Checksum and Hash Generators – used for verifying that a given bitstream is identical to another

• Cksum (Unix command)
  http://www.freebsd.org/cgi/man.cgi?query=cksum
• md5deep
  http://md5deep.sourceforge.net/
• md5sum (Unix command)
  http://www.linuxmanpages.com/man1/md5sum.1.php
• md5summer
  http://www.md5summer.org/
• Sha1sum
  http://en.wikipedia.org/wiki/Sha1sum