public enum EncryptionAlgorithm
|0||The AES 128-bit encryption algorithm.|
|1||The AES 192-bit encryption algorithm.|
|2||The AES 256-bit encryption algorithm.|
|3||The Camellia 128-bit encryption algorithm.|
|4||The Camellia 192-bit encryption algorithm.|
|5||The Camellia 256-bit encryption algorithm.|
|6||The Cast-5 128-bit encryption algorithm.|
|7||The DES 56-bit encryption algorithm.|
|8||The Triple-DES encryption algorithm.|
|9||The IDEA 128-bit encryption algorithm.|
|10||The Blowfish encryption algorithm.|
|11||The Twofish encryption algorithm.|
|12||The RC2 40-bit encryption algorithm (S/MIME only).|
|13||The RC2 64-bit encryption algorithm (S/MIME only).|
|14||The RC2 128-bit encryption algorithm (S/MIME only).|
|15||The SEED 128-bit encryption algorithm (S/MIME only).|
Represents the available encryption algorithms for use with S/MIME and OpenPGP.
RC-2/40 was required by all S/MIME v2 implementations. However, since the mid-to-late 1990's, RC-2/40 has been considered to be extremely weak and starting with S/MIME v3.0 (published in 1999), all S/MIME implementations are required to implement support for Triple-DES (aka 3DES) and should no longer encrypt using RC-2/40 unless explicitly requested to do so by the user.
These days, most S/MIME implementations support the AES-128 and AES-256 algorithms which are the recommended algorithms specified in S/MIME v3.2 and should be preferred over the use of Triple-DES unless the client capabilities of one or more of the recipients is unknown (or only supports Triple-DES).