Twofish is an AES candidate produced by Schneier, Kelsey, Whiting, Wagner, Hall, Ferguson first presented in [SKWWHF98]. It is included as a separate section in this document because OpenPGP & NAI have decided that Twofish is such a promising cipher that it should be added to PGP prior to the outcome of the AES process [Koc98], [Pri99a]. Twofish is an evolution of the cipher Blowfish. Most changes seem to have been made to meet the AES criteria.

This is a contentious and subjective issue. None of these algorithms has either been broken or had any serious doubts cast upon their strength. Some people don't trust 3DES because it is based upon DES, which is produced by the NSA. However, respected cryptographers hold 3DES in very high regard.

NOTE: These figures are not from the PGP implementation of the ciphers, but are indicative of the underlying cipher performance.

AES encryption is not the only encryption algorithm that provides strong encryption. There are other encryption algorithms that can be used to secure your data. However, AES encryption is the current federal standard, and likely to be the basis for future state and federal regulations. AES encryption is the only algorithm that has a federally supported certification process.