cfv is a utility to both test and create .sfv (Simple File Verify), .csv, .crc, .md5(sfv style), md5sum, BSD md5, sha1sum, and .torrent checksum verification files. It also includes test-only support for .par and .par2 files. These files are commonly used to ensure the correct retrieval or storage of data.
The ECLiPt Mirroring Tool is a full featured FTP mirror script written in Python. It supports nice config files, many features for controlling the mirror (include, exclude of files, special watermarks for deleting files, download just the latest version of some program), as well as producing nice HTML output.
Pysync has both a demonstration implementation of the rsync and related algorithms in pure Python, and a high speed librsync Python extension. The pure Python is not fast and is not optimized, however it does work and provides a simple implementation of the algorithm for reference and experimentation. It includes a combination of ideas taken from librsync, xdelta, and rsync. The librsync Python extension is less flexible and harder to understand, but is very fast.
python-fchksum is a module used to find checksums of files (or stdin). It supports md5, crc32, cksum, bsd-style sum, and sysv-style sum. The advantage of using fchksum over the Python md5 and zlib(.crc32) modules is both ease of use and speed. You only need to tell it the filename, and the work is done by C code.
Python-LZO provides Python bindings for the LZO data compression library. You can access the LZO library from your Python scripts thereby compressing ordinary Python strings. LZO is a portable lossless data compression library written in ANSI C. It offers pretty fast compression and *very* fast decompression. Decompression requires no memory. In addition there are slower compression levels achieving a quite competitive compression ratio while still decompressing at this very high speed.
Xfiles is an interactive utility for comparing and merging one file tree with another over a network. It supports freeform work on several machines (no need to keep track of what files are changed on which machine). Xfiles can also be used as a cross-validating disk<->disk backup strategy.
GNotary is a set of Python scripts that implement an asynchronous digital notary service. Anybody who needs certification of any digital document creates a message digest (like MD5 or RIPEMD160) of that document and submits it to the GNotary service by email. GNotary signs this email digitally (using GnuPG), retains a copy of the certified and time stamped message, and mails it back to the sender, optionally with the public key attached to allow the sender to verify the signed document. At regular intervals, the GNotary server creates message digests of its own logs and distributes them among other GNotary servers, thus making it virtually impossible to forge the chain of evidence that authenticates a submitted document.