We study the security of step-reduced but otherwise unmodified SHA-256. We show the first collision attacks on SHA-256 reduced to 23 and 24 steps with complexities 218 and 228.5, respectively. We give example colliding message pairs for 23-step and 24-step SHA-256. The best previous, recently obtained result was a collision attack for up to 22 steps. We extend our attacks to 23 and 24-step reduced SHA-512 with respective complexities of 244.9 and 253.0. Additionally, we show non-random behaviour of the SHA-256 compression function in the form of free-start near-collisions for up to 31 steps, which is 6 more steps than the recently obtained non-random behaviour in the form of a semi-free-start near-collision. Even though this represents a step forwards in terms of cryptanalytic techniques, the results do not threaten the security of applications using SHA-256. © 2009 Springer.
CITATION STYLE
Indesteege, S., Mendel, F., Preneel, B., & Rechberger, C. (2008). Collisions and other non-random properties for step-reduced SHA-256. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 5381 LNCS, pp. 276–293). https://doi.org/10.1007/978-3-642-04159-4_18
Mendeley helps you to discover research relevant for your work.