mcrypt is a program for encrypting files or streams. It is intended to be a replacement for the old UNIX crypt. It uses well-known and well-tested algorithms like BLOWFISH, AES, ARCFOUR, CAST-128, and more in several modes of operation. It also has a compatibility mode with the old UNIX crypt program and the des program found in Solaris.
shash is a program which produces message digests for files, and checks whether the digest remains the same (i.e., whether the files changed). Since anyone can generate the message digest, it may not be suitable for some security-related applications. Because of this, shash also supports HMAC (rfc2104), which is a mechanism for message authentication using cryptographic hash functions. shash can use a key with a hash algorithm to produce hashes that can only be verified with the same key. This way, you can securely check whether files in a filesystem were altered.
rsynchelper helps you use the mirroring program rsync. rsynchelper makes it easier for groups of servers to cooperate in mirroring. rsynchelper makes it easier to make your content available for others to mirror, makes it easier to mirror someone else's content, and it automates the maintenance of an accurate list of who is maintaining which content.
The RAZip bitstream format was designed to provide a faster random access to compressed data than what is currently possible using the GZIP format. Its major features include fast random access to compressed data, freedom from patents, single-pass coding/decoding using a bounded amount of intermediate storage, the ability to choose from one of many algorithms for compression, encryption, or error correction, and comprehensive support for Unix file metadata, Macintosh file metadata, and arbitrary file metadata.
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.
The GNotary client is a multi-platform GUI client that allows you to select files via drag and drop from any file manager, create the secure hash sums for each file, and submit the hash list to a list of digital notary servers. Optionally, all selected files can be backed up into a zip archive. It is written in Python and requires the wxPython toolkit.
Dar is a shell command that makes backup of a directory tree and files. Its features include splitting archives over several files, DVD, CD, ZIP, or floppies, compression, full or differential backups, strong encryption, proper saving and restoration of hard links, extended attributes, file forks, Door inodes, and sparse files, remote backup using pipes and external commands (such as ssh), and rearrangement of the "slices" of an existing archive. It can run commands between slices, before and after saving some defined files or directories (for a proper database backup, for example), and quickly retrieve individual files from differential and full backups. Several external GUIs exist as alternatives to its CLI interface, like kdar, DarGUI, SaraB, etc.