Second-Order Differential Collisions for Reduced SHA-256 [chapter]

Alex Biryukov, Mario Lamberger, Florian Mendel, Ivica Nikolić
<span title="">2011</span> <i title="Springer Berlin Heidelberg"> <a target="_blank" rel="noopener" href="" style="color: black;">Lecture Notes in Computer Science</a> </i> &nbsp;
In this work, we introduce a new non-random property for hash/compression functions using the theory of higher order differentials. Based on this, we show a second-order differential collision for the compression function of SHA-256 reduced to 47 out of 64 steps with practical complexity. We have implemented the attack and provide an example. Our results suggest that the security margin of SHA-256 is much lower than the security margin of most of the SHA-3 finalists in this setting. The
more &raquo; ... es employed in this attack are based on a rectangle/boomerang approach and cover advanced search algorithms for good characteristics and message modification techniques. Our analysis also exposes flaws in all of the previously published related-key rectangle attacks on the SHACAL-2 block cipher, which is based on SHA-256. We provide valid rectangles for 48 steps of SHACAL-2.
<span class="external-identifiers"> <a target="_blank" rel="external noopener noreferrer" href="">doi:10.1007/978-3-642-25385-0_15</a> <a target="_blank" rel="external noopener" href="">fatcat:p4det7oor5h5rntocdrstjvmjy</a> </span>
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