced to reveal his private key which is verifiable using the
public key and a dummy message.
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Deniable encryption is very useful in the protocols where coercive adversaries come to play as
a potential threat. For example, deniable encryption protects voters from being coerced during electronic
elections [6, 9]. It is also very useful to protect bidders in electronic auctions. Generally, deniable encryption is
very important when a party is forced to act against his/her wish.
Our construction assumes the existence of the simple and efficient mediated-RSA (mRSA) [2] as
the PKI in place. mRSA was invented as a method to achieve fast revocation in RSA PKI. mRSA involves a
special entity, called the SEM (SEcurity Mediator), an on-line partially trusted server, to help signing or
decrypting messages. The CA generates the private key d corresponding to Bob’s (the receiver’s) public
key e and splits this private key into two pieces. One piece (dSEM) is delivered to the SEM and the other
piece (dBob) is delivered to Bob. The pair (e, N) is the usual RSA public key. An important property to notice
here is that Bob himself has no information neither about his full private key, nor about the factorization
of the public modulus N . This property is an excellent step toward achieving deniability since, a coercer will
not ask Bob to reveal such unknown information. To decrypt a received cipher text, C, each party (Bob
and SEM) performs his/her partial decryption on C; finally the partial decryptions are combined to recover the
plaintext message M. To revoke Bob ability to sign or de- crypt messages, the CA instructs the SEM to stop
issuing partial decryptions or signatures (spoken of as tokens) for Bob public key. At this instant, Bob’s
signature and/or decryption capabilities are revoked. The functionality is equivalent to (and indistinguishable
from) standard RSA due to the fact that the splitting of the private key is transparent to the outside, i.e.,
to those who use the corresponding public key. Also, knowledge of a half-key cannot be used to derive the
entire private key. Therefore, neither Bob nor the SEM can decrypt or sign a message without mutual consent.
As our PKI is established, we turn to discuss our tools. To complete the deniability service, we need an
efficient protocol for (1-out-of-n) oblivious transfer (OT1). Rabin proposed the concept of oblivious transfer
(OT) in the cryptographic scenario. In this case the sender has only one secret bit b and would like to
have the receiver to get it with probability ½, on the other hand, the receiver does not want the sender to
know whether it gets b or not. For OT1 , the sender has two secrets b1 and b2 , the receiver will get
one of them at the receiver’s choice.
The receiver does not want the sender to know which bit he chooses and the receiver must not
know any information other than he chosen. Oblivious transfer is a fundamental primitive in many
cryptographic applications and secure distributed computations and has many applications such as private
information retrieval (PIR), fair electronic contract signing, oblivious secure computation, etc. Our proposed
receiver-deniable public-key encryption scheme requires one invocation of OT1 between Bob and the SEM.
Also we need a Secured mechanism [10] to make the OT protocol deniable.
The rest of the paper is organized as follows: Section 2 describes the related work. Section 3
gives our motivations and contributions. The underlying PKI and the oblivious transfer protocol are
described in Section 4.
Section 5 states our assumptions and model. . The strong version is given in Section 6. Section 7
shows the techniques to transform deniability. The bandwidth is improved in Section 8. Finally, the
conclusions are given in Section 9.
II. Related Work
The work in [5] constructed a sender-deniable public- key encryption scheme based on trapdoor
permutations. However, the scheme falls short of achieving an appropriate level of deniability, that is, to
achieve a high deniability, the size of the cipher text corresponding to a one bit encryption is super-polynomial
and hence inefficient. In the deniable public-key encryption scheme of [5], a one bit plaintext requires tn
bits of cipher text where t is the bit-length of elements in a translucent set St and t = s + k for security
parameters n, s and k.
The scheme provides deniability of 4/n and decryption error of n2−k . Hence, to achieve a high level
of deniability and a sufficiently low decryption error, the cipher text is super- polynomial and almost
impractical [5]. Constructed two deniable public-key encryption schemes based on translucent sets, the first
represents the building block for the second which they have called, the “Parity Scheme”. The work in [5] also
notified that in order to build a one-round scheme, different approaches are required. Also, [5] introduced
techniques for the less challenging, deniable shared- key encryption and showed that the one-time-pad is a
perfect deniable shared-key encryption.
Based on the sender-deniable public-key encryption, the work in [4] described a general
multiparty computations allowing a set of players to compute a common function of their inputs with the
ability to escape a coercion. In fact, deniable encryption has an impact on designing adaptively secure
multiparty computations [4] since, the notion of deniability is stronger than the notion of non-committing
encryption Schemes.
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III. Motivations and Contributions
In this Section we describe our motivations and contributions of the work in this paper.
3.1 Motivations
Deniable public-key encryption is a strong primitive, essential in all cryptographic protocols where a
coercive adversary comes to play with high potential. Deniable public-key encryption realizes the “Receipt-
freeness” attribute which is a very important attribute in electronic voting, electronic bidding and auctions. The
schemes proposed in [5] fall short of achieving the desired level of deniability and correctness unless the
size of the cipher text corresponding to a one bit encryption is super- polynomial. An appealing property in
the mRSA PKI [2] is that the user himself has no information neither about his full private key, nor about
the factorization of the public modulus N , consequently, a coercer will not ask the user for such unknown
information.
3.2 Contributions
The contributions of this paper are to introduce an efficient receiver-deniable public-key encryption
(RD-PKE) scheme. Our proposed scheme enjoys the following properties:
• It is a one-move scheme without any pre-encryption information required to be sent between the sender and the
receiver prior to encryption.
• No pre-shared secret information is required between the sender and the receiver.
• Achieves a high level of deniability equivalent to the factorization of a large two-prime modulus.
• No deciphering errors.
• The bandwidth (cipher text bit-length) is significantly improved compared to previous constructions.
Efficiency, We reduce the required bandwidth (cipher- text bit-length) to, 2 lg N bits for a single bit
encryption, where N is a two-prime RSA modulus. Moreover, this bandwidth can be efficiently improved,
that is, 2 lg N bits of cipher text allow about lg N − δ bits of plaintext encryption where δ is a short
randomizing string. At the same time, our scheme provides strong deniability (i.e. undetectable cheating)
equivalent to the infeasibility to factor a sufficiently large two-prime modulus. Unlike the schemes of [5],
our scheme produces no decryption errors and hence, more reliable. We introduce two versions of our RD-
PKE scheme, a weak version to declare our idea and security proofs, and then we show a simple modification to
improve this weak version to be a strong RD-PKE scheme.
IV. Preliminaries
4.1 Mediated RSA
Mediated RSA was invented as a simple method to achieve fast revocation in public-key
cryptosystem. As usual, a trusted certificate authority (CA) sets up the RSA modulus N , the public
exponent e and the private exponent d for the user. Next, instead of delivering d to the user, the CA splits d
into two pieces dSEM and duser such that d = dSEM + duser modϕ(N ) where ϕ(N ) is the RSA Euler totient.
Finally, the CA secretly delivers duser to the user and dSEM to the SEM.
Encryption, For Alice to encrypt a message M ZN to Bob, she uses Bob’s public pair (N, e) to compute
the usual RSA cipher text C = M e
mod N and sends C to Bob.
Decryption, on the reception of C by Bob, the decryption process is as follows:
• Bob delivers C to the SEM.
• If Bob’s key is revoked, the SEM returns ERROR and aborts, else,
• The SEM computes her partial decryption P DSEM = C dSEM modN and returns P DSEM to
Bob.• Bob computes his partial decryption P DBob = C dBob
Mod N and extracts M = P DSEM P DBob mod N.
It is important to notice that the SEM gains no information about the decrypted message M [2].
4.2. Oblivious Transfer
Our proposed RD-PKE requires that Bob involves with the SEM in an OT1 invocation to get his
encrypted bit. The main objective of the oblivious transfer protocols was to improve the efficiency and security
of the protocols. The protocols of [18] have several appealing properties.
First, they prove efficiency over previous protocols, second, there are no number theoretic constrains
on the strings to be obliviously transferred, third, the protocols have bandwidth-computation tradeoffs which
make them suitable for variety of applications. The protocols of operate over a group Zq of prime order, more
precisely, Gq is a subgroup of order q of Z* where p is prime and q/p - 1. Let g be a generator group and assume
that the Diffie-Hellman assumption holds. In their OT1: The sender owns two strings r0 and r1. He chooses a
random element U Zq and publishes it. The chooser picks a random 1 ≤ k ≤ q and sets pkσ = gk where {0,
1} is the chooser’s choice.
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The chooser also computes pk1−σ = U/pkσ and sends pk0 to the sender. The sender picks a random
R and computes gR and U R, he also computes pkR
and pkR
= U R
/pkR
. The sender computes pk1−σ = U/pkσ
and sends pk0 to the sender. The sender picks a random R and computes gR and U R, he also computes pkR
and pkR = UR
/pkR
. The sender The chooser selects a random k and sets pkσ = gk where σ {0, ..., n − 1}
is his choice, it holds that pki
= Ui
/pk0
i = (1, ..., n − 1). The chooser sends pk0 to the sender. The sender
computes pkR as well as pkR
V. Assumptions and Model
We define a receiver-deniable public-key encryption (RD- PKE) scheme as a scheme by which, the
receiver is able to lie about the decrypted message to a coercer and hence, escape coercion. On one hand, the
receiver is able to decrypt for the correct message, on the other hand, all the information held (or extractable)
by the receiver when opened to a coercer, do not allow this coercer to verify the encrypted message and
consequently, approaching the receiver becomes useless from the very beginning.
The participants in our scheme are the certificate authority (CA), the security mediator (SEM), the
sender (Alice), the receiver (Bob) and the coercive adversary (coercer). As usual, the CA is assumed to be fully
trusted by all participants. The SEM is a semi-trusted party in the sense that it follows the execution steps
word for word but it is willing to learn any information that could be leaked during execution. Alice is
assumed to be beyond the reach of any coercer while Bob is possibly coerced.
The coercer has the power to approach Bob coercing him to reveal the decrypted message, the
decryption partial key and all the parameters he used during decryption.
This paper describes the scheme allowing one bit encryption at a time. The reader will notice that the
scheme can be easily adapted to allow multiple bits encryption at a time. We assume that an mRSA PKI
is already in place. Hence, the pair (e, N ) represents Bob’s public key while dBob (respectively dSEM )
are the pieces of Bob’s private key d held by Bob (respectively the SEM). Let bt be the true bit to be
encrypted by Alice to Bob. The scheme is described next.
Encryption. To encrypt the bit bt to Bob, Alice proceeds as follows:
• Picks a lg N bits string R R ZN. Let r0 ...rn−1 be the binary representation of R.
• Scans the binary representation of R for an index (Pointer) i such that ri = bt
• Computes and sends the two encryptions, Ci = i
mod N and CR = Re
mod N to Bob.
VI. Full Deniability
In this Section we show how to achieve full deniability in our RD-PKE scheme, i.e., the scheme
will be deniable even if the coercer is capable of eavesdropping the Alice-Bob channel and the SEM-Bob
channel as well. The problem is that the OT protocol is not deniable and hence commits Bob to what he
receives from the SEM. We benefit from the fact that the SEM and all its users are in the same domain (or
System) this fact facilitates the sharing of a time-synchronous pseudo-random string between the SEM server
and each user in its domain. Typical example is the OTPs (one time passwords) achieved via secure ID tokens
(e.g. The well known and widely used tamper- resistance RSA-Secured tokens [10]). The SEM and the user in
the SEM’s domain share a pseudo-random string which is updated every 30 (or 60) seconds at both parties. It
is important to notice that this pseudo-random string is synchronously shared based on internal clocks
implemented at both parties, consequently, the update is performed offline without any communication,
hence this pseudo-random string cannot be reached via eaves- dropping. Let X (τ ) be the pseudo-random
string shared between Bob and the SEM at any given time interval,
VII. Deniability Transformation
O ur proposed scheme cannot withstand coercion of the sender, since a coerced sender is forced to
reveal R and the index i which are verifiable by the coercer using the receiver’s public key. A sender-
deniable encryption is easily transformed to a receiver-deniable encryption and vice-versa. A sender-receiver
deniable scheme requires n intermediaries, I1, ..., In , with at least one of them remains honest (un attacked).
The sender chooses n bits b1, ..., bn such that L bi = bt and sends bi to each Ii using the sender deniable public-
key encryption
VIII. Bandwidth Improvement
It is possible to further improve the bandwidth of our receiver-deniable public-key encryption
scheme as follows: Let M= {M0 , ..., Mm−1} be the set of all possible strings According to the plaintext message,
Alice sets the indices
I= iv−1 , ..., i0 where ij points to Mij in R. In this case, each index ij is of ` bits where ` < lg lg
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N − lg `. The maximum number of indices per encryption (i.e. Contained in CI ) is vmax ' lg N/`. Since each
index points to a string of ` bits, then, the encryption pair (CI, CR) encrypts about ` lg N/` = lg N bits of plaintext.
Hence, for a 1024 bits RSA modulus, a 2048 bits of cipher text encrypts 1024 − δ bits of plaintext where δ is
the bit-length of r.
Finally, for each index, ij , Bob involves with the SEM in one invocation of OT1 oblivious transfer
of strings to get Mij .
IX. Results and Discussion
We proposed a scheme for receiver-deniable public-key encryption. Our scheme is based on mediated
RSA PKI. Our scheme proves efficiency over that proposed in [5] in the sense of bandwidth, deniability and
decipherability. The scheme can be transformed to a sender-deniable or a sender-receiver-deniable using the
tricks of [5]. The complexity of the oblivious transfer protocol used in our RD-PKE was studied and improved
in [11]. The reader may have noticed that, our proposed scheme is not restricted to RSA. Our scheme could be
applied to any PKI with the mediated property. A final thing worth noting is that when our receiver-deniable
scheme is transformed to a sender-deniable one, it is no more a one-move scheme. To construct a one-move
sender-deniable scheme, other approaches must be invented. For example, one may consider the sender-
deniable scheme in [12].
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