1) The document proposes a hybrid 128-bit key AES-DES algorithm to enhance data security and transmission security for next generation networks.
2) It discusses some weaknesses in the AES encryption algorithm against algebraic cryptanalysis and outlines a hybrid approach that combines AES and DES algorithms.
3) The hybrid approach integrates the AES encryption process within the Feistel network structure of DES, using AES transformations like byte substitution and shift rows within each round of the DES Feistel network. This is intended to strengthen security by combining the advantages of both algorithms while reducing individual weaknesses.
A new cryptosystem with four levels of encryption and parallel programmingcsandit
Evolution in the communication systems has changed the paradigm of human life on this planet.
The growing network facilities for the masses have converted this world to a village (or may be
even smaller entity of human accommodation) in a sense that every part of the world is
reachable for everyone in almost no time. But this fact is also not an exception for coins having
two sides. With increasing use of communication networks the various threats to the privacy,
integrity and confidentiality of the data sent over the network are also increasing, demanding
the newer and newer security measures to be implied. The ancient techniques of coded
messages are imitated in terms of new software environments under the domain of
cryptography. The cryptosystems provide a means for the secured transmission of data over an
unsecured channel by providing encoding and decoding functionalities. This paper proposes a
new cryptosystem based on four levels of encryption. The system is suitable for communication
within the trusted groups.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
A new cryptosystem with four levels of encryption and parallel programmingcsandit
Evolution in the communication systems has changed the paradigm of human life on this planet.
The growing network facilities for the masses have converted this world to a village (or may be
even smaller entity of human accommodation) in a sense that every part of the world is
reachable for everyone in almost no time. But this fact is also not an exception for coins having
two sides. With increasing use of communication networks the various threats to the privacy,
integrity and confidentiality of the data sent over the network are also increasing, demanding
the newer and newer security measures to be implied. The ancient techniques of coded
messages are imitated in terms of new software environments under the domain of
cryptography. The cryptosystems provide a means for the secured transmission of data over an
unsecured channel by providing encoding and decoding functionalities. This paper proposes a
new cryptosystem based on four levels of encryption. The system is suitable for communication
within the trusted groups.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
There is great research in the field of data security these days. Storing information digitally in the cloud and transferring it over the internet proposes risks of disclosure and unauthorized access, thus users, organizations and businesses are adapting new technology and methods to protect their data from breaches. In this paper, we introduce a method to provide higher security for data transferred over the internet, or information based in the cloud. The introduced method for the most part depends on the Advanced Encryption Standard (AES) algorithm. Which is currently the standard for secret key encryption. A standardized version of the algorithm was used by The Federal Information Processing Standard 197 called Rijndael for the Advanced Encryption Standard. The AES algorithm processes data through a combination of Exclusive-OR operations (XOR), octet substitution with an S-box, row and column rotations, and a MixColumn operations. The fact that the algorithm could be easily implemented and run on a regular computer in a reasonable amount of time made it highly favorable and successful.
In this paper, the proposed method provides a new dimension of security to the AES algorithm by securing the key itself such that even when the key is disclosed, the text cannot be deciphered. This is done by enciphering the key using Output Feedback Block Mode Operation. This introduces a new level of security to the key in a way in which deciphering the data requires prior knowledge of the key and the algorithm used to encipher the key for the purpose of deciphering the transferred text.
Keywords: Keywords: Keywords: Keywords: Keywords: Keywords: Keywords:
A New hybrid method in watermarking using DCT and AESIJERD Editor
In this paper I'm trying to make a combination between the encryption by using one of the most
powerful algorithm called Advanced Encryption Standard (AES) to encrypt a secret message another word logo
and then embed it in the digital image in frequency domain by using the Discrete Cosine Transform (DCT) in
low frequency to increase the robustness and then applying some attacks to check it.
Using Cipher Key to Generate Dynamic S-Box in AES Cipher SystemCSCJournals
The Advanced Encryption Standard (AES) is using in a large scale of applications that need to protect their data and information. The S-Box component that used in AES is fixed, and not changeable. If we can generate this S-Box dynamically, we increase the cryptographic strength of AES cipher system. In this paper we intend to introduce new algorithm that generate S-Box dynamically from cipher key. We describe how S-Box can be generated dynamically from cipher key and finally analyze the results and experiments.
Nearest Prime Cipher for Data Confidentiality and IntegrityEswar Publications
Communication is the process of transmitting information from source to destination. The information exchanged between sender and receiver through the proper channel. The information should not be stolen by unauthorized parties like hackers while sending or receiving via channel. To avoid this stealing of the information cryptography techniques are used. The key is playing prominent role in cryptography. This paper proposes a novel method for key generation by using nearest primes. Further 2’s complement and logical operations are
used in encryption and decryption process. The final cipher text is generated by representing the intermediate cipher in matrix form and then read by column wise.
The Advanced Encryption Standard (AES) is a specification for the encryption of electronic data also called Rijndael. The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data. Hardware-based cryptography is used for authentication of users and of software updates and installations. Software implementations can generally not be used for this, as the cryptographic keys are stored in the PC memory during execution, and are vulnerable to malicious codes. Hardware-based encryption products can also vary in the level of protection they provide against brute force rewind attacks, Offline parallel attacks, or other cryptanalysis attacks. The algorithm was implemented in FPGA due to its flexibility and reconfiguration capability. A reconfigurable device is very convenient for a cryptography algorithm since it allows cheap and quick alterations. The implementation of pipelined cryptography hardware was used to improve performance in order to achieve higher throughput and greater parallelism. The AES hardware was implemented in three modules contains of the encryption, the decryption and the key expansion module.
International Data Encryption Algorithm (IDEA) is one of the encryption algorithms that is widely used for security purpose. IDEA block cipher operates with 64-bit plain text block and 64-bit cipher text block, and a 128-bit key controls it. The fundamental design of the algorithm is using three different algebraic operations: bitwise Exclusive OR, multiplication modulo, and addition modulo. Having the largest number of weak keys is one of the drawbacks of IDEA. In addition, a new attack during round six of IDEA’s operations has been detected. In this paper, we propose and describe the new design and preliminary implementation of a more secure encryption algorithm based on IDEA, and it is named DS-IDEA. Increasing the size of the key from 128 bits to 512 bits will increase the complexity of the algorithm. The algorithm’s complexity is increased by increasing the amount of diffusion (multiplicative additive block) in a single round. It is implemented to provide better security to the user’s password within the Online Password Management System (OPMS) in order to protect the user’s data within the database from hackers and other forms of unauthorized access.
New modification on feistel DES algorithm based on multi-level keys IJECEIAES
The data encryption standard (DES) is one of the most common symmetric encryption algorithms, but it experiences many problems. For example, it uses only one function (XOR) in the encryption process, and the combination of data is finite because it occurs only twice and operates on bits. This paper presents a new modification of the DES to overcome these problems. This could be done through adding a new level of security by increasing the key space (using three keys) during the 16 rounds of the standard encryption algorithm and by replacing the predefined XOR operation with a new # operation. Our proposed algorithm uses three keys instead of one. The first key is the input key used for encrypting and decrypting operations. The second key is used for determining the number of bits, while the third key is used for determining the table numbers, which are from 0 to 255. Having evaluated the complexity of our proposed algorithm, the results show that it is the most complex compared with the well-known DES and other modified algorithms. Consequently, in our proposed algorithm, the attacker try a number of attempts 2 1173 at minimum to decrypt the message. This means that the proposed DES algorithm will increase the security level of the well-known DES.
Minor Project- AES Implementation in VerilogHardik Manocha
This presentation described about the Minor project I worked on for partial fulfillment of Bachelors Degree in G B Pant Engineering College. Presentation consisted of Advanced Encryption Standard (AES) and its implementation in Verilog. Different steps of the algorithm are presented.
Advanced Encryption Standard (AES) algorithm is considered as a secured algorithm. Still, some security issues lie in the S-Box and the key used. In this paper, we have tried to give focus on the security of the key used. Here, the proposed modified algorithms for the AES have been simulated and tested with different chaotic variations such as 1-D logistic chaos equation, cross chaos equation as well as combination of both. For the evaluation purpose, the CPU time has been taken as the parameter. Though the variations of AES algorithms are taking some more time as compared to the standard AES algorithm, still the variations can be taken into consideration in case of more sensitive information. As we are giving more security to
the key used for AES algorithm, our proposed algorithms are very much secured from unauthorized people.
Introduction For seq2seq(sequence to sequence) and RNNHye-min Ahn
This is my slides for introducing sequence to sequence model and Recurrent Neural Network(RNN) to my laboratory colleagues.
Hyemin Ahn, @CPSLAB, Seoul National University (SNU)
A Universal Session Based Bit Level Symmetric Key Cryptographic Technique to ...IJNSA Journal
In this technical paper a session based symmetric key cryptographic technique, termed as SBSKCT, has been proposed. This proposed technique is very secure and suitable for encryption of large files of any type. SBSKCT considers the plain text as a string with finite no. of binary bits. This input binary string is broken down into blocks of various sizes (of 2k
order where k = 3, 4, 5, ….). The encrypted binary string
is formed by shifting the bit position of each block by a certain values for a certain number of times and from this string cipher text is formed. Combination of values of block length, no. of blocks and no. of iterations generates the session based key for SBSKCT. For decryption the cipher text is considered as
binary string. Using the session key information, this binary string is broken down into blocks. The decrypted binary string is formed by shifting the bit position of each block by a certain values for a certain number of times and from this string plain text is reformed. A comparison of SBSKCT with existing and industrially accepted TDES and AES has been done.
Design and Analysis of Parallel AES Encryption and Decryption Algorithm for M...iosrjce
This paper presents information on AES Encryption and Decryption for multi processors. In this
paper AES algorithm is used. The AES algorithm is a round based algorithm. The round based algorithm is
used to provide security to the information. In AES algorithm there are different types of keys, they are 128,192
and 256 bits. These bits are used to encrypt and decrypt the information. In this paper 128bits are used. In this
paper the main functional blocks are key generation, encryption and decryption. In order produce a new key sub
byte, rotate word, round constant and add round key operations are used. In order to convert plain text to
cipher message the sub bytes, shift rows, mix column and add round key operations are used. By doing these
operations the cipher information is obtained. This cipher will be given to the decryption and it is the total
reverse process of encryption. After completion of reverse process the outcome is original information.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
A Cryptographic Hardware Revolution in Communication Systems using Verilog HDLidescitation
Advanced Encryption Standard (AES), is an
advancement of Federal Information Processing Standard
(FIPS) which is an initiated Process Standard of NIST. The
AES specifies the Rijndael algorithm, in which a symmetric
block cipher that processes fixed 128 bit data blocks using
cipher keys with different lengths of 128, 192 and 256 bits.
The earliest Rijndael algorithm had the advantage of
combining both data block sizes of 128, 192 and 256 bits with
any key lengths. AES can be programmed in pure hardware
Verilog HDL, Which includes Multiplexer to enhance more
secure to Cipher text. The results indicate that the hardware
implementation proposed in this project is Decrementing
Utilization of resource and power consumption of 113 mW
than other implementation. Using FPGA lead to reliability on
source modulations. This project presents the AES algorithm
with regard to FPGA and Verilog HDL. The software used for
Simulation is ModelSim-Altera 6.3g_p1 (Quartus II 8.1).
Synthesis and implementation of the code is carried out on
Xilinx ISE 13.4 (XC6VCX240T) device is used for hardware
evaluation.
There is great research in the field of data security these days. Storing information digitally in the cloud and transferring it over the internet proposes risks of disclosure and unauthorized access, thus users, organizations and businesses are adapting new technology and methods to protect their data from breaches. In this paper, we introduce a method to provide higher security for data transferred over the internet, or information based in the cloud. The introduced method for the most part depends on the Advanced Encryption Standard (AES) algorithm. Which is currently the standard for secret key encryption. A standardized version of the algorithm was used by The Federal Information Processing Standard 197 called Rijndael for the Advanced Encryption Standard. The AES algorithm processes data through a combination of Exclusive-OR operations (XOR), octet substitution with an S-box, row and column rotations, and a MixColumn operations. The fact that the algorithm could be easily implemented and run on a regular computer in a reasonable amount of time made it highly favorable and successful.
In this paper, the proposed method provides a new dimension of security to the AES algorithm by securing the key itself such that even when the key is disclosed, the text cannot be deciphered. This is done by enciphering the key using Output Feedback Block Mode Operation. This introduces a new level of security to the key in a way in which deciphering the data requires prior knowledge of the key and the algorithm used to encipher the key for the purpose of deciphering the transferred text.
Keywords: Keywords: Keywords: Keywords: Keywords: Keywords: Keywords:
A New hybrid method in watermarking using DCT and AESIJERD Editor
In this paper I'm trying to make a combination between the encryption by using one of the most
powerful algorithm called Advanced Encryption Standard (AES) to encrypt a secret message another word logo
and then embed it in the digital image in frequency domain by using the Discrete Cosine Transform (DCT) in
low frequency to increase the robustness and then applying some attacks to check it.
Using Cipher Key to Generate Dynamic S-Box in AES Cipher SystemCSCJournals
The Advanced Encryption Standard (AES) is using in a large scale of applications that need to protect their data and information. The S-Box component that used in AES is fixed, and not changeable. If we can generate this S-Box dynamically, we increase the cryptographic strength of AES cipher system. In this paper we intend to introduce new algorithm that generate S-Box dynamically from cipher key. We describe how S-Box can be generated dynamically from cipher key and finally analyze the results and experiments.
Nearest Prime Cipher for Data Confidentiality and IntegrityEswar Publications
Communication is the process of transmitting information from source to destination. The information exchanged between sender and receiver through the proper channel. The information should not be stolen by unauthorized parties like hackers while sending or receiving via channel. To avoid this stealing of the information cryptography techniques are used. The key is playing prominent role in cryptography. This paper proposes a novel method for key generation by using nearest primes. Further 2’s complement and logical operations are
used in encryption and decryption process. The final cipher text is generated by representing the intermediate cipher in matrix form and then read by column wise.
The Advanced Encryption Standard (AES) is a specification for the encryption of electronic data also called Rijndael. The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data. Hardware-based cryptography is used for authentication of users and of software updates and installations. Software implementations can generally not be used for this, as the cryptographic keys are stored in the PC memory during execution, and are vulnerable to malicious codes. Hardware-based encryption products can also vary in the level of protection they provide against brute force rewind attacks, Offline parallel attacks, or other cryptanalysis attacks. The algorithm was implemented in FPGA due to its flexibility and reconfiguration capability. A reconfigurable device is very convenient for a cryptography algorithm since it allows cheap and quick alterations. The implementation of pipelined cryptography hardware was used to improve performance in order to achieve higher throughput and greater parallelism. The AES hardware was implemented in three modules contains of the encryption, the decryption and the key expansion module.
International Data Encryption Algorithm (IDEA) is one of the encryption algorithms that is widely used for security purpose. IDEA block cipher operates with 64-bit plain text block and 64-bit cipher text block, and a 128-bit key controls it. The fundamental design of the algorithm is using three different algebraic operations: bitwise Exclusive OR, multiplication modulo, and addition modulo. Having the largest number of weak keys is one of the drawbacks of IDEA. In addition, a new attack during round six of IDEA’s operations has been detected. In this paper, we propose and describe the new design and preliminary implementation of a more secure encryption algorithm based on IDEA, and it is named DS-IDEA. Increasing the size of the key from 128 bits to 512 bits will increase the complexity of the algorithm. The algorithm’s complexity is increased by increasing the amount of diffusion (multiplicative additive block) in a single round. It is implemented to provide better security to the user’s password within the Online Password Management System (OPMS) in order to protect the user’s data within the database from hackers and other forms of unauthorized access.
New modification on feistel DES algorithm based on multi-level keys IJECEIAES
The data encryption standard (DES) is one of the most common symmetric encryption algorithms, but it experiences many problems. For example, it uses only one function (XOR) in the encryption process, and the combination of data is finite because it occurs only twice and operates on bits. This paper presents a new modification of the DES to overcome these problems. This could be done through adding a new level of security by increasing the key space (using three keys) during the 16 rounds of the standard encryption algorithm and by replacing the predefined XOR operation with a new # operation. Our proposed algorithm uses three keys instead of one. The first key is the input key used for encrypting and decrypting operations. The second key is used for determining the number of bits, while the third key is used for determining the table numbers, which are from 0 to 255. Having evaluated the complexity of our proposed algorithm, the results show that it is the most complex compared with the well-known DES and other modified algorithms. Consequently, in our proposed algorithm, the attacker try a number of attempts 2 1173 at minimum to decrypt the message. This means that the proposed DES algorithm will increase the security level of the well-known DES.
Minor Project- AES Implementation in VerilogHardik Manocha
This presentation described about the Minor project I worked on for partial fulfillment of Bachelors Degree in G B Pant Engineering College. Presentation consisted of Advanced Encryption Standard (AES) and its implementation in Verilog. Different steps of the algorithm are presented.
Advanced Encryption Standard (AES) algorithm is considered as a secured algorithm. Still, some security issues lie in the S-Box and the key used. In this paper, we have tried to give focus on the security of the key used. Here, the proposed modified algorithms for the AES have been simulated and tested with different chaotic variations such as 1-D logistic chaos equation, cross chaos equation as well as combination of both. For the evaluation purpose, the CPU time has been taken as the parameter. Though the variations of AES algorithms are taking some more time as compared to the standard AES algorithm, still the variations can be taken into consideration in case of more sensitive information. As we are giving more security to
the key used for AES algorithm, our proposed algorithms are very much secured from unauthorized people.
Introduction For seq2seq(sequence to sequence) and RNNHye-min Ahn
This is my slides for introducing sequence to sequence model and Recurrent Neural Network(RNN) to my laboratory colleagues.
Hyemin Ahn, @CPSLAB, Seoul National University (SNU)
A Universal Session Based Bit Level Symmetric Key Cryptographic Technique to ...IJNSA Journal
In this technical paper a session based symmetric key cryptographic technique, termed as SBSKCT, has been proposed. This proposed technique is very secure and suitable for encryption of large files of any type. SBSKCT considers the plain text as a string with finite no. of binary bits. This input binary string is broken down into blocks of various sizes (of 2k
order where k = 3, 4, 5, ….). The encrypted binary string
is formed by shifting the bit position of each block by a certain values for a certain number of times and from this string cipher text is formed. Combination of values of block length, no. of blocks and no. of iterations generates the session based key for SBSKCT. For decryption the cipher text is considered as
binary string. Using the session key information, this binary string is broken down into blocks. The decrypted binary string is formed by shifting the bit position of each block by a certain values for a certain number of times and from this string plain text is reformed. A comparison of SBSKCT with existing and industrially accepted TDES and AES has been done.
Design and Analysis of Parallel AES Encryption and Decryption Algorithm for M...iosrjce
This paper presents information on AES Encryption and Decryption for multi processors. In this
paper AES algorithm is used. The AES algorithm is a round based algorithm. The round based algorithm is
used to provide security to the information. In AES algorithm there are different types of keys, they are 128,192
and 256 bits. These bits are used to encrypt and decrypt the information. In this paper 128bits are used. In this
paper the main functional blocks are key generation, encryption and decryption. In order produce a new key sub
byte, rotate word, round constant and add round key operations are used. In order to convert plain text to
cipher message the sub bytes, shift rows, mix column and add round key operations are used. By doing these
operations the cipher information is obtained. This cipher will be given to the decryption and it is the total
reverse process of encryption. After completion of reverse process the outcome is original information.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
A Cryptographic Hardware Revolution in Communication Systems using Verilog HDLidescitation
Advanced Encryption Standard (AES), is an
advancement of Federal Information Processing Standard
(FIPS) which is an initiated Process Standard of NIST. The
AES specifies the Rijndael algorithm, in which a symmetric
block cipher that processes fixed 128 bit data blocks using
cipher keys with different lengths of 128, 192 and 256 bits.
The earliest Rijndael algorithm had the advantage of
combining both data block sizes of 128, 192 and 256 bits with
any key lengths. AES can be programmed in pure hardware
Verilog HDL, Which includes Multiplexer to enhance more
secure to Cipher text. The results indicate that the hardware
implementation proposed in this project is Decrementing
Utilization of resource and power consumption of 113 mW
than other implementation. Using FPGA lead to reliability on
source modulations. This project presents the AES algorithm
with regard to FPGA and Verilog HDL. The software used for
Simulation is ModelSim-Altera 6.3g_p1 (Quartus II 8.1).
Synthesis and implementation of the code is carried out on
Xilinx ISE 13.4 (XC6VCX240T) device is used for hardware
evaluation.
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.
Security Analysis of AES and Enhancing its Security by Modifying S-Box with a...IJCNCJournal
Secured and opportune transmission of data alwaysis a significant feature for any organization. Robust
encryption techniques and algorithms always facilitate in augmenting secrecy, authentication and
reliability of data. At present, Advanced Encryption Standard (AES) patronized by NIST is the most secure
algorithm for escalating the confidentiality of data. This paper mainly focuses on an inclusive analysis
related to the security of existing AES algorithm and aim to enhance the level security of this algorithm.
Through some modification of existing AES algorithm by XORing an additional byte with s-box value, we
have successfully increased the Time Security and Strict Avalanche Criterion. We have used random
additional key for increasing security. Since this key is random, result of security measurement sometimes
fluctuates.
Comparison of AES and DES Algorithms Implemented on Virtex-6 FPGA and Microbl...IJECEIAES
Encryption algorithms play a dominant role in preventing unauthorized access to important data. This paper focus on the implementations of Data Encryption Standard (DES) and Advanced Encryption Standard (AES) algorithms on Microblaze soft core Processor and also their implementations on XC6VLX240t FPGA using Verilog Hardware Description language. This paper also gives a comparison of the issues related to the hardware and software implementations of the two cryptographic algorithms.
IJCER (www.ijceronline.com) International Journal of computational Engineerin...ijceronline
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Design and Implementation A different Architectures of mixcolumn in FPGAVLSICS Design
This paper details Implementation of the Encryption algorithm AES under VHDL language In FPGA by using different architecture of mixcolumn. We then review this research investigates the AES algorithm in FPGA and the Very High Speed Integrated Circuit Hardware Description language (VHDL). Altera Quartus II software is used for simulation and optimization of the synthesizable VHDL code. The set of transformations of both Encryptions and decryption are simulated using an iterative design approach in order to optimize the hardware consumption. Altera Cyclone III Family devices are utilized for hardware evaluation.
Design and Implementation A different Architectures of mixcolumn in FPGA
icwet1097
1. International Conference & Workshop on Recent Trends in Technology, (TCET) 2012
Proceedings published in International Journal of Computer Applications® (IJCA)
1
Security Enhancement Algorithms for Data
Transmission for Next Generation Networks
Vikas Kaul
TCET, Mumbai
S K Narayankhedkar
SIGCOE. Mumbai
S Achrekar, S Agarwal, P
Goyal, TCET,Mumbai
ABSTRACT
As the speed of processors and knowledge about cryptanalysis
goes on increasing day by day, the original encryption
methods prove to be insufficient for better security. As large
amount of data is transmitted over the network, it is
preliminary to secure all types of data before sending it.. The
problem with AES, most extensively used encryption, is that
it uses many multivariate equations which are linear in nature.
Thus it can be broken using algebraic cryptanalysis. This
provides a serious threat as AES was considered to be
unbreakable and thus it was used in many encryption systems.
The paper presents the design and implementation of a hybrid
based 128 bit key AES-DES algorithm as a security
enhancement.
Keywords
SBox, XOR, Cipher, Key matrix, Hybrid AES DES, Chaos,
Feistal network.
INTRODUCTION
We have chosen integrating AES with Feistal network of DES
so as to enhance security. The paper outlines the possible
weaknesses within the current AES encryption algorithm
especially against algebraic based cryptanalysis.
Understanding the need to minimize algebraic attacks into the
AES, it proposes the idea on integrating AES within the
Feistal network of DES, hence resulting into the development
of the Hybrid AES-DES algorithm. The levels of Feistal
network as applied into the Hybrid AES-DES structure are
retrospective to Quality of Service (QoS) needs.
The main idea of using a hybrid approach is that we combine
two algorithms in such a way that the disadvantages of both of
them are reduced. Hence we get a system which is much
difficult to break by cryptanalysis. Thus the hybrid system
will take a 256 bit data and 128 bit key.
Cryptanalysis of AES
AES is based on a design principle known as a Substitution
permutation network. It is fast in both software and
hardware.Unlike its predecessor DES, AES does not use a
Feistel network.
AES has a fixed block size of 128 bits and a key size of 128,
192, or 256 bits, whereas Rijndael can be specified with block
and key sizes in any multiple of 32 bits, with a minimum of
128 bits. The blocksize has a maximum of 256 bits, but the
keysize has no theoretical maximum.
AES operates on a 4×4 column-major order matrix of bytes,
termed the state (versions of Rijndael with a larger block size
have additional columns in the state). Most AES calculations
are done in a special finite field..The AES cipher is specified
as a number of repetitions of transformation rounds that
convert the input plaintext into the final output of ciphertext.
Each round consists of several processing steps, including one
that depends on the encryption key. A set of reverse rounds
are applied to transform ciphertext back into the original
plaintext using the same encryption key.
AES Implementation:-
A byte in Rijndael is a group of 8 bits and is the basic data
unit for all cipher operations. Such bytes are interpreted as
finite field elements using polynomial representation, where a
byte b with bits b0, b1,...b7 represents the finite field
elements. The conversion from plain text to State Matrix is
shown in Figure 1.As discussed, bytes are can be represented
as polynomials. Finite field operations like addition and
multiplication are required for key scheduling and rounding.
The addition of two finite field elements is achieved by
adding the coefficients for corresponding powers in their
polynomial representations, this addition being performed in
GF(2), that is, modulo 2, so that 1+ 1 = 0. Addition is nothing
but performing XOR between two expressions .Finite field
multiplication is more difficult than addition and is achieved
by multiplying the polynomials for the two elements
concerned and collecting like powers of x in the result. Since
each polynomial can have powers of x up to 7, the result can
have powers of x up to 14 and will no longer fit within a
single byte. This is overcome by using a field generator. The
product is divided by this field generator and the remainder is
taken asthe result. Since there are 256 possible polynomials, a
look uptable can be created for a specific field generator. So
the lookup table will have 256 * 256 entries .scheduling:
The round keys are derived from the cipherkey by means of a
key schedule with each round requiring Ncwords of key data.
For 128-bits keys the key scheduling operates intrinsically on
blocks of 4 32-bits words; we can calculate one new round
key from the previous one,denote the ithword of the actual
round key with K[i], where 0¡i¡4, and the ithword of the next
round key with K[i]. K[0] is computed by anXOR between
K[0], a constant r (field generator) and K[3], the latter being
2. International Conference & Workshop on Recent Trends in Technology, (TCET) 2012
Proceedings published in International Journal of Computer Applications® (IJCA)
2
pre rotated and transformed. The other three words K[1], K[2]
and K[3] are calculated as K[i] = K[i] . K[i - 1].
Rounding: At the start of the cipher the cipher input is copied
into the internal state using the conventions described
before(Figure 1). An initial round key is then added and the
state isthen transformed by iterating a round function in a
number of cycles.The steps involvedin AES are shown in
Illustration1. It is the algorithm as rinjdael suggested.
Round Function: One round is termed as a cycle and each
cycle has four steps. Each step of transformation is described
below. Add Round Key: This is the first step of
transformation. The Xor Round Key function declared in
Illustration 1 has to perform a bitwise xor of the state matrix
and the round key matrix.
Sub-Bytes :Transformation: Inverse of the state matrix is
found here and affine transformation is performed.
Shift Rows: The ShiftRows transformation operates
individually on each of the last three rows of the state matrix
by cyclically shifting the bytes in the row. The second row is
shift done time to the left, third row shifted two times and
fourth rows shifted three times.
Mix Columns: The mix columns transformation computes
the new state matrix S by left-multiplying the current state
matrix S by the polynomial matrix P:S = P o S where P is a
fixedmatrix as shown below.
The Advanced Encryption Standard (AES), the block
cipher ratified as a standard by National Institute of Standards
and Technology of the United States (NIST), was chosen
using a process markedly more open and transparent than its
predecessor, the aging Data Encryption Standard (DES). This
process won plaudits from the
open cryptographic community, and helped to increase
confidence in the security of the winning algorithm from
those who were suspicious of backdoors in the predecessor,
DES.
Figure 1 (a) major functions of aes
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2 . DES
DES is the block cipher — an algorithm that takes a
fixed-length string of plaintext bits and transforms it
through a series of complicated operations into another
ciphertext bitstring of the same length. In the case of
DES, the block size is 64 bits. DES also uses a key to
customize the transformation, so that decryption can
supposedly only be performed by those who know the
particular key used to encrypt. The key ostensibly
consists of 64 bits; however, only 56 of these are
actually used by the algorithm. Eight bits are used
solely for checking parity, and are thereafter discarded.
Hence the effective key length is 56 bits, and it is never
quoted as such. Every 8th bit of the selected key is
discarded, that is, positions 8, 16, 24, 32, 40, 48, 56, 64
are removed from the 64 bit key leaving behind only the
56 bit key.
Fig 1(b) One round of DES
3. Concept of Hybrid AES DES
Mathematically, the idea of a hybrid based AES-DES can be
construed with reference to basic DES Feistel equations. The
repetition of these equations is based on the number of rounds
as adapted by the Feistel network, which in the case of DES
was standardized at 16. However, by incorporating the AES
within this yield the following results.
Ln =Rn-1 ----------------------------------------- (1)
Rn =AES (Ln f(Rn-l, Kn)) ------------------ (2)
Fig 1:(c) Hybrid AES DES flow structure
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From Equation (2), each Rn-1 and Kn is channeled into the
round function, which basically revolves on a XOR function
between these variables. The output of the round function is
then XORed with n- before being channeled as input data for
the AES algorithm. The result from the AES process
represents Rn. The AES operations include the byte
substitution, shift row, mix columns and add round key
operations.
Equations (1) and (2) are then iterated over a period of rounds,
retrospective to the number of keys as generated from the key
schedule process. The key schedule process for the hybrid
system is directly adapted from the AES standard and the
round keys for the AES process are directly adapted from the
expanded keys. The scheme of using a common set of keys
for the round functions within the Feistel network and the
AES functions as called during the operation reduces the
computational complexity in creating multiple sets of keys for
each overall hybrid operation. However, the mathematical
modeling for the key expansion of the AES limits its
generation at 10 keys based
on the number or rounds as applied for a 128 bit based AES
encryption process. Hence, the proposed number of iterations
for the hybrid system is set at 10. Nonetheless, the iterations
also vary based on the level of security implementation for the
Hybrid AES-DES. Note as seen from Equation (2), with every
round of iteration, the AES function is performed with
different sets of generated results based on varying sets of
expanded keys.
Fig 3: Detailed flow of Hybrid model
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As shown in the figure, we use AES within the Feistal
network and while doing so, increase the complexity of the
algorithm. This helps in securing the data in an enhanced way.
4. Result
Fig. 4.1: DES output
Fig. 4.2: AES output
Fig. 4.3: Hybrid Model output
Table 1: Comparison of encryption time
Encryption technique Encryption time(secs)
DES 0.15581
AES 1.85287
Hybrid AES DES 16.4857
5. CONCLUSION
Thus the paper uses combined concept of AES and DES to
obtain a hybrid model which can be used for encrypting
various kinds of data.
Nowadays it is very important to design strong encryption
algorithms as the power of computers is growing day by day.
Thus the hybrid model gives a better non linearity to the plain
AES and as it is merged with DES, there is better diffusion.
Hence the possibility of an algebraic attack on the hybrid
model is reduced.
From the table 1, we can see that the encryption time for the
hybrid model is much greater than the times for AES and
DES. Thus it can be inferred that the hybrid model will take
longer time to be broken by cryptanalysis
.
6. FURTHER ENHANCEMENTS
Being a hybrid of two powerful encryption standards the
algorithm will act as efficient and reliable encryption
technique for data. This hybrid model also is free of algebraic
attacks where AES fails as it is more prone to algebraic
attacks. The paper gives the performance criteria between
three algorithm techniques i.e. DES, AES and HYBRID AES-
DES. This makes it easy to compare the efficiency of all the
three techniques clearly with respect to time.
We can design a modified AES and/or DES so that we could
make the hybrid model even better compared to the present
system. The proposed algorithm can also use a double key
approach using chaos concept which makes it resistant to
linear attacks. In this case, the safety of encryption algorithm
can be further improved.
6. International Conference & Workshop on Recent Trends in Technology, (TCET) 2012
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7. REFERENCES
[1] An Improved AES algorithm based on chaos Yuan Kun,
Zhang Han, Li Zhaohui
[2] An Overview of Cryptanalysis Research for the Advanced
Encryption Standard
[3] An Efficient MPEG Video Encryption Algorithm
[4] H. Nover, "Algebraic Cryptanalysis of AES: Overview",
University of Wisconsin, USA, 2005.
[5] S. Murphy, MJ.B Robshaw, "Essential Algebraic Structure
within the AES", Advances in Cryptology CRYPTO
2002, Vol. 2442 of Lecture Notes in Computer Science,
Springer-Verlag, August 2002
[6] N. Courtois, A. Klimov, 1. Patarin, A. Shamir, "Efficient
algorithm for solving overdefmed systems of muhivariate
polynomial equations", Proceedings for Eurocrypt 2000,
LNCS 1807, pp 392407, Springer-Verlag, 2000.
[7] MATLAB Description, Available:
http://www.mathworks.in/help/
[8] AES Description, Available:
http://people.eku.edu/styere/Encrypt/JS-AES.html
[9] DES Description, Available:
http://orlingrabbe.com/des.htm
[10] AES mix column
http://www.angelfire.com/biz7/atleast/mix_columns.pdf