Abstract: Many papers deal with the problem of constructing an efficient masking scheme for existing block ciphers. We take the reverse approach: that is, given a proven masking scheme (Rivain and Prouff, CHES 2010) we design a block cipher that fits well the masking constraints. The difficulty of implementing efficient masking for a block cipher comes mainly from the S-boxes. Therefore the choice of an adequate S-box is the first and most critical step of our work. The S-box we selected is non-bijective; we discuss the resulting design and security problems. A complete design of the cipher is given, as well as some implementation results.

Abstract: Cryptography is the study of mathematical techniques related to aspects of information security such as confidentiality, data integrity, entity authentication and data origin authentication. In data and telecommunications, cryptography is necessary when communicating over any unreliable medium, which includes any network particularly the internet. In this paper, a 128 bit AES encryption and Decryption by using Rijndael algorithm (Advanced Encryption Standard algorithm) is been made into a synthesizable using Verilog code which can be easily implemented on to FPGA. The algorithm is composed of three main parts: cipher, inverse cipher and Key Expansion. Cipher converts data to an unintelligible form called plaintext. Key Expansion generates a Key schedule that is used in cipher and inverse cipher procedure. Cipher and inverse cipher are composed of special number of rounds. For the AES algorithm, the number of rounds to be performed during the execution of the algorithm uses a round function that is composed of four different byte-oriented transformations: Sub Bytes, Shift Rows, Mix columns and Add Round Key. Index Terms—Advanced Encryption Standard, Cryptography, Decryption, Encryption.

Abstract: Since the introduction of the Data Encryption Standard (DES) in the mid-1970s, block cipher is a wildly used algorithm in modern society. Along with the deep cryptanalysis, drawbacks of block cipher such as DES have been found which means improvement of cryptology should be done to face the challenge. Some block cipher algorithms such as SM4 are proposed to strong security. This paper describes the basic block cipher algorithm, design theory and structure, and cryptanalysis according to recent trend of development.

Abstract: Cryptography is an art and science of converting original message into nonreadable form.There are two techniques for converting data into nonreadable form:1)Transposition technique 2)Substitution technique.Caesar cipher is an example of substitution method.As Caesar cipher has various limitations so this talk will present a perspective on combination of techniques substitution and transposition.A double columnar transposition method is applied on Caesar cipher in order to overcome all limitation of Caesar cipher and provide much more secure and strong cipher.

Abstract: The Vigenere Cipher is a traditional method which involves encrypting alphabetic text by using a series of different Caesar Ciphers based on the letters of a keyword. The Vigenere Cipher works on the set of 26 English alphabets. In this paper we introduce the Alpha-Qwerty Cipher and reverse Alpha-Qwerty Ciphers which are the extensions to the Vigenere Cipher. This cipher works on a set of 92 characters by introducing case sensitivity and by adding digits and some other symbols to the existing Vigenere Cipher which is of 26 characters. This paper also modifies the mapping sequence from the plain text to the cipher text.

Abstract: In recent years there is drastic progress in Internet world. Sensitive information can be shared through internet but this information sharing is susceptible to certain attacks. Cryptography was introduced to solve this problem. Cryptography is art for achieving security by encoding the plain text message to cipher text. Substitution and transposition are techniques for encoding. When Caesar cipher substitution and Rail fence transposition techniques are used individually, cipher text obtained is easy to crack. This talk will present a perspective on combination of techniques substitution and transposition. Combining Caesar cipher with Rail fence technique can eliminate their fundamental weakness and produce a cipher text that is hard to crack.

Abstract: This study aims to obtain the digital image encryption algorithm with a simple but secure process, fast and efficient computing resources. The algorithms developed in this study were super-encryption algorithm that combines two of cipher called Playfair cipher and the Vigenere cipher. To improve security, a keystream generator was used to randomize the order of the next key in Vigenere cipher. In order to evaluate performance, the proposed algorithm was measured through a series of tests. These tests were implemented with Matlab included visual test and histogram analysis, information entropy, encryption quality, correlation analysis, and also time analysis. The test results show that cipher image looks visually random.The image histogram of the plain image and cipher image also seen a significant difference between the two of them. Testing was also performed on mobile phones with Symbian and BADA operating system based on Java Micro Edition Programming. Trial results show that the algorithm was require less computational resources; with average time for image encryption is 3.76 seconds, and the average time for image decryption is 0.97 seconds. The new proposed image encryption scheme has satisfactory security which makes it a potential candidate for encryption of image data. Keywords : Image encryption, Vigenere cipher, Playfair cipher, Security test DOI: http://dx.doi.org/10.11591/telkomnika.v10i4.875

Abstract: The theme of this research is to provide security for the data that contains alphabets numerals and special characters during its transmission. However because of the drawbacks inherent in the classical Playfair cipher which adversely affects the security, this research proposed 3D-Playfair Cipher (4 X 4 X 4 Playfair cipher) which works on trigraph rather than using digraph which eliminates the fact that a diagram and its reverse will encrypt in a similar fashion. 3D-Playfair cipher supports all 26 alphabets {AZ}, 10 digits {0-9} and 28 special characters { ! “ # $ % & ‘ ( ) * + , - . / : ; ? @ [ \ ] ^ _ | } which eliminate the limitation of classical Playfair in which “i” and “j” both character cannot appear at the same time. 3D-Playfair enhances the security by increasing complexity. Various types of cryptography attacks have been taken under consideration for original Playfair cipher but not vulnerable for this proposed cipher.

Abstract: In this paper, we analyze a slide property of RAKAPOSHI stream cipher. To begin, we show that any Key-IV pair has a corresponding slide Key-IV pair that generates an n-bit shifted keystream with probability of 2− 2n . Then we exploit this property in order to develop a key recovery attack on RAKAPOSHI in the related key setting. Our attack is able to recover a 128-bit key with time complexity of 241 and 238 chosen IVs. The result reveals that RAKAPOSHI is vulnerable to the related key attack. After that, we consider a variant of the slide property, called partial slide property. It enables us to construct a method for speeding up the brute force attack by a factor of 2 in the single key setting. Finally, we consider a slide property of K2 v2.0 stream cipher, and discuss the possibility of an attack exploiting the slide property.

Abstract: In this paper, a new Chaotic Map with Block Chaining (CMBC) cryptosystem for image encryption is proposed. It is a simple block cipher based on logistic chaotic maps and cipher block chaining (CBC). The new system utilizes simplicity of implementation, high quality, and enhanced security by the combined properties of chaos and CBC cipher. Implementation of the proposed technique has been realized for experimental purposes, and tests have been carried out with detailed analysis, demonstrating its high security. Results confirm that the scheme is unbreakable with reference to many of the well-known attacks. Comparative study with other algorithms indicates the superiority of CMBC security with slight increase in encryption time.

Abstract: Both stream ciphers and block ciphers can be used to provide data confidentiality service. Stream ciphers are preferred in many applications, since they can destroy statistical properties of natural languages to some extent. However, it seems hard to design a stream cipher with many proven security properties. The objective of this paper is to present a binary stream cipher which is secure with respect to a number of attacks, and has reasonable performance. The advantage of the stream cipher over existing ones is that it has more proven security properties.

Abstract: The block cipher modes of operation that are widely used (CBC, CTR, CFB) are secure up to the birthday bound; that is, if w2 or fewer bits of data are encrypted with a w-bit block cipher. However, the detailed security properties close to this bound are not widely appreciated, despite the fact that 64-bit block ciphers are sometimes used in that domain. This work addresses the issue by analyzing plaintext-recovery attacks that are effective close to that bound. We describe possibleplaintext attacks, which can learn unknown plaintext values that are encrypted with CBC, CFB, or OFB. We also introduce impossible plaintext cryptanalysis, which can recover information encrypted with CTR, and can improve attacks against the aforementioned modes as well. These attacks work at the birthday bound, or even slightly below that bound, when the target plaintext values are encrypted under a succession of keys.

Abstract: In this paper, we have developed a novel block cipher, which involves a key bunch matrix in the process of encryption. In order to carry out the decryption process, we have obtained the multiplicative inverse of each key in the encryption key bunch matrix by using the concept of multiplicative inverse, and constructed the decryption matrix. In this analysis, the cryptanalysis clearly shows that the strength of the cipher is remarkable, and this cipher can be used for the transmission of information, like any other well-known cipher, through internet.

Abstract: In this paper we analyze the advantages and disadvantages of conventional block cipher and one-way hash algorithm, and given a one-time pad encryption algorithm based on them. This algorithm fully compensate for the inadequacies of the conventional block cipher, while use the advantages of the one-way hash algorithm. And it is a safe and simple algorithm. This algorithm can be easy used and expanded on the conventional block cipher.

Abstract: In this paper, we have developed a block cipher involving a key bunch matrix. In each round of the iteration process we have introduced a permutation process, wherein we have converted the plaintext matrix into binary bits, arranged in a row wise manner, and offered right rotation to the first row and downward rotation to the first column. Then on seeing the resulting matrix as a bunch of sub-matrices, we have swapped the sub-matrices. The cryptanalysis carried out in this investigation shows very clearly that this cipher cannot be broken by any attack.

Abstract: In Hill Cipher, the plain text is divided into equal sized blocks. The blocks are encrypted one at a time. Cipher text only Crypto analysis of Hill Cipher is difficult. But it is susceptible to known plain text attack. In this work, Hill Cipher is improvised to make it more secure. The output of hill cipher is randomized to generate multiple cipher texts for one plain text. Any one cipher text is used for transmission of data. This approach thwarts any known plain text attacks and also chosen cipher text attacks.

Abstract: In data encryption, the security of the algorithm is measured based on Shannon’s confusion and diffusion properties. This paper identifies the correspondences and highlights the essential computation elements on the basis of randomness and non-linearity of immune systems. These systems can be applied in symmetric encryption algorithm that satisfies the properties in designing a new symmetric encryption block cipher. The proposed symmetric encryption block cipher called the 3D-AES uses components of the Advanced Encryption Standard (AES) symmetric encryption block cipher and the new core components based on immune systems approaches. To ensure adequate high security of the systems in the world of information technology, the laboratory experiment results are presented and analyzed. They show that the randomness and non-linearity of the output in the 3D-AES symmetric encryption block cipher are comparable to the AES symmetric encryption block cipher.

Abstract: In this paper conventional Playfair Cipher is being modified by encrypting the plaintext in blocks. For each block the keyword would be the same but the matrix will shift by some random value. As a result of which the diagram analysis would be very difficult which is done in the traditional Playfair Cipher to obtain the plaintext from the ciphertext. The shift value will be generated using SHA-1 which is very secure. Playfair Cipher method, based on polyalphabetic cipher is relatively easy to break because it still leaves much of the structure and a few hundred of letters of ciphertext are sufficient. To add to its security and to make it more usable we are using 6x6 matrix instead of 5x5 which will be able to cover 26 alphabets in English and ten numerals i.e. from 0 to 9. This 6x6 matrix eliminate the case of putting of 2 alphabets (I and J) together in the matrix as it was in the 5x5 matrix. Plaintext as well as key can be numeral, alphabetic or combination of both.

Abstract: In this paper we study a 128-bit-key cipher called PC1 which is used as part of the DRM system of the Amazon Kindle e-book reader This is the first academic cryptanalysis of this cipher and it shows that PC1 is a very weak stream cipher, and can be practically broken in a known-plaintext and even in a ciphertext-only scenario

Abstract: The MISTY1 block cipher has a 64-bit block length, a 128-bit user key and a recommended number of 8 rounds. It is a Japanese CRYPTREC-recommended e-government cipher, an European NESSIE selected cipher, and an ISO international standard. Despite of considerable cryptanalytic efforts during the past fifteen years, there has been no published cryptanalytic attack on the full MISTY1 cipher algorithm. In this paper, we present related-key differential and related-key amplified boomerang attacks on the full MISTY1 under certain weak key assumptions: We describe 2 weak keys and a related-key differential attack on the full MISTY1 with a data complexity of 2 chosen ciphertexts and a time complexity of 2 encryptions; and we also describe 2 weak keys and a related-key amplified boomerang attack on the full MISTY1 with a data complexity of 2 chosen plaintexts and a time complexity of 2 encryptions. For the very first time, our results exhibit a cryptographic weakness in the full MISTY1 cipher (when used with the recommended 8 rounds), and show that the MISTY1 cipher is distinguishable from a random function and thus cannot be regarded to be an ideal cipher.

Abstract: Recently, several important block ciphers are considered to be broken by the bruteforce-like cryptanalysis, with a time complexity faster than exhaustive key search by going over the entire key space but performing less than a full encryption for each possible key. Motivated by this observation, we describe a meet-in-the-middle attack that can always be successfully mounted against any practical block ciphers with success probability one. The data complexity of this attack is the smallest according to the unicity distance. The time complexity can be written as 2(1 − ) where > 0 for all block ciphers. Previously, the security bound that is commonly accepted is the length k of the given master key. From our result we point out that actually this k-bit security is always overestimated and can never be reached due to the inevitable key bits loss. No amount of clever design can prevent it, but increments of the number of rounds can reduce this key loss as much as possible. We give more insight in the problem of the upper bound of effective key bits in block ciphers, and show a more accurate bound. A suggestion about the relation between the key size and block size is given. That is, when the number of rounds is fixed, it is better to take a key size equal to the block size. Moreover, effective key bits of many well-known block ciphers are calculated and analyzed, which also confirm their lower security margin than thought before.

Abstract: This paper presents BOKHARI; a new proposed software-oriented stream cipher constructed using a Non-linear feedback shift register and a Non linear filter function and is designed for a secret key that is up to 128 bits in length. The BOKHARI stream cipher uses both basic design principles from the stream cipher SOBER-U6 and transformations derived from the steam cipher DRAGON.

Abstract: In this paper, we have developed a modification to the Feistel cipher by taking the plaintext in the form of a pair of matrices and introducing a set of functions namely, substitute, shifting of rows, mixing of columns and XOR operation with a key. Further we have supplemented this process by using another function called shuffling at the end of each round of the iteration process. In this analysis, the cryptanalysis clearly indicates that the strength of the cipher is quite significant and this is achieved by the introduction of the aforementioned functions.

Abstract: In cryptography, encryption is the process of transforming information referred to as plaintext using an algorithm (called a cipher) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is information which is, referred to as ciphertext. Stream ciphers are used to encrypt individual bits. This is achieved by adding a bit from a key stream to a plaintext bit.Generating the key stream is the therefore important. In this paper a soft computing based approach is proposed for generating keys to design a stream cipher for text encryption. Optimal weights for the sender and receiver used for the synchronization on the Tree Parity Machine(TPM) neural network, are generated using a Genetic Algorithm(GA).