Collision attack

About: Collision attack is a research topic. Over the lifetime, 1093 publications have been published within this topic receiving 28389 citations.

On a Probabilistic Approach to the Security Analysis of Cryptographic Hash Functions.

Abstract: In this paper we focus on the three basic security requirements for a cryptographic hash function, commonly referred as preimage, second preimage and collision resistance. We examine these security requirements in the case of attacks which do not take advantage on how the hash function is computed, expressing them as success probabilities of suitable randomized algorithms. We give exact mathematical expressions for such resistance indices, and obtain their functional behaviour in relation to the amount of uniformity in the hash function outcomes. Our work provides a mathematical framework for the study of cryptographic hash functions, which enable us to give proofs for some prevailing beliefs.

Cryptanalysis of Dedicated Cryptographic Hash Functions

Abstract: In this thesis we study the security of a number of dedicated cryptographic hash functions against cryptanalytic attacks. We begin with an introduction to what cryptographic hash functions are and what they are used for. This is followed by strict definitions of the security properties often required from cryptographic hash functions. FSB hashes are a class of hash functions derived from a coding theory problem. We attack FSB by modeling the compression function of the hash by a matrix in GF(2). We show that collisions and preimages can easily be found in FSB with the proposed security parameters. We describe a meet-in-the-middle attack against the FORK-256 hash function. The attack requires 2112.8 operations to find a collision, which is a 38000-fold improvement over the expected 2128 operations. We then present a method for finding slid pairs for the compression function of SHA-1; pairs of inputs and messages that produce closely related outputs in the compression function. We also cryptanalyse two block ciphers based on the compression function of MD5, MDC-MD5 and the Kaliski-Robshaw “Crab” encryption algorithm. VSH is a hash function based on problems in number theory that are believed to be hard. The original proposal only claims collision resistance; we demonstrate that VSH does not meet the other hash function requirements of preimage resistance, one-wayness, and collision resistance of truncated variants. To explore more general cryptanalytic attacks, we discuss the d-Monomial test, a statistical test that has been found to be effective in distinguishing iterated Boolean circuits from real random functions. The test is applied to the SHA and MD5 hash functions.

Complexity Estimates of a SHA-1 Near-Collision Attack for GPU and FPGA

Abstract: The complexity estimate of a hash collision algorithm is given by the unit hash compressions. This paper shows that this figure can lead to false runtime estimates when accelerating the algorithm by the use of graphics processing units (GPU) and field-programmable gate arrays (FPGA). For demonstration, parts of the CPU reference implementation of Marc Stevens' SHA-1 Near-Collision Attack are implemented on these two accelerators by taking advantage of their specific architectures. The implementation, runtime behavior and performance of these ported algorithms are discussed, and in conclusion, it is shown that the acceleration results in different complexity estimates for each type of coprocessor.

Collision attack on XTR and a countermeasure with a fixed pattern

Abstract: Recently, XTR is considered as one of good candidates for more energy efficient cryptosystems. Among the family of XTR algorithms, the Improved XTR Single Exponentiation (XTR-ISE) is the most efficient one suitable for ubiquitous computer. Even though the security of such devices against side channel attacks is very dangerous, there are few works on side channel attacks against XTR-ISE. In this paper we propose a new collision attack on XTR-ISE. The analysis complexity of the proposed one is about 240 where the key size is 160-bit, which is 55% improvement from the previously best known analysis of Page-Stam. We also propose a novel countermeasure using a fixed pattern which is secure against SPA. In the sense of both efficiency and security the proposed countermeasure is the best one among the previous countermeasures- it is about 30% faster.

Method for constructing reinforced hash function based on compression function

Abstract: The invention belongs to the field of information safety, in particular to the cryptology field, and relates to a method for reinforcing a hash function based on a compression function. The method is used for reinforcing key loops of the hash function, namely reinforcing a first group of the compression function and a final group of the compression function, and increasing the operations of multiple bits or utilizing a present safety group code algorithm by aiming at a majority of operations of a present hash function based on a single bit. The method comprises the following steps of: reinforcing by taking a method of resisting a current differential code analysis and the like as the principal method, also considering about some other attacks, such as a second preimage attack, further adding an input variable in the input of the final group of the compression function, namely a simple compression manner of all group information. The reinforcing method disclosed by the invention has the advantages that when key groups are reinforced, the increase of calculated amount is not large along with the increase of the length of a plaintext; and the decoding obstacle is configured through the most key position, the preimage attack, collision attack, the second preimage attack and the like can be effectively resisted.