Somitra Kumar Sanadhya Palash Sarkar Deterministic Constructions of 21-Step Collisions for the SHA-2 Hash Family. 244-259 2008 ISC http://dx.doi.org/10.1007/978-3-540-85886-7_17 conf/isw/2008 db/conf/isw/isc2008.html#SanadhyaS08