Public-Key Cryptography is used for strong authentication, but X.509 is not dependent on the use of a particular cryptographic Algorithm, though two users wishing to authenticate must support the same Algorithm.

• 强认证使用公钥加密方式，但是X.；509并不依赖于使用特殊加密算法，尽管两个用户希望认证必须支持同一算法。