DHCrypt(BigInteger modulus,BigInteger base,SecureRandom random){
  this(modulus.bitLength(),new DHParameterSpec(modulus,base),random);
}

DHCrypt ( BigInteger modulus , BigInteger base , SecureRandom random ) { this ( modulus . bitLength ( ) , new DHParameterSpec ( modulus , base ) , random ) ; }
generate a diffie - hellman keypair using the specified parameters .
