**Data Encryption Standard (DES):**

Originally adopted by the U.S. government in 1977, the DES algorithm is still in use today. DES is a 56 bit key algorithm, but the key is too short to be used today for any serious security applications.

**Triple DES (3DES):**

This algorithm is an extension of the DES algorithm, which is three timres more powerful that the DES algorithm. The algorithm uses a 168 bit key.

**Blowfish:**

Blowfish is an algorithm that was designed to be strong, fast, and simple in its design. The algorithm uses a 448 bit key and is optimized for use in today's 32 bit and 64 bit processors. The algorithm was designed by encryption expert Bruce Schneier.

**International Data Encryption Algorithm (IDEA):**

Designed in switzerland and made available in 1990, this algorithm is seen in applications such as the Pretty Good Privacy (PGP) system.

**MARS:**

This AES finalist was developed by IBM and supports key lengths of 128-256 bits.

The AES competition was organized by the National Institute of Standards and Technology (NIST)

**RC2:**

Originally an algorithm that was a trade secret of RSA Labs, the RC2 algorithm crept into the public space in 1996. The algorithm allows keys between 1 and 2048 bits. The RC2 key length was traditionally limited to 40 bits in software that was exported to allow for decryption by the U.S. National Security Agency (NSA).

**RC4:**

Another algorithm that was originally a trade secret of RSA Labs, RC4 was revealed to the public via a newsgroup posting in 1994. The algorithm allows keys between 1 and 2048 bits.

**RC5:**

Similar to RC2 and RC4, RC5 allows users to define a key length.

**RC6:**

RC6 is another AES finalist developed by RSA Labs and supports key lengths of 128 to 256 bits.

**Rijndael:**

The cipher chosen for the Advanced Encryption Standard (AES). The successor to DES and chosen by NIST to be the new U.S. encryption standard. The algorithm is very compact and fast and can use keys that are 128, 192, or 256 bits long.

**Serpent:**

This AES finalist, developed by Ross Anderson, Eli Biham, and Lars Knudsen, supports key lengths of 128 to 256 bits.

**Twofish:**

This AES candidate, also developed by Bruce Schneier, supports key lengths of 12 to 256 bits.