Computes the exclusive-or between a message and a cryptographic random
stream indexed by the
Key and the
Nonce. This renders
the output indistinguishable from random noise so long as the
Nonce is not used more than once.
Note: while this can
be used for encryption and decryption, it is
possible for an
attacker to manipulate the message in transit without
detection. USE AT YOUR OWN RISK.