Blowfish is a symmetric block cipher with variable-length key (32 to 448 bits) designed in 1993 by Bruce Schneier as an unpatented, license-free, royalty-free replacement for DES or IDEA. See attributes below:
Block cipher: 64-bit block
Variable key length: 32 bits to 448 bits
Designed by Bruce Schneier
Much faster than DES and IDEA
Unpatented and royalty-free
No license required
Free source code available
Rivest Cipher #2 (RC2) is a proprietary, variable-key-length block cipher invented by Ron Rivest for RSA Data Security, Inc.
Rivest Cipher #4 (RC4) is a proprietary, variable-key-length stream cipher invented by Ron Rivest for RSA Data Security, Inc.
The Skipjack algorithm is a Type II block cipher [NIST] with a block size of 64 bits and a key size of 80 bits that was developed by NSA and formerly classified at the U.S. Department of Defense "Secret" level. The NSA announced on June 23, 1998, that Skipjack had been declassified.
References:
RSA Laboratories
http://www.rsa.com/rsalabs/node.asp?id=2250
RFC 2828 - Internet Security Glossary
http://www.faqs.org/rfcs/rfc2828.html
