A method for finding codewords of small weight
Proceedings of the 3rd International Colloquium on Coding Theory and Applications
Differential Collisions in SHA-0
CRYPTO '98 Proceedings of the 18th Annual International Cryptology Conference on Advances in Cryptology
New local collisions for the SHA-2 hash family
ICISC'07 Proceedings of the 10th international conference on Information security and cryptology
Analysis of step-reduced SHA-256
FSE'06 Proceedings of the 13th international conference on Fast Software Encryption
CT-RSA'05 Proceedings of the 2005 international conference on Topics in Cryptology
Finding collisions in the full SHA-1
CRYPTO'05 Proceedings of the 25th annual international conference on Advances in Cryptology
Cryptanalysis of the hash functions MD4 and RIPEMD
EUROCRYPT'05 Proceedings of the 24th annual international conference on Theory and Applications of Cryptographic Techniques
Exploiting coding theory for collision attacks on SHA-1
IMA'05 Proceedings of the 10th international conference on Cryptography and Coding
SAC'05 Proceedings of the 12th international conference on Selected Areas in Cryptography
IEEE Transactions on Information Theory
Non-linear Reduced Round Attacks against SHA-2 Hash Family
ACISP '08 Proceedings of the 13th Australasian conference on Information Security and Privacy
Deterministic Constructions of 21-Step Collisions for the SHA-2 Hash Family
ISC '08 Proceedings of the 11th international conference on Information Security
New Collision Attacks against Up to 24-Step SHA-2
INDOCRYPT '08 Proceedings of the 9th International Conference on Cryptology in India: Progress in Cryptology
A new hash family obtained by modifying the SHA-2 family
Proceedings of the 4th International Symposium on Information, Computer, and Communications Security
Finding SHA-2 characteristics: searching through a minefield of contradictions
ASIACRYPT'11 Proceedings of the 17th international conference on The Theory and Application of Cryptology and Information Security
Converting meet-in-the-middle preimage attack into pseudo collision attack: application to SHA-2
FSE'12 Proceedings of the 19th international conference on Fast Software Encryption
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The SHA-256 hash function has started getting attention recently by the cryptanalysis community due to the various weaknesses found in its predecessors such as MD4, MD5, SHA-0 and SHA-1. We make two contributions in this work. First we describe message modification techniques and use them to obtain an algorithm to generate message pairs which collide for the actual SHA-256 reduced to 18 steps. Our second contribution is to present differential paths for 19, 20, 21, 22 and 23 steps of SHA-256. We construct parity check equations in a novel way to find these characteristics. Further, the 19-step differential path presented here is constructed by using only 15 local collisions, as against the previously known 19-step near collision differential path which consists of interleaving of 23 local collisions. Our 19-step differential path can also be seen as a single local collision at the message word level. We use a linearized local collision in this work. These results do not cause any threat to the security of the SHA-256 hash function.