"The MD5 checksum algorithm implements a one-way hash function. While it is widely used, many weaknesses are known and it should not be used in new applications (" { $url "http://www.schneier.com/blog/archives/2005/03/more_hash_funct.html" } ")."
"The SHA1 checksum algorithm implements a one-way hash function. It is generally considered to be stronger than MD5, however there is a known algorithm for finding collisions more effectively than a brute-force search (" { $url "http://www.schneier.com/blog/archives/2005/02/sha1_broken.html" } ")."