Cryptography and Symmetric Key Algorithms
Cryptography is the study of secure communications techniques that allow only the sender and intended recipient of a message to view its contents.
OR
The art of creating and implementing secret codes and ciphers is known as cryptography.
This document summarizes the history and evolution of information security from its origins during World War II to the present day. It describes how computer security began with early mainframes and military applications, then expanded to include networking and the internet. Key developments included the ARPANET, identification of security issues in the 1970s/80s, growth of hacking conferences in the 1990s, and increased threats of cyber attacks in modern times. The document also defines core information security concepts.
Chapter 5 Planning for Security-students.pptShruthi48
Management plays a key role in developing information security policies, standards, and practices that form the foundation of an organization's security program. These include enterprise policies that set strategic direction, issue-specific policies that address technology areas, and system-specific policies that provide technical guidance. Policies must be properly disseminated, understood, agreed to, and uniformly enforced. They also require ongoing management through regular reviews and updates to remain effective as an organization's needs change over time.
Social and Professional Issues in Computing - EthicsDyuti Islam
This document discusses professional ethics in computing. It defines professional ethics as codes of conduct that govern how members of a profession interact with each other and third parties. It then explains why professional codes of ethics are important, such as symbolizing professionalism and protecting interests. The document outlines the key principles of the Joint IEEE-CS/ACM Code of Ethics, including public interest, clients/employers, products, judgment, and lifelong learning. It concludes by noting limitations of codes, such as not covering every case, and the need for personal ethics aligned with professional codes.
This document is from a textbook on database systems. It introduces fundamental concepts such as what a database is, the role of database management systems, and typical database functionality including defining schemas, loading data, querying, and concurrency control. It also discusses different types of database users and the advantages of the database approach such as data sharing and integrity enforcement. Examples of entity-relationship diagrams and database relations are provided to illustrate conceptual data modeling.
Internet Message Access Protocol (IMAP) is a communications protocol for email retrieval and storage developed by Mark Crispin in 1986 at Stanford University as an alternative to POP.
IMAP uses port 143, and IMAP over SSL (IMAPS) uses port 993. IMAP, unlike POP, specifically allows multiple clients simultaneously connected to the same mailbox, and through flags stored on the server, different clients accessing the same mailbox at the same or different times can detect state changes made by other clients.
This document provides an introduction to encryption. It defines encryption as the process of converting data into an unrecognizable form. Encryption is important for achieving data security and privacy. It allows users to securely protect passwords, personal data, and ensure files have not been altered. Examples of encryption applications include web browsing, email, and hard drive encryption. The document then describes how encryption works by encrypting a message using an encryption key. It also outlines different encryption methods like hashing, symmetric, and asymmetric encryption.
This document discusses different types of firewalls and how they work. It begins by explaining that firewalls come in many shapes and sizes, and sometimes a firewall is a collection of computers. All communication must pass through the firewall. It then discusses packet filters, stateful packet inspection engines, application gateways, and circuit-level gateways. Packet filters use transport layer information like IP addresses and port numbers to filter traffic. Stateful packet filters track client-server sessions to match return packets. Application gateways run proxy programs that filter traffic at the application layer. Circuit-level gateways filter traffic at the circuit level. A combination of these is known as a dynamic packet filter. The document also discusses additional firewall functions like network address
This document summarizes the history and evolution of information security from its origins during World War II to the present day. It describes how computer security began with early mainframes and military applications, then expanded to include networking and the internet. Key developments included the ARPANET, identification of security issues in the 1970s/80s, growth of hacking conferences in the 1990s, and increased threats of cyber attacks in modern times. The document also defines core information security concepts.
Chapter 5 Planning for Security-students.pptShruthi48
Management plays a key role in developing information security policies, standards, and practices that form the foundation of an organization's security program. These include enterprise policies that set strategic direction, issue-specific policies that address technology areas, and system-specific policies that provide technical guidance. Policies must be properly disseminated, understood, agreed to, and uniformly enforced. They also require ongoing management through regular reviews and updates to remain effective as an organization's needs change over time.
Social and Professional Issues in Computing - EthicsDyuti Islam
This document discusses professional ethics in computing. It defines professional ethics as codes of conduct that govern how members of a profession interact with each other and third parties. It then explains why professional codes of ethics are important, such as symbolizing professionalism and protecting interests. The document outlines the key principles of the Joint IEEE-CS/ACM Code of Ethics, including public interest, clients/employers, products, judgment, and lifelong learning. It concludes by noting limitations of codes, such as not covering every case, and the need for personal ethics aligned with professional codes.
This document is from a textbook on database systems. It introduces fundamental concepts such as what a database is, the role of database management systems, and typical database functionality including defining schemas, loading data, querying, and concurrency control. It also discusses different types of database users and the advantages of the database approach such as data sharing and integrity enforcement. Examples of entity-relationship diagrams and database relations are provided to illustrate conceptual data modeling.
Internet Message Access Protocol (IMAP) is a communications protocol for email retrieval and storage developed by Mark Crispin in 1986 at Stanford University as an alternative to POP.
IMAP uses port 143, and IMAP over SSL (IMAPS) uses port 993. IMAP, unlike POP, specifically allows multiple clients simultaneously connected to the same mailbox, and through flags stored on the server, different clients accessing the same mailbox at the same or different times can detect state changes made by other clients.
This document provides an introduction to encryption. It defines encryption as the process of converting data into an unrecognizable form. Encryption is important for achieving data security and privacy. It allows users to securely protect passwords, personal data, and ensure files have not been altered. Examples of encryption applications include web browsing, email, and hard drive encryption. The document then describes how encryption works by encrypting a message using an encryption key. It also outlines different encryption methods like hashing, symmetric, and asymmetric encryption.
This document discusses different types of firewalls and how they work. It begins by explaining that firewalls come in many shapes and sizes, and sometimes a firewall is a collection of computers. All communication must pass through the firewall. It then discusses packet filters, stateful packet inspection engines, application gateways, and circuit-level gateways. Packet filters use transport layer information like IP addresses and port numbers to filter traffic. Stateful packet filters track client-server sessions to match return packets. Application gateways run proxy programs that filter traffic at the application layer. Circuit-level gateways filter traffic at the circuit level. A combination of these is known as a dynamic packet filter. The document also discusses additional firewall functions like network address
Cryptography and network security Nit701Amit Pathak
Cryptography and network security descries the security parameter with the help of public and private key. Digital signature is one of the most important area which we apply in our daily life for transferring the data.
This document discusses email security and ways to secure emails. It covers confidentiality, integrity and availability as important aspects of email security. Some key points:
- Email security deals with unauthorized access and inspection of emails during transmission and storage. Emails pass through untrusted servers making them vulnerable.
- Methods to secure emails include using encryption tools like PGP and S/MIME at the sender and receiver sides, and during transmission.
- PGP provides encryption, authentication, compression and ensures email compatibility. It is free, worldwide and based on secure algorithms. S/MIME allows secure exchange of emails with attachments and is supported by major email clients.
Web spoofing involves masquerading as another user or program to gain an illegitimate advantage. There are several types of spoofing, including IP spoofing where the sender address is falsified, and web spoofing where an adversary can observe and modify web pages sent to the victim. Defenses include ingress/egress filtering to block spoofed IP addresses, and users verifying URLs and SSL certificates when entering sensitive information online.
Database security aims to protect data from unauthorized access through various security controls. This includes restricting access (secrecy), ensuring data integrity, and maintaining data availability. Common threats include accidental issues like hardware/software errors and natural disasters, as well as deliberate actions by authorized or unauthorized users. Microsoft Access provides security features like user accounts, permissions, and database passwords to control access and protect data.
This document provides an overview of cryptography. It defines cryptography as the study of secret writing and the principles and methods of transforming intelligible messages into unintelligible messages. It then defines key terms like plaintext, ciphertext, cipher, key, encipherment, decipherment, cryptanalysis, and code. The document discusses the process of encryption and decryption using a secret key. It also provides brief histories of ancient ciphers like those used by Julius Caesar and describes some early methods from the 1200s. The document concludes with discussions of security services, attacks, security mechanisms, and digital signatures.
Data encryption in database management systemRabin BK
The document discusses data encryption in databases. It defines encryption as a process that transforms data into cipher text that can only be read by those with the decryption key. There are different levels of encryption, including transparent encryption of the entire database, column-level encryption of individual columns, and field-level encryption of specific data fields. Advantages of encryption include security of data at all times, maintaining data integrity and privacy, and protecting data across devices. Disadvantages include key management issues and potential performance impacts of encrypting database content.
This document discusses security technologies taught in an Illinois Institute of Technology course. It covers firewalls, intrusion detection systems, dial-up protection, and other topics. The learning objectives are to define types of firewalls, discuss firewall implementation approaches, and understand technologies like encryption and biometrics. Firewalls examined include packet filtering, proxy, stateful inspection, dynamic, and kernel proxy firewalls. Intrusion detection systems can be host-based or network-based, using signatures or anomalies. Remote authentication and terminal access control systems help secure dial-up access.
Chapter 11 laws and ethic information securitySyaiful Ahdan
This document provides an overview of key concepts regarding law and ethics in information security. It discusses the differences between laws and ethics, and how policies function similarly to laws within an organization. Several major US laws are outlined, including those covering general computer crimes, privacy, identity theft, export and espionage, copyright, and financial reporting. International agreements and professional organizations relevant to information security ethics are also mentioned. The document aims to help readers understand the legal and ethical responsibilities for information security practitioners.
This document discusses cryptography and its role in information security. It describes different types of security attacks like interception, modification, and fabrication. It also summarizes common security services like confidentiality, authentication, integrity, and different encryption techniques like symmetric key cryptography, public key cryptography, Caesar cipher and RSA algorithm. The document concludes with explanations of firewalls and their technical working as a security measure to monitor and control access between networks.
This document discusses internet anonymity and covers different types of anonymity systems like proxy servers, remailers, mix networks, onion routing, and I2P. It provides an overview of I2P, explaining that it is an anonymous network that routes traffic through other peers in an encrypted manner to anonymize users. The conclusion emphasizes that anonymity networks like Tor and I2P cannot solve all anonymity problems and that users still need to be smart to protect their anonymity when using these systems.
The document discusses security policies and standards. It defines different types of policies like enterprise, issue-specific, and systems-specific policies. It also discusses how policies are developed based on an organization's mission and vision. Effective policies require dissemination, review, comprehension, and compliance. Frameworks and industry standards also guide policy development. Additionally, the document outlines the importance of security education, training, and awareness programs to inform employees and reinforce security practices.
The document discusses email security threats and protocols. It describes how emails are vulnerable targets for hackers due to their widespread use and standardized protocols. Common attacks involve delivering malware or disclosing sensitive information by intercepting emails. The Pretty Good Privacy (PGP) and Secure/Multipurpose Internet Mail Extensions (S/MIME) protocols provide encryption, authentication, and integrity to secure emails. PGP uses public/private key pairs and symmetric encryption to encrypt messages and verify identities. S/MIME also uses digital signatures and encryption to securely encode email contents and attachments.
This document discusses basic security concepts, including definitions of security, assets, and the principle of easiest penetration. It describes three classifications of protection: prevention, detection, and reaction. Examples are given for physical and cyber security. The goals of security are defined as integrity, confidentiality, and availability. Common security threats are interruption, interception, modification, and fabrication. Vulnerabilities in computing systems can occur in data, software, hardware, and exposed assets. Methods of defense include encryption, software/hardware controls, policies, and physical controls. System access control and data access control are important methods for making systems secure using identification, authentication, and access authorization.
The document discusses various methods for securing client devices and applications. It describes securing the client by using hardware system security, securing the operating system software, and protecting peripheral devices. Specific techniques discussed include secure booting using UEFI and secure boot standards, establishing a hardware root of trust, preventing electromagnetic spying, and addressing risks from supply chain infections. The document also covers securing the operating system through configuration, patch management, and using antimalware software like antivirus, antispam, and antispyware programs.
Electronic mail security requires confidentiality, authentication, integrity, and non-repudiation. Privacy Enhanced Mail (PEM) and Pretty Good Privacy (PGP) provide these security services for email. PEM uses canonical conversion, digital signatures, encryption, and base64 encoding. PGP provides authentication via digital signatures and confidentiality through symmetric encryption of messages with randomly generated session keys. Secure/Multipurpose Internet Mail Extensions (S/MIME) also supports signed and encrypted email to provide security.
This document discusses information security and system security. It defines information, information security, and the goals of security including confidentiality, integrity and availability. It describes different types of attacks such as interruption, interception, modification and fabrication. It explains passive attacks like eavesdropping and traffic analysis, as well as active attacks including masquerade, replay, message modification, and denial of service. The document outlines why computer security is needed and covers topics like vulnerabilities, threats, and controls to protect against various security risks.
This document discusses sensitive data and how to protect it. It begins by defining sensitive data as information that must be safeguarded against unwanted disclosure due to legal, privacy or proprietary reasons. It then lists examples of sensitive data and outlines three key aspects to measuring data sensitivity: confidentiality, integrity and availability. Next, it describes the types of sensitive data hackers may target from organizations. Finally, it recommends three steps to protect sensitive data: identify all sensitive data, promptly respond to and assess risks, and monitor and implement adequate security measures. The conclusion emphasizes the importance of protecting sensitive data to build strong business relationships and trust.
This chapter discusses ethics for IT professionals and users. It outlines the relationships IT professionals must manage, such as with employers, clients, suppliers and other professionals. Each relationship has potential ethical issues. Professional codes of ethics provide guidance, while certification and licensing affect ethical behavior. For IT users, the chapter discusses common ethical issues and how policies can support ethical practices by defining appropriate usage.
The document discusses active and passive network attacks. An active attack intercepts network connections to alter message content, potentially changing system resources, while a passive attack observes and copies messages without altering them, so the victim is not notified. Common active and passive attacks are man-in-the-middle attacks and packet sniffing, respectively. The document also provides tips for preventing security attacks like keeping software updated and using firewalls and strong passwords.
This document provides an introduction and table of contents to cryptography. It discusses the main goals of cryptography which are confidentiality, data integrity, authentication, and non-repudiation. It then defines key vocabulary terms used in cryptography such as plaintext, ciphertext, encryption, decryption, stream ciphers, block ciphers, and cryptosystems. Finally, it provides a brief high-level history of cryptography mentioning examples from 400 BC Spartan sky tale cipher to Julius Caesar's substitution cipher.
Cryptography and network security Nit701Amit Pathak
Cryptography and network security descries the security parameter with the help of public and private key. Digital signature is one of the most important area which we apply in our daily life for transferring the data.
This document discusses email security and ways to secure emails. It covers confidentiality, integrity and availability as important aspects of email security. Some key points:
- Email security deals with unauthorized access and inspection of emails during transmission and storage. Emails pass through untrusted servers making them vulnerable.
- Methods to secure emails include using encryption tools like PGP and S/MIME at the sender and receiver sides, and during transmission.
- PGP provides encryption, authentication, compression and ensures email compatibility. It is free, worldwide and based on secure algorithms. S/MIME allows secure exchange of emails with attachments and is supported by major email clients.
Web spoofing involves masquerading as another user or program to gain an illegitimate advantage. There are several types of spoofing, including IP spoofing where the sender address is falsified, and web spoofing where an adversary can observe and modify web pages sent to the victim. Defenses include ingress/egress filtering to block spoofed IP addresses, and users verifying URLs and SSL certificates when entering sensitive information online.
Database security aims to protect data from unauthorized access through various security controls. This includes restricting access (secrecy), ensuring data integrity, and maintaining data availability. Common threats include accidental issues like hardware/software errors and natural disasters, as well as deliberate actions by authorized or unauthorized users. Microsoft Access provides security features like user accounts, permissions, and database passwords to control access and protect data.
This document provides an overview of cryptography. It defines cryptography as the study of secret writing and the principles and methods of transforming intelligible messages into unintelligible messages. It then defines key terms like plaintext, ciphertext, cipher, key, encipherment, decipherment, cryptanalysis, and code. The document discusses the process of encryption and decryption using a secret key. It also provides brief histories of ancient ciphers like those used by Julius Caesar and describes some early methods from the 1200s. The document concludes with discussions of security services, attacks, security mechanisms, and digital signatures.
Data encryption in database management systemRabin BK
The document discusses data encryption in databases. It defines encryption as a process that transforms data into cipher text that can only be read by those with the decryption key. There are different levels of encryption, including transparent encryption of the entire database, column-level encryption of individual columns, and field-level encryption of specific data fields. Advantages of encryption include security of data at all times, maintaining data integrity and privacy, and protecting data across devices. Disadvantages include key management issues and potential performance impacts of encrypting database content.
This document discusses security technologies taught in an Illinois Institute of Technology course. It covers firewalls, intrusion detection systems, dial-up protection, and other topics. The learning objectives are to define types of firewalls, discuss firewall implementation approaches, and understand technologies like encryption and biometrics. Firewalls examined include packet filtering, proxy, stateful inspection, dynamic, and kernel proxy firewalls. Intrusion detection systems can be host-based or network-based, using signatures or anomalies. Remote authentication and terminal access control systems help secure dial-up access.
Chapter 11 laws and ethic information securitySyaiful Ahdan
This document provides an overview of key concepts regarding law and ethics in information security. It discusses the differences between laws and ethics, and how policies function similarly to laws within an organization. Several major US laws are outlined, including those covering general computer crimes, privacy, identity theft, export and espionage, copyright, and financial reporting. International agreements and professional organizations relevant to information security ethics are also mentioned. The document aims to help readers understand the legal and ethical responsibilities for information security practitioners.
This document discusses cryptography and its role in information security. It describes different types of security attacks like interception, modification, and fabrication. It also summarizes common security services like confidentiality, authentication, integrity, and different encryption techniques like symmetric key cryptography, public key cryptography, Caesar cipher and RSA algorithm. The document concludes with explanations of firewalls and their technical working as a security measure to monitor and control access between networks.
This document discusses internet anonymity and covers different types of anonymity systems like proxy servers, remailers, mix networks, onion routing, and I2P. It provides an overview of I2P, explaining that it is an anonymous network that routes traffic through other peers in an encrypted manner to anonymize users. The conclusion emphasizes that anonymity networks like Tor and I2P cannot solve all anonymity problems and that users still need to be smart to protect their anonymity when using these systems.
The document discusses security policies and standards. It defines different types of policies like enterprise, issue-specific, and systems-specific policies. It also discusses how policies are developed based on an organization's mission and vision. Effective policies require dissemination, review, comprehension, and compliance. Frameworks and industry standards also guide policy development. Additionally, the document outlines the importance of security education, training, and awareness programs to inform employees and reinforce security practices.
The document discusses email security threats and protocols. It describes how emails are vulnerable targets for hackers due to their widespread use and standardized protocols. Common attacks involve delivering malware or disclosing sensitive information by intercepting emails. The Pretty Good Privacy (PGP) and Secure/Multipurpose Internet Mail Extensions (S/MIME) protocols provide encryption, authentication, and integrity to secure emails. PGP uses public/private key pairs and symmetric encryption to encrypt messages and verify identities. S/MIME also uses digital signatures and encryption to securely encode email contents and attachments.
This document discusses basic security concepts, including definitions of security, assets, and the principle of easiest penetration. It describes three classifications of protection: prevention, detection, and reaction. Examples are given for physical and cyber security. The goals of security are defined as integrity, confidentiality, and availability. Common security threats are interruption, interception, modification, and fabrication. Vulnerabilities in computing systems can occur in data, software, hardware, and exposed assets. Methods of defense include encryption, software/hardware controls, policies, and physical controls. System access control and data access control are important methods for making systems secure using identification, authentication, and access authorization.
The document discusses various methods for securing client devices and applications. It describes securing the client by using hardware system security, securing the operating system software, and protecting peripheral devices. Specific techniques discussed include secure booting using UEFI and secure boot standards, establishing a hardware root of trust, preventing electromagnetic spying, and addressing risks from supply chain infections. The document also covers securing the operating system through configuration, patch management, and using antimalware software like antivirus, antispam, and antispyware programs.
Electronic mail security requires confidentiality, authentication, integrity, and non-repudiation. Privacy Enhanced Mail (PEM) and Pretty Good Privacy (PGP) provide these security services for email. PEM uses canonical conversion, digital signatures, encryption, and base64 encoding. PGP provides authentication via digital signatures and confidentiality through symmetric encryption of messages with randomly generated session keys. Secure/Multipurpose Internet Mail Extensions (S/MIME) also supports signed and encrypted email to provide security.
This document discusses information security and system security. It defines information, information security, and the goals of security including confidentiality, integrity and availability. It describes different types of attacks such as interruption, interception, modification and fabrication. It explains passive attacks like eavesdropping and traffic analysis, as well as active attacks including masquerade, replay, message modification, and denial of service. The document outlines why computer security is needed and covers topics like vulnerabilities, threats, and controls to protect against various security risks.
This document discusses sensitive data and how to protect it. It begins by defining sensitive data as information that must be safeguarded against unwanted disclosure due to legal, privacy or proprietary reasons. It then lists examples of sensitive data and outlines three key aspects to measuring data sensitivity: confidentiality, integrity and availability. Next, it describes the types of sensitive data hackers may target from organizations. Finally, it recommends three steps to protect sensitive data: identify all sensitive data, promptly respond to and assess risks, and monitor and implement adequate security measures. The conclusion emphasizes the importance of protecting sensitive data to build strong business relationships and trust.
This chapter discusses ethics for IT professionals and users. It outlines the relationships IT professionals must manage, such as with employers, clients, suppliers and other professionals. Each relationship has potential ethical issues. Professional codes of ethics provide guidance, while certification and licensing affect ethical behavior. For IT users, the chapter discusses common ethical issues and how policies can support ethical practices by defining appropriate usage.
The document discusses active and passive network attacks. An active attack intercepts network connections to alter message content, potentially changing system resources, while a passive attack observes and copies messages without altering them, so the victim is not notified. Common active and passive attacks are man-in-the-middle attacks and packet sniffing, respectively. The document also provides tips for preventing security attacks like keeping software updated and using firewalls and strong passwords.
This document provides an introduction and table of contents to cryptography. It discusses the main goals of cryptography which are confidentiality, data integrity, authentication, and non-repudiation. It then defines key vocabulary terms used in cryptography such as plaintext, ciphertext, encryption, decryption, stream ciphers, block ciphers, and cryptosystems. Finally, it provides a brief high-level history of cryptography mentioning examples from 400 BC Spartan sky tale cipher to Julius Caesar's substitution cipher.
The chapters follow a sequence that I consider to be a logical
progression through the subject matter, and in the main, follow
the order of objectives stated in the BTEC unit of Electrical and
Electronic Principles. The major exception to this is that the topics of
instrumentation and measurements do not appear in a specifi c chapter
of that title. Instead, the various instruments and measurement methods
are integrated within those chapters where the relevant theory is
covered.
Occasionally a word or phrase will appear in bold blue type, and close
by will be a box with a blue background. These emphasised words or
phrases may be ones that are not familiar to students, and within the
box will be an explanation of the words used in the text.
Throughout the book, Worked Examples appear as Q questions
in bold type, followed by A answers. In all chapters, Assignment
Questions are provided for students to solve.
The fi rst chapter deals with the basic concepts of electricity; the use of
standard form and its adaptation to scientifi c notation; SI and derived
units; and the plotting of graphs. This chapter is intended to provide
a means of ensuring that all students on a given course start with the
same background knowledge. Also included in this chapter are notes
regarding communication. In particular, emphasis is placed on logical
and thorough presentation of information, etc. in the solution of
Assignment Questions and Practical Assignment reports.
This Textbook supersedes the second edition of Fundamental
Electrical and Electronic Principles. In response to comments
from colleges requesting that the contents more closely match the
objectives of the BTEC unit Electrical and Electronic Principles,
some chapters have been removed and some exchanged with the
companion book Further Electrical and Electronic Principles, ISBN
9780750687478. Also, in order to encourage students to use other
reference sources, those chapters that have been totally removed
may be accessed on the website address http://books.elsevier.
com/companions/9780750687379. The previous edition included
Supplementary Worked Examples at the end of each chapter. The
majority of these have now been included within each chapter as
Worked Examples, and those that have been removed may be accessed
on the above website.
This book continues with the philosophy of the previous editions
in that it may be used as a complete set of course notes for students
undertaking the study of Electrical and Electronic Principles in the
fi rst year of a BTEC National Diploma/Certifi cate course. It also
provides coverage for some other courses, including foundation/
bridging courses which require the study of Electrical and Electronic
Engineering.
Fundamental Electrical and Electronic Principles contains 349
illustrations, 112 worked examples, 26 suggested practical assignments
and 234 assignment questions. The answers to the latter are to be found
towards the end of
This document discusses computer security and network cryptography. It begins by explaining how organizations can use cryptosystems like symmetric and asymmetric encryption to protect data. Symmetric encryption is faster but requires secure key exchange, while asymmetric encryption uses public and private key pairs. The document then defines cryptography terminology and components like plaintext, ciphertext, encryption, decryption, and cryptanalysis. It describes techniques like substitution and transposition ciphers. The rest of the document discusses encryption models, algorithms, and cryptanalysis methods like ciphertext-only and known-plaintext attacks.
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.
Sri Hari Uppalapati gave a presentation on the One Time Pad (OTP) encryption method. OTP uses a randomly generated key that is as long as the plaintext message. The key is used to encrypt the message one time and then discarded, making it impossible to decrypt the ciphertext without the key. OTP is information theoretically secure if implemented correctly, but it is not practical for most uses due to the key management issues. The presentation received average to good peer reviews, with comments noting the clear explanations but room for improvement. Reviewers suggested providing more examples or comparisons to other methods.
Cryptography is the practice of hiding information to store or communicate it in a secure way. It allows for confidentiality, integrity, and authentication of messages. There are two main types: symmetric key cryptography which uses a single key for encryption and decryption, and asymmetric key cryptography which uses different public and private keys. Popular symmetric algorithms include AES and DES, while RSA is an example of an asymmetric algorithm. The seminar discussed the components, processes, and applications of cryptography as well as examples of algorithms and common attacks.
I presented this overview lecture at Computer Applications for the 21st century – Synergies and Vistas organized by Vidyasagar College, Kolkata in 2008
Topics listed below are explained in the PPT:
Introduction
CIA Triad
Mechanisms of Cryptography
OSI Security Architecture
Security Attacks
Security Mechanisms
Security Services
Cryptography vs Steganography
Network Security Model
Cryptographic techniques
Stream Cipher vs Block cipher
The key to information security is protecting information and information systems from unauthorized access through various means. Some common methods of securing information include encryption, authentication, passwords, digital signatures, and controlling access. Public key encryption uses a private and public key system where the private key is known only to the user and the public key can be shared more widely. Encryption scrambles data using an algorithm and key to make it unreadable without the proper key.
Bt0088 cryptography and network security1Techglyphs
The document discusses various topics related to cryptography and network security including:
1. The need for network security to prevent damage to organizations from hostile software or intruders.
2. Security attacks are any actions that compromise information security, while vulnerabilities are weaknesses that can be exploited by threats to cause harm.
3. The difference between substitution and transposition techniques for encryption, where substitution exchanges letters and transposition rearranges them.
4. Caesar cipher encryption of a sample plaintext using a key of 3.
This document contains a question bank with answers related to cyber security. It discusses topics like the CIA triad of confidentiality, integrity and availability, authentication and authorization. It also defines terms like availability, integrity, non-repudiation and confidentiality. Examples are provided for different authentication factors like something you know, something you have and something you are. The document also discusses symmetric and asymmetric encryption, firewalls and the fundamentals of the domain name system.
BEGINS FROM SCRATCH TO FUTURE METHODS OF CRYPTOGRAPHY. PROVIDES A DEEP INSIGHT INTO HISTORY,USES,APPLICATION,DIFFERENT TYPES AND METHODS OF CRYPTOGRAPHY. THANK YOU
A Novel Key Distribution Scheme f or a Visual Crypto SystemIRJET Journal
This document proposes a novel key distribution scheme for visual cryptography. It begins with an introduction to cryptography and visual cryptography. It then describes the existing Diffie-Hellman key exchange algorithm. The proposed method generates a shared secret key through a multi-step process using asymmetric key cryptography and modulus operation on private keys and a public image. Both parties are able to derive the same symmetric key for encrypting future communications without directly transmitting their private keys. The methodology and implementation details are provided, along with experimental results demonstrating the generation of matching keys within 0.11 seconds on average.
Blind Signature Scheme Based On Elliptical Curve Cryptography (ECC)IOSR Journals
This document summarizes a blind signature scheme based on elliptic curve cryptography. It begins with an introduction to cryptography and the history of cryptography. It then discusses symmetric key cryptography, asymmetric key cryptography including public and private key pairs. It describes digital signatures, how they are generated and verified. It introduces the concept of blind signatures, how a message can be signed without revealing its contents to the signer. It discusses the mathematics behind elliptic curves including elliptic curve equations and algorithms for performing group operations on elliptic curves. It provides details on representing divisor classes using Mumford representation and using Cantor's algorithm to compute the sum of two divisor classes.
Blind Signature Scheme Based On Elliptical Curve Cryptography (ECC)IOSR Journals
This document summarizes a blind signature scheme based on elliptic curve cryptography. It begins with an introduction to cryptography and the history of cryptography. It then discusses symmetric key cryptography, asymmetric key cryptography including public and private key pairs. It describes digital signatures, how they are generated and verified. It introduces the concept of blind signatures, how a message can be signed without revealing its contents to the signer. It discusses the mathematics behind elliptic curves and elliptic curve cryptography. It describes how to represent points on an elliptic curve and perform operations like point addition. The document focuses on implementing a blind digital signature scheme using elliptic curve cryptography.
This document summarizes a blind signature scheme based on elliptic curve cryptography. It begins with an introduction to cryptography and the history of cryptography. It then discusses symmetric key cryptography, asymmetric key cryptography including public and private key pairs. It describes digital signatures, how they are generated and verified. It introduces the concept of blind signatures, how a message can be signed without revealing its contents to the signer. It discusses the mathematics behind elliptic curves including elliptic curve equations and algorithms for performing group operations on elliptic curves. It provides details on representing divisor classes using Mumford representation and using Cantor's algorithm to compute the sum of two divisor classes.
This document provides an overview of cryptography techniques. It discusses symmetric and asymmetric encryption algorithms such as AES, DES, RSA. It also describes classic encryption techniques like the Caesar cipher, rail fence cipher and the one-time pad (Vernam cipher). The document proposes a modified encryption technique that combines two of these methods (e.g. Caesar cipher and rail fence cipher) to encrypt a message, requiring the receiver to use the same two methods in the same order to decrypt it correctly. This is intended to increase security by confusing attackers about the exact encryption method used.
The document discusses cryptography and the RSA encryption algorithm. It begins with an introduction to cryptography and its uses. It then covers the history of cryptography, common security issues, and different cryptographic techniques like symmetric and asymmetric encryption. The document focuses on explaining the RSA algorithm, how it works using public and private keys, and why factoring large numbers makes RSA secure. It provides an overview of the key aspects of cryptography and the RSA algorithm.
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What will you get from this session?
1. Insights into integrating generative AI.
2. Understanding how this integration enhances test automation within the UiPath platform
3. Practical demonstrations
4. Exploration of real-world use cases illustrating the benefits of AI-driven test automation for UiPath
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What is generative AI
Test Automation with generative AI and Open AI.
UiPath integration with generative AI
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CI/CD with in UiPath
End-to-end overview of CI/CD pipeline with Azure devops
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Discover how MongoDB Atlas and vector search technology can revolutionize your application's search capabilities. This comprehensive presentation covers:
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Partecipate alla presentazione per immergervi in una storia di interoperabilità, standard e formati aperti, per poi discutere del ruolo importante che i contributori hanno in una comunità open source sostenibile.
BIO: Sostenitrice del software libero e dei formati standard e aperti. È stata un membro attivo dei progetti Fedora e openSUSE e ha co-fondato l'Associazione LibreItalia dove è stata coinvolta in diversi eventi, migrazioni e formazione relativi a LibreOffice. In precedenza ha lavorato a migrazioni e corsi di formazione su LibreOffice per diverse amministrazioni pubbliche e privati. Da gennaio 2020 lavora in SUSE come Software Release Engineer per Uyuni e SUSE Manager e quando non segue la sua passione per i computer e per Geeko coltiva la sua curiosità per l'astronomia (da cui deriva il suo nickname deneb_alpha).
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
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The discussion will extend to how AI can be used to transform XML content. In particular, the focus will be on the use of AI XPath extension functions in XSLT, Schematron, Schematron Quick Fixes, or for XML content refactoring.
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2. Cryptography
Cryptography is the study of secure communications
techniques that allow only the sender and intended
recipient of a message to view its contents.
OR
The art of creating and implementing secret codes and
ciphers is known as cryptography.
3. Historical Milestones in Cryptography
As long as mankind has been communicating, we’ve
used secretive means to hide the true meaning of
those communications from the uninitiated.
o Ancient societies used a complex system of secret
symbols to represent safe places to stay during
times of war.
o Modern civilizations use a variety of codes and
ciphers to facilitate private communication between
individuals and groups.
4. Caesar Cipher
One of the earliest known cipher systems was used by
Julius Caesar to communicate with Cicero in Rome while
he was conquering Europe. Caesar knew that there were
several risks when sending messages.
For that reason, Caesar developed a cryptographic system
now known as the Caesar cipher.
To encrypt a message, you simply shift each letter of the
alphabet three places to the right. For example, A would
become D, and B would become E. If you reach the end
of the alphabet during this process, you simply wrap
around to the beginning so that X becomes A, Y becomes
B, and Z becomes C.
For this reason, the Caesar cipher also became known as
the ROT3 and C3 cipher.
5. Caesar Cipher
Here’s an example of the Caesar cipher in action. The
first line contains the original sentence, and the
second line shows what the sentence looks like when
it is encrypted using the Caesar cipher:
Original: THE DIE HAS BEEN CAST
Encrypted: WKH GLH KDV EHHQ FDVW
To decrypt the message, you simply shift each letter
three places to the left.
6. Goals of Cryptography
Security practitioners use cryptographic systems to
meet four fundamental goals:
Confidentiality
Integrity
Authentication
nonrepudiation
7. Confidentiality
Confidentiality ensures that data remains private while at rest,
such as when stored on a disk, or in transit, such as during
transmission between two or more parties.
Data at rest, or stored data, is that which resides in a permanent
location awaiting access. Examples of data at rest include data
stored on hard drives, backup tapes, cloud storage services, USB
devices, and other storage media.
Data in motion, or data “on the wire,” is data being transmitted
across a network between two systems. Data in motion might be
traveling on a corporate network, a wireless network, or the public
Internet.
Both data in motion and data at rest pose different types of
confidentiality risks that cryptography can protect against. For
example, data in motion may be susceptible to eavesdropping
attacks, whereas data at rest is more susceptible to the theft of
physical devices.
8. Integrity
Integrity ensures that data is not altered without
authorization.
Message integrity is enforced through the use of
encrypted message digests, known as digital
signatures created upon transmission of a message.
The recipient of the message simply verifies that the
message’s digital signature is valid, ensuring that the
message was not altered in transit. Integrity can be
enforced by both public and secret key cryptosystems.
9. Authentication
Authentication verifies the claimed identity of system users and
is a major function of cryptosystems. For example, suppose that
Bob wants to establish a communications session with Alice and
they are both participants in a shared secret communications
system. Alice might use a challenge-response authentication
technique to ensure that Bob is who he claims to be.
10. Nonrepudiation
Nonrepudiation provides assurance to the recipient
that the message was originated by the sender and
not someone masquerading as the sender.
For example,
If Jim and Bob participate in a secret key
communication system, they can both produce the
same encrypted message using their shared secret
key. Nonrepudiation is offered only by public key, or
asymmetric, cryptosystems.
11. Cryptography Concepts
As with any science, you must be familiar with certain
terminology before studying cryptography. Let’s take a look
at a few of the key terms used to describe codes and
ciphers.
Before a message is put into a coded form, it is known as
a plaintext message and is represented by the letter P
when encryption functions are described.
The sender of a message uses a cryptographic algorithm
to encrypt the plaintext message and produce a
ciphertext message, represented by the letter C.
This message is transmitted by some physical or
electronic means to the recipient. The recipient then uses
a predetermined algorithm to decrypt the ciphertext
message and retrieve the plaintext version.
12. Cryptography Concepts: Keys
All cryptographic algorithms rely on keys to maintain
their security.
For the most part, a key is nothing more than a
number.
It’s usually a very large binary number, but a number
nonetheless.
Every algorithm has a specific key space. The key
space is the range of values that are valid for use as
a key for a specific algorithm.
A key space is defined by its bit size.
13. Cryptography Concepts: The Kerchoff
Principle
All cryptography relies on algorithms. An algorithm is
a set of rules, usually mathematical, that dictates how
enciphering and deciphering processes are to take
place.
Most cryptographers follow the Kerchoff principle, a
concept that makes algorithms known and public,
allowing anyone to examine and test them.
The Kerchoff principle is a cryptographic system
should be secure even if everything about the system,
except the key, is public knowledge. The principle can
be summed up as “The enemy knows the system.”
14. Cryptographic Mathematics
To fully understand cryptography, you must first
understand the basics of binary mathematics
and the logical operations used to manipulate
binary values.
15. Boolean Mathematics
Boolean mathematics defines the rules used for the
bits and bytes that form the nervous system of any
computer.
The computer’s reliance upon the Boolean system has
electrical origins. In an electrical circuit, there are only
two possible states—on (representing the presence of
electrical current) and off (representing the absence of
electrical current).
In general, computer scientists refer to the on
condition as a true value and the off condition as a
false value.
16. Logical Operations
The Boolean mathematics of cryptography
uses a variety of logical functions to
manipulate data. We’ll take a brief look at
several of these operations
17. AND
The AND operation (represented by the ∧ symbol)
checks to see whether two values are both true.
18. OR
The OR operation (represented by the ∨ symbol)
checks to see whether at least one of the input values
is true.
19. NOT
The NOT operation (represented by the ∼ or ! symbol)
simply reverses the value of an input variable.
20. Exclusive OR
XOR function is commonly represented by the ⊕
symbol. The XOR function returns a true value when
only one of the input values is true. If both values are
false or both values are true, the output of the XOR
function is false.
21. Modulo Function
The modulo function is, quite simply, the remainder
value left over after a division operation is performed.
The modulo function is usually represented in
equations by the abbreviation mod, although it’s also
sometimes represented by the % operator.
22. One-Way Functions
A one-way function is a mathematical operation that
easily produces output values for each possible
combination of inputs but makes it impossible to
retrieve the input values.
Here’s an example,
Imagine you have a function that multiplies three
numbers together. If you restrict the input values to
single-digit numbers, it’s a relatively
straightforward matter to reverse-engineer this
function and determine the possible input values
by looking at the numerical output. For example,
the output value 15 was created by using the input
values 1, 3, and 5.
23. One-Way Functions
However, suppose you restrict the input values to five-
digit prime numbers. It’s still quite simple to obtain an
output value by using a computer or a good calculator,
but reverse-engineering is not quite so simple.
Can you figure out what three prime numbers were
used to obtain the output value 10,718,488,075,259?
Not so simple, eh? (As it turns out, the number is the
product of the prime numbers 17,093; 22,441; and
27,943.)
There are actually 8,363 five-digit prime numbers, so
this problem might be attacked using a computer and
a brute-force algorithm, but there’s no easy way to
figure it out in your head, that’s for sure!
24. Nonce
Cryptography often gains strength by adding
randomness to the encryption process. One method
by which this is accomplished is through the use of a
nonce.
“A nonce is a random number that acts as a
placeholder variable in mathematical functions.”
When the function is executed, the nonce is replaced
with a random number generated at the moment of
processing for one-time use. The nonce must be a
unique number each time it is used.
25. Zero-Knowledge Proof
One of the benefits of cryptography is found in the
mechanism to prove your knowledge of a fact to a third
party without revealing the fact itself to that third party. This
is often done with passwords and other secret
authenticators.
The classic example of a zero-knowledge proof involves
two individuals:
Peggy and Victor
Peggy knows the password to a secret door located inside
a circular cave.
Victor would like to buy the password from Peggy, but he
wants Peggy to prove that she knows the password before
paying her for it.
Peggy doesn’t want to tell Victor the password for fear that
he won’t pay later. The zero-knowledge proof can solve
their dilemma.
26. Zero-Knowledge Proof
Victor can stand at the entrance to the cave and watch Peggy
depart down the path. Peggy then reaches the door and opens it
using the password. She then passes through the door and
returns via path 2. Victor saw her leave down path 1 and return
via path 2, proving that she must know the correct password to
open the door.
27. Split Knowledge
When the information or privilege required to perform an
operation is divided among multiple users, no single person
has sufficient privileges to compromise the security of an
environment. This separation of duties and two-person control
contained in a single solution is called split knowledge.
The best example of split knowledge is seen in the concept of
key escrow. Using key escrow, cryptographic keys, digital
signatures, and even digital certificates can be stored or
backed up in a special database called the key escrow
database. In the event a user loses or damages their key, that
key can be extracted from the backup. However, if only a
single key escrow recovery agent exists, there is opportunity
for fraud and abuse of this privilege.
28. Split Knowledge
M of N Control requires that a minimum number of
agents (M) out of the total number of agents (N) work
together to perform high-security tasks. So,
implementing three of eight controls would require
three people out of the eight with the assigned work
task of key escrow recovery agent to work together to
pull a single key out of the key escrow database.
29. Work Function
You can measure the strength of a cryptography
system by measuring the effort in terms of cost and/or
time using a work function or work factor. Usually the
time and effort required to perform a complete brute-
force attack against an encryption system is what the
work function represents. The security and protection
offered by a cryptosystem is directly proportional to the
value of the work function/factor.
31. Codes vs. Ciphers
People often use the words code and cipher
interchangeably, but technically, they aren’t
interchangeable. There are important distinctions between
the two concepts.
Codes, which are cryptographic systems of symbols that
represent words or phrases, are sometimes secret, but
they are not necessarily meant to provide confidentiality. A
common example of a code is the “10 system” of
communications used by law enforcement agencies. Under
this system, the sentence “I received your communication
and understand the contents” is represented by the code
phrase “10-4.” This code is commonly known by the public,
but it does provide for ease of communication.
Some codes are secret. They may convey confidential
information using a secret codebook where the meaning of
the code is known only to the sender and recipient.
32. Codes vs. Ciphers
Ciphers, on the other hand, are always meant to hide
the true meaning of a message. They use a variety of
techniques to alter and rearrange the characters or
bits of a message to achieve confidentiality. Ciphers
convert messages from plain text to ciphertext on a bit
basis, character basis ,or block basis.
33. Transposition Ciphers
Transposition ciphers use an encryption algorithm to
rearrange the letters of a plaintext message, forming
the ciphertext message. The decryption algorithm
simply reverses the encryption transformation to
retrieve the original message.
34. Transposition Ciphers: Example
We’re attempting to encrypt the message “The fighters will
strike the enemy bases at noon” using the secret key
attacker.
First step:
Take the letters of the keyword and number them in alphabetical
order. The first appearance of the letter A receives the value 1;
the second appearance is numbered 2. The next letter in
sequence, C, is numbered 3, and so on. This results in the
following sequence:
35. Transposition Ciphers: Example
Second step:
The letters of the message are written in order underneath the
letters of the keyword:
Third step:
Sender enciphers the message by reading down each column;
the order in which the columns are read corresponds to the
numbers assigned in the first step. This produces the following
ciphertext:
37. Substitution Ciphers
You can express the ROT3 cipher in mathematical
terms by converting each letter to its decimal
equivalent (where A is 0 and Z is 25). You can then
add three to each plaintext letter to determine the
ciphertext. You account for the wrap-around by using
the modulo function discussed in the section
“Cryptographic Mathematics.”
The final encryption function for the Caesar cipher is
then this:
C = (P + 3) mod 26
The corresponding decryption function is as follows:
P = (C - 3) mod 26
38. Substitution Ciphers
Polyalphabetic substitution ciphers use multiple
alphabets in the same message to hinder decryption
efforts.
One of the most notable examples of a polyalphabetic
substitution cipher system is the Vigenère cipher.
40. Substitution Ciphers: Vigenère cipher
Notice that the chart is simply the alphabet written
repeatedly (26 times) under the master heading, shifting by
one letter each time. You need a key to use the Vigenère
system.
For example, the key could be secret. Then, you would
perform the following encryption process:
Write out the plain text.
Underneath, write out the encryption key, repeating the
key as many times as needed to establish a line of text
that is the same length as the plain text.
Convert each letter position from plain text to ciphertext.
Repeat steps 1 through 3 for each letter in the plaintext
version.
41. Convert each letter position from plain text to
ciphertext.
Locate the column headed by the first plaintext
character (a).
Next, locate the row headed by the first character of
the key (s).
Finally, locate where these two items intersect, and
write down the letter that appears there (s).
This is the ciphertext for that letter position.
42. One-Time Pads
A one-time pad is an extremely powerful type of
substitution cipher. One-time pads use a different
substitution alphabet for each letter of the plaintext
message.
They can be represented by the following encryption
function, where K is the encryption key used to encrypt
the plaintext letter P into the ciphertext letter
C: C = (P + K) mod 26
43. ???....
You may be thinking at this point that the Caesar
cipher, Vigenère cipher, and onetime pad sound very
similar. They are! The only difference is the key length.
The Caesar shift cipher uses a key of length one, the
Vigenère cipher uses a longer key (usually a word or
sentence), and the one-time pad uses a key that is as
long as the message itself.
44. Running Key Ciphers
Many cryptographic vulnerabilities surround the limited
length of the cryptographic key. As you learned in the
previous section, one-time pads avoid these
vulnerabilities by using a key that is at least as long as
the message. However, one-time pads are awkward to
implement because they require the physical
exchange of pads.
One common solution to this dilemma is the use of a
running key cipher (also known as a book cipher). In
this cipher, the encryption key is as long as the
message itself and is often chosen from a common
book.
45. Running Key Ciphers
Let’s look at an example.
Suppose you wanted to encrypt the message “Richard will
deliver the secret package to Matthew at the bus station
tomorrow” using the key just described. This message is 66
characters in length, so you’d use the first 66 characters of
the running key: “With much interest I sat watching him.
Savage though he was, and hideously marred.” Any
algorithm could then be used to encrypt the plaintext
message using this key. Let’s look at the example of
modulo 26 addition, which converts each letter to a decimal
equivalent, adds the plain text to the key, and then
performs a modulo 26 operation to yield the ciphertext. If
you assign the letter A the value 0 and the letter Z the value
25, you have the following encryption operation for the first
two words of the ciphertext:
46. Running Key Ciphers
When the recipient receives the ciphertext, they use the
same key and then subtract the key from the ciphertext,
perform a modulo 26 operation, and then convert the
resulting plain text back to alphabetic characters.
47. Block Ciphers
Block ciphers operate on “chunks,” or blocks, of a
message and apply the encryption algorithm to an
entire message block at the same time. The
transposition ciphers are examples of block ciphers.
The simple algorithm used in the challenge-response
algorithm takes an entire word and reverses its letters.
The more complicated columnar transposition cipher
works on an entire message (or a piece of a message)
and encrypts it using the transposition algorithm and a
secret keyword. Most modern encryption algorithms
implement some type of block cipher.
48. Stream Ciphers
Stream ciphers operate on one character or bit of a
message (or data stream) at a time. The Caesar cipher
is an example of a stream cipher. The one-time pad is
also a stream cipher because the algorithm operates
on each letter of the plaintext message independently.
Stream ciphers can also function as a type of block
cipher. In such operations there is a buffer that fills up
to real-time data that is then encrypted as a block and
transmitted to the recipient.
49. Confusion and Diffusions
Cryptographic algorithms rely on two basic operations
to obscure plaintext messages— confusion and
diffusion.
Confusion occurs when the relationship between the
plain text and the key is so complicated that an
attacker can’t merely continue altering the plain text
and analyzing the resulting ciphertext to determine the
key.
Diffusion occurs when a change in the plain text
results in multiple changes spread throughout the
ciphertext. Consider, for example, a cryptographic
algorithm that first performs a complex substitution and
then uses transposition to rearrange the characters of
the substituted ciphertext.
50. Modern Cryptography
Modern cryptosystems use computationally complex
algorithms and long cryptographic keys to meet the
cryptographic goals of confidentiality, integrity,
authentication, and nonrepudiation.
51. Cryptographic Keys
Instead of relying on secret algorithms, modern
cryptosystems rely on the secrecy of one or more
cryptographic keys used to personalize the algorithm
for specific users or groups of users.
52. Symmetric Key Algorithms
Symmetric key algorithms rely on a “shared secret”
encryption key that is distributed to all members who
participate in the communications. This key is used by
all parties to both encrypt and decrypt messages, so
the sender and the receiver both possess a copy of
the shared key.
53. Asymmetric Key Algorithms
Asymmetric key algorithms, also known as public key
algorithms, provide a solution to the weaknesses of
symmetric key encryption. In these systems, each user
has two keys: a public key, which is shared with all
users, and a private key, which is kept secret and
known only to the user.
54. Hashing Algorithms
Public key cryptosystems can provide digital signature
capability when used in conjunction with a message digest.
Message digests are summaries of a message’s content
(not unlike a file checksum) produced by a hashing
algorithm. It’s extremely difficult, to derive a message from
an ideal hash function, and unlikely that two messages will
produce the same hash value.
The following are some of the more common hashing
algorithms are;
Message Digest 2 (MD2)
Message Digest 5 (MD5)
Secure Hash Algorithm (SHA-0, SHA-1, and SHA-2)
Hashed Message Authentication Code (HMAC)
55. Symmetric Cryptographic Types
Some several common symmetric cryptosystems are;
Data Encryption Standard (DES)
Triple DES (3DES)
International Data Encryption Algorithm (IDEA)
Blowfish
Skipjack
Advanced Encryption Standard (AES)
56. Data Encryption Standard
DES was superseded by the Advanced Encryption
Standard in December 2001. It is still important to
understand DES because it is the building block of Triple
DES (3DES), a strong encryption algorithm.
DES is a 64-bit block cipher that has five modes of
operation:
Electronic Codebook (ECB) mode
Cipher Block Chaining (CBC) mode
Cipher Feedback (CFB) mode
Output Feedback (OFB) mode
Counter (CTR) mode
The key used by DES is 56 bits long. DES uses a long
series of exclusive OR (XOR) operations to generate the
ciphertext.
57. Electronic CodeBook Mode
Electronic Codebook (ECB) mode is the simplest
mode and the least secure. Each time the algorithm
processes a 64-bit block, it simply encrypts the block
using the chosen secret key.
If an enemy were eavesdropping on the
communications, they could simply build a “code book”
of all the possible encrypted values.
In everyday use, ECB is used only for exchanging
small amounts of data, such as keys and parameters
used to initiate other DES modes as well as the cells in
a database.
58. Cipher BlockChaining Mode
Each block of unencrypted text is XORed with the
block of ciphertext immediately preceding it before it is
encrypted using the DES algorithm. The decryption
process simply decrypts the ciphertext and reverses
the XOR operation. CBC implements an IV and XORs
it with the first block of the message, producing a
unique output every time the operation is performed.
One important consideration when using CBC mode is
that errors propagate, if one block is corrupted during
transmission, it becomes impossible to decrypt that
block and the next block as well.
59. Cipher FeedBack Mode
CFB operates against data produced in real time.
However, instead of breaking a message into blocks, it
uses memory buffers of the same block size. As the
buffer becomes full, it is encrypted and then sent to the
recipient(s). Then the system waits for the next buffer
to be filled as the new data is generated before it is in
turn encrypted and then transmitted.
60. Output FeedBack Mode
The major advantages of OFB mode are that there is
no chaining function and transmission errors do not
propagate to affect the decryption of future blocks.
For the first encrypted block, an initialization vector is
used to create the seed value. Future seed values are
derived by running the DES algorithm on the previous
seed value.
61. Counter Mode
DES that is run in Counter (CTR) mode uses a stream
cipher similar to that used in CFB and OFB modes.
However, instead of creating the seed value for each
encryption/decryption operation from the results of the
previous seed values, it uses a simple counter that
increments for each operation. As with OFB mode,
errors do not propagate in CTR mode.
62. Triple DES
An adapted version of DES, Triple DES (3DES), uses
the same algorithm to produce a more secure
encryption.
There are four versions of 3DES.
The first simply encrypts the plain text three times,
using three different keys: K1 , K2 , and K3 . It is
known as DES-EEE3 mode (the Es indicate that there
are three encryption operations, whereas the numeral
3 indicates that three different keys are used).
DES-EEE3 has an effective key length of 168 bits and
it is expressed as;
E(K1,E(K2,E(K3,P)))
63. Triple DES
The second variant (DES-EDE3) also uses three
keys but replaces the second encryption operation
with a decryption operation: E(K1,D(K2,E(K3,P)))
The third version of 3DES (DES-EEE2) uses only
two keys, K1 and K2 , as follows:
E(K1,E(K2,E(K1,P)))
The fourth variant of 3DES (DES-EDE2) also uses
two keys but uses a decryption operation in the
middle: E(K1,D(K2,E(K1,P)))
Both the third and fourth variants have an effective key
length of 112 bits.
64. International Data Encryption
Algorithm
The IDEA block cipher was developed in response to
complaints about the insufficient key length of the DES
algorithm. Like DES, IDEA operates on 64-bit blocks of
plain text/ciphertext. However, it begins its operation
with a 128-bit key. This key is broken up in a series of
operations into 52 16-bit subkeys.
IDEA is capable of operating in the same five modes
used by DES: ECB, CBC, CFB, OFB,
One popular implementation of IDEA is found in Phil
Zimmerman’s popular Pretty Good Privacy (PGP)
secure email package.
65. BlowFish
Bruce Schneier’s Blowfish block cipher is another
alternative to DES and IDEA. Like its predecessors,
Blowfish operates on 64-bit blocks of text. However, it
extends IDEA’s key strength even further by allowing
the use of variable-length keys ranging from a
relatively insecure 32 bits to an extremely strong 448
bits.
Blowfish encryption is built into a number of
commercial software products and operating systems.
A number of Blowfish libraries are also available for
software developers.
66. SkipJack
The Skipjack algorithm was approved for use by the
US government in Federal Information Processing
Standard (FIPS) 185, the Escrowed Encryption
Standard (EES). Like many block ciphers, Skipjack
operates on 64-bit blocks of text. It uses an 80-bit key
and supports the same four modes of operation
supported by DES.
When law enforcement authorities obtain legal
authorization, they contact the two agencies, obtain
the pieces of the key, and are able to decrypt
communications between the affected parties.
67. Advanced Encryption Standard
The National Institute of Standards and Technology (NIST)
announced that the Rijndael (pronounced “rhine-doll”) block
cipher had been chosen as the replacement for DES. In
November 2001, NIST released FIPS 197, which mandated
the use of AES/Rijndael for the encryption of all sensitive
but unclassified data.
The AES cipher allows the use of three key strengths: 128
bits, 192 bits, and 256 bits. AES only allows the
processing of 128-bit blocks.
The number of encryption rounds depends on the key
length chosen:
128-bit keys require 10 rounds of encryption
192-bit keys require 12 rounds of encryption
256-bit keys require 14 rounds of encryption
68. Symmetric key Management
Because cryptographic keys contain information
essential to the security of the cryptosystem, it is
incumbent upon cryptosystem users and
administrators to take extraordinary measures to
protect the security of the keying material. These
security measures are collectively known as key
management practices. Some Practices include;
1) Creation & Distribution of keys:
Secure distribution of the secret keys required to
operate the algorithms. The three main methods used
to exchange secret keys securely are offline
distribution, public key encryption, and the Diffie-
Hellman key exchange algorithm.
69. Diffie-Hellman key Exchange
Algorithm
The Diffie-Hellman algorithm represented a major advance in the
state of cryptographic science when it was released in 1976. The
algorithm works as follows:
The communicating parties (we’ll call them Richard and Sue)
agree on two large numbers: p (which is a prime number) and
g (which is an integer) such that 1 < g < p.
Richard chooses a random large integer r and performs the
following calculation: R = gr mod p.
Sue chooses a random large integer s and performs the
following calculation: S = gs mod p.
Richard sends R to Sue and Sue sends S to Richard.
Richard then performs the following calculation: K = Sr mod p.
Sue then performs the following calculation: K = Rs mod p
At this point, Richard and Sue both have the same value, K, and
can use this for secret key communication between the two
parties.
70. Key Escrow & Recovery
There are two major approaches to key escrow that
have been proposed over the past decade:
Fair Cryptosystems: In this escrow approach, the
secret keys used in a communication are divided into
two or more pieces, each of which is given to an
independent third party. Each of these pieces is
useless on its own but may be recombined to obtain
the secret key.
Escrowed Encryption Standard: This escrow
approach provides the government with a
technological means to decrypt ciphertext. It’s highly
unlikely that government regulators will ever overcome
the legal and privacy hurdles necessary to implement
key escrow on a widespread basis.
71. Cryptographic Life Cycle
All cryptographic systems have a limited life span.
Moore’s law, a commonly cited trend in the
advancement of computing power, states that the
processing capabilities of a state-of-the-art
microprocessor will double approximately every two
years.
Security professionals must keep this cryptographic
life cycle in mind when selecting an encryption
algorithm and have appropriate governance controls in
place to ensure that the algorithms, protocols, and key
lengths.
72. Cryptographic Life Cycle
Security professionals can use the following algorithm
and protocol governance controls:
Specifying the cryptographic algorithms (such as
AES, 3DES, and RSA) acceptable for use in an
organization.
Identifying the acceptable key lengths for use with
each algorithm based on the sensitivity of
information transmitted.
Enumerating the secure transaction protocols (such
as SSL and TLS) that may be used.