What’s the Real Impact of SHA-256?

There are a variety of algorithms that can be used for generating checksums, with two in particular – MD5 and SHA-256 – being the most common. The comparative benefits and drawbacks of both are well-understood: while MD5 is weaker against random and deliberate collisions, it is faster to generate than SHA-256. However, there are no published empirical estimates for the difference in time-to-generate between MD5 and SHA-256 in archival and repository environments, leading to difficulty in making an informed decision as to which algorithm to implement for preservation monitoring. This white paper documents a comparative checksum test of the same files under the same conditions, leading to some surprising findings about the actual processing speeds of the two algorithms.