A facility for encrypting and decrypting small amounts of data with a symmetric key. This is most commonly used for encrypting password files to implement single sign-on.

KeyManager is used to create, lookup, and delete the symmetric keys used for SecretDecoderRing. Encryptor is used to encrypt data. Decryptor is used to decrypt data that was previously encrypted with Encryptor. Encoding and Encoding.Template are used internally, but they were made public because they may occasionally be useful to applications.