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.
MEO is a powerful data encryption application to encrypt or decrypt files of any type, including Microsoft Word, email, and PDF documents. It can also create self-extracting encrypted files. This is handy for those who like to view their encrypted files without installing any other encryption software. Also, many downloads supply a checksum or hash value for you to verify the integrity of your download. Meo allows you to create and verify MD5 checksums, SHA-1 hashes, and Tiger Tree hashes.
NetCrack is cluster software developed to distribute a hashing algorithm's cracking process work using a brute force attack. Currently, it only supports the two most commonly used hashing algorithms: MD5 and SHA-1. Support is included for MySQL, safe mode, and others. It works like a client/server application, where the server is unique for each cluster network and its job is to distribute the cracking process work, coordinate the nodes, and prevent connections and data integrity errors.
tkpg is a program that provides a GUI front end to Philip Zimmermann's Pretty Good Privacy (PGP) public-key encryption system and also the GNU Privacy Guard (GnuPG/gpg) implementation. It utilizes the Clipboard Selection heavily to ease moving pgp-processed text both to and from any of your applications (such as mail reader, news reader, and editor). This removes the need to select the output text by hand or by typing in a filename, since it is usually placed in the Selection automatically for you.
PyCryptoPlus is a cryptographic module similar to PyCrypto, with which it shares the API. But PyCryptoPlus is written 100% in Python, so its primary interest is educational and scientific; if you want real speed, you're better checking out PyCrypto. It was not completely written from scratch, but integrates other cipher codes when available in Python and under appropriate licenses. It contains, among other things: Block cipher algorithms (Serpent, Blowfish, Twofish, DES, 3DES, AES, Rijndael, and PRESENT); modes of operation (CMAC, ECB, CBC, CTR, and XTS); paddings (bit padding, zeros, PKCS7, PKCS12, ISO 10126, and ANSI X.923); and one-way functions (MD5, SHA1/SHA2, Whirlpool, RipeMD, RadioGatun, HMAC, and PBKDF2).
John the Ripper is a fast password cracker, currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. It supports several crypt(3) password hash types commonly found on Unix systems, as well as Windows LM hashes. On top of this, lots of other hashes and ciphers are added in the community-enhanced version (-jumbo), and some are added in John the Ripper Pro.
strongSwan is a complete IPsec implementation for the Linux, Android, Maemo, FreeBSD, and Mac OS X operating systems. It interoperates with with most other IPsec-based VPN products via the IKEv2 or IKEv1 key exchange protocols. The focus of the strongSwan project is on strong authentication mechanisms using X.509 public key certificates and optional secure storage of private keys on smartcards through a standardized PKCS#11 interface. A rich choice of modular plugins adds additional features like Trusted Network Connect or advanced cryptographical algorithms.