RC5
RC5 uses stream encryption. RC5 is used in the SSL protocol.
DES (Digital Encryption Standard)
DES uses block encryption and a 56-bit key. It was developed by IBM and the NSA (National Security Agency) of the USA in the late seventies. Electronic Frontier Foundation cracked the key and decrypted the text encrypted with DES in less than 24 hours in 1999.
Triple DES
Triple DES has replaced DES. It uses block encryption. The basic algorithmic principles have not changed, however in Triple DES data blocks are encrypted with three different keys. Thus, Triple DES uses a 168-bit key. Later, a vulnerability lessened the time required to crack a 168-bit key to the time required to crack a 108-bit key. Basically, a 108-bit key is sufficient for quite reliable encryption today. However, in the future, it will be insufficient. One more disadvantage of this algorithm is its low processing speed.
AES (Advanced Encryption Standard)
When NIST (National Institute of Standards and Technology) announced the developers contest for a new encryption algorithm, one of the main terms was that developers must relinquish any intellectual property. This has allowed the new standard to be free. All "candidates" (algorithms) were extensively examined by the world community and on October 2nd, 2000, NIST announced the winners. They were two Belgian cryptographers: Joan Daemen and Vincent Rijmen. Since that time AES has become a world cryptographic standard and is now supported by almost all security applications.
Blowfish
Blowfish uses block encryption with a 64-bit key of variable length. The algorithm has two stages: key expansion and data encryption itself. Key expansion transforms a key into a 448-bit key. Data encryption is based on a sixteen iteration Feistel network. One of the main benefits of this algorithm is speed: most of the time is spent on key expansion which is performed only once.
FastTrackFTP supports DES, TripleDES, Blowfish, Twofish256, Twofish192, Twofish128, AES256, AES192, AES128, Serpent256, Serpent192, Serpent128, ARCFOUR, IDEA, and CAST128.