class GPGME::Ctx

def encrypt(recp, plain, cipher = Data.new, flags = 0)

return the ciphertext.
Encrypt the plaintext in the data object for the recipients and 
def encrypt(recp, plain, cipher = Data.new, flags = 0)
  err = GPGME::gpgme_op_encrypt(self, recp, flags, plain, cipher)
  exc = GPGME::error_to_exception(err)
  raise exc if exc
  cipher
end