MISTY and the Design Intent Behind it MISTY is the family name for two 64-bit blockcipher algorithms, MISTY1 and MISTY2, that have 128-bit keys, designed by the corporation with detailed specifications announced in academic conferences in 1996 and 1997.[1] [2] In terms of security, MISTY has the major benefit of “provable security,” in which the security is proven mathematically against differe...

This paper revisits a public key cryptosystem which is based on finite Church-Rosser string-rewriting systems. We consider some ideas for cryptanalysis and discuss issues concerning practical usage. It turns out that without changing crucial details of key generation this cryptosystem does not offer acceptable cryptographic security. We also provide the source code of our rudimentary implementa...

We present a birthday attack against DES. It is entirely based on the relationship Li+1 = Ri and the simple key schedule in DES. It requires about 2 ciphertexts of the same R16, encrypted by the same key K. We conjecture it has a computational complexity of 2. Since the requirement for the birthday attack is more accessible than that for Differential cryptanalysis, Linear cryptanalysis or Davie...

Hypothesis tests have been used in the past as a tool in a cryptanalytic context. In this paper, we propose to use this paradigm and define a precise and sound statistical framework in order to optimally mix information on independent attacked subkey bits obtained from any kind of statistical cryptanalysis. In the context of linear cryptanalysis, we prove that the best mixing paradigm consists ...

Recently, various cryptanalysis methods related to Cube Attack have attracted a lot of interest. We designed a practical platform to perform such cryptanalysis attacks. We also developed a web-based application at http://cube-attack.appspot.com/, which is open to public for simple testing and verification. In this paper, we focus on linearity testing and try to verify the data provided in sever...

Matsui's linear cryptanalysis for iterated block ciphers is generalized by replacing his linear expressions with I/O sums. For a single round, an I/O sum is the XOR of a balanced binary-valued function of the round input and a balanced binary-valued function of the round output. The basic attack is described and conditions for it to be successful are given. A procedure for nding e ective I/O su...

Attacks on cryptographic systems are limited by the available computational resources. A theoretical understanding of these resource limitations is needed to evaluate the security of cryptographic primitives and procedures. This study uses an Attacker versus Environment game formalism based on computability logic to quantify Shannon’s work function and evaluate resource use in cryptanalysis. A ...

Bitwise-Xor of two 4 bit binary numbers or 4-bit bit patterns entitled 4-bit differences carries information in Cryptography. The Method to Analyze Cryptographic cipher algorithms or 4-bit substitution boxes with 4-bit differences is known as Differential Cryptanalysis. In this paper a brief review of Differential Cryptanalysis of 4-bit bijective Crypto S-Boxes and a new algorithm to analyze th...

We present a detailed security analysis of the CAESAR candidate Ascon. Amongst others, cube-like, differential and linear cryptanalysis are used to evaluate the security of Ascon. Our results are practical key-recovery attacks on round-reduced versions of Ascon-128, where the initialization is reduced to 5 out of 12 rounds. Theoretical keyrecovery attacks are possible for up to 6 rounds of init...

We introduce a new methodology for designing block ciphers with provable security against differential and linear cryptanalysis. It is based on three new principles: change of the location of round functions, round functions with recursive structure, and substitution boxes of different sizes. The first realizes parallel computation of the round functions without losing provable security, and th...