crypto.createDiffieHellman(prime[, prime_encoding][, generator][, generator_encoding])
Creates a DiffieHellman key exchange object using the supplied prime and an optional specific generator.
The generator argument can be a number, string, or Buffer. If generator is not specified, the value 2 is used.
The prime_encoding and generator_encoding arguments can be 'binary', 'hex', or 'base64'.
If prime_encoding is specified, prime is expected to be a string; otherwise a Buffer is expected.
If ge