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.
Botan is a crypto library written in C++. It provides a variety of cryptographic algorithms, including common ones such as AES, MD5, SHA, HMAC, RSA, Diffie-Hellman, DSA, and ECDSA, as well as many others that are more obscure or specialized. It also offers SSL/TLS (client and server), X.509v3 certificates and CRLs, and PKCS #10 certificate requests. A message processing system that uses a filter/pipeline metaphor allows for many common cryptographic tasks to be completed with just a few lines of code. Assembly and SIMD optimizations for common CPUs offers speedups for critical algorithms like AES and SHA-1.
Bitcoin is a peer-to-peer electronic cash system that is completely decentralized, without the need for a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of a P2P network to check for double-spending.
XCA is an interface for managing RSA and DSA keys, certificates, certificate signing requests, revocation lists and templates. It uses the OpenSSL and Qt4 libraries. Certificates and requests can be created and signed and many x509v3 extensions can be added. XCA supports multiple root and intermediate Certificate authorities. The CAs can be used to create CRLs and extend certificates. The following file-formats are supported: PEM, DER, PKCS#7, PKCS#8, PKCS#10, PKCS#12, and SPKAC.
Enigmail is an extension for the mail client of Mozilla, Netscape 7.x, and Mozilla Thunderbird that allows users to access the authentication and encryption features provided by the popular GnuPG software. It can encrypt/sign mail when sending, decrypt/authenticate received mail, and import/export public keys. It supports both the inline PGP format and the PGP/MIME format, which can be used to encrypt attachments, and is cross-platform, although binaries are supplied only for a limited number of platforms. Enigmail uses inter-process communication to execute GPG to carry out encryption/authentication.
SaluSafe is an encrypted email, chat, and file storage and sharing system. Your email and files are highly encrypted end-to-end, and cannot be intercepted by any third party. It was built from the ground up for security via strong cryptography, and is not just another security wrapper on top of an existing email solution.
Open Transactions is a solid, easy-to-use, financial crypto and digital cash library, including an API, server, and test client. It features anonymous numbered accounts, untraceable digital cash, triple-signed receipts, basket currencies, and signed XML contracts. It also supports cheques, invoices, payment plans, markets with trades, and other instruments. It uses OpenSSL and Lucre blinded tokens.
TaoCrypt is a portable, fast, cryptographic library for most needs. Its features include one way hash functions: SHA-1, MD2, MD4, MD5, RIPEMD-160; message authentication codes: HMAC; block ciphers: DES, Triple-DES, AES, Blowfish, Twofish; stream ciphers: ARC4; public key cryptography: RSA, DSA, Diffie-Hellman; password based key derivation: PBKDF2 from PKCS #5; a pseudo random number generator and large integer support. There is also support for Base 16/64 encoding/decoding, DER encoding/decoding, and X.509 processing.