Summain
Summain is a command line application to compute checksums for files and to check files against pre-computed checksums. It can be used to check that files haven't been changed since the checksum was computed, e.g., that files burned on a CD or DVD haven't been corrupted while the disk was in storage.
A checksum is a number that identifies the contents of a file: if the contents change, so does the checksum. If you create a checksum before you burn a CD, when you know the files are correct, you can easily check the CD at any time: just compute the checksum again and see if they have changed.
Summain computes and checks files against such checksums. It supports both MD5 and SHA-1 checksums, using formats compatible with the md5sum and sha1sum utilities, both for reading and writing. In addition, it can read and verify checksums from Debian .dsc, .changes, and Sources files.
Summain is written in Python.
Current version is 1.0, released 2006-01-07.