Generic message digest-based PRNGs are implemented via the
MDGenerator class, which defines the following additional
constants:
MDGenerator. The value mapped must be a String
representing the name of the hash function to use, such as
"MD5". If this attribute is omitted the secure hash algorithm,
SHA-1, is used.
MDGenerator. The value mapped must be a byte array carrying the
seed, with which to seed the PRNG. This attribute is optional.