This module implements a chaining block cipher using a one
    way hash.  This method of encryption is the same that is
    used by radius (RFC2138) and is also described in Applied
    Cryptography.

    Two interfaces are provided in the module.  The first is
    straight block encryption/decryption the second does base64
    mime encoding/decoding of the encrypted/decrypted blocks.

    The idea is the the two sides have a shared secret that
    supplies one of the keys and a randomly generated block of
    bytes provides the second key.  The random key is passed in
    cleartext between the two sides.

    An example client and server are packaged as modules with
    this module.  They are used in the tests.