The ciphers in GNU Crypto can usually be initiallized directly through
their constructors, but the preferred way is to use the
CipherFactory class, with the following method:
null if no such cipher exists. This method will throw a
java.lang.InternalError if the new instance's self-test fails.
The class also defines this method:
java.util.Set of the names (each element of
type java.lang.String) of all supported ciphers.