'Encrypt a piece of data with ElGamal.
:Parameter plaintext: The piece of data to encrypt with ElGamal.
It must be numerically smaller than the module (*p*).
:Type plaintext: byte string or long
:Parameter K: A secret number, chosen randomly in the closed
range *[1,p-2]*.
:Type K: long (recommended) or byte string (not recommended)
:Return: A tuple with two items. Each item is of the same type as the
plaintext (string or long).
:attention: selection of *K* is crucial for security. Generating a
random number larger than *p-1* and taking the modulus by *p-1* is
**not** secure, since smaller values will occur more frequently.
Generating a random number systematically smaller than *p-1*
(e.g. *floor((p-1)/8)* random bytes) is also **not** secure.
In general, it shall not be possible for an attacker to know
the value of any bit of K.
:attention: The number *K* shall not be reused for any other
operation and shall be discarded immediately.'

def encrypt(self, plaintext, K):

    return pubkey.encrypt(self, plaintext, K)
