MD6

MD6 is a cryptographic hash function, formally the MD6 Message-Digest Algorithm, designed by Ronald Rivest together with a team of co-designers and published in 2008. It uses a structure resembling a Merkle tree, which lets very long inputs be hashed with a high degree of parallel computation; its authors claimed 28 cycles per byte for MD6-256 on an Intel Core 2 Duo and provable resistance to differential cryptanalysis, and speeds above 1 GB/s were reported on a 16-core processor. In December 2008 Douglas Held of Fortify Software found a buffer overflow in the reference implementation, which Rivest made public in February 2009 with a corrected release. MD6 was submitted to the NIST SHA-3 competition, but in July 2009 Rivest said it was not ready because of speed issues and a gap in the differential attack proof, and it did not advance to the second round. An improved proof was posted in September 2011.