This is md4sum, an MD4 message digests generator/checker based on the reference implementation published by R. Rivest, MIT Laboratory for Computer Science and RSA Data Security, Inc. with RFC1320 in April 1992. See RFC1186 and its update RFC1320 for algorithm. The usage is: md4sum [options] [file(s)]... see the manual page for more information. Md4sum should be available at the metalab ftp site at ftp://ibiblio.org/pub/Linux/utils/file/. See also: TP Müller's ed2k_hash program, http://sourceforge.net/projects/ed2k-tools/ (formerly at http://users.aber.ac.uk/tpm01/ed2k_tools/ed2k_hash.html).