/// <summary>
/// Diffie-Hellman (function computes a secret shared by the two keys)
/// </summary>
/// <param name="secretKey">A secret key.</param>
/// <param name="publicKey">A public key.</param>
/// <returns>A computed secret shared.</returns>
/// <exception cref="KeyOutOfRangeException"></exception>
public static byte[] Mult(byte[] secretKey, byte[] publicKey)
{
//validate the length of the scalar
if (secretKey == null || secretKey.Length != SCALAR_BYTES)
{
throw new KeyOutOfRangeException("secretKey", secretKey == null ? 0 : secretKey.Length,
string.Format("secretKey must be {0} bytes in length.", SCALAR_BYTES));
}
//validate the length of the group element
if (publicKey == null || publicKey.Length != BYTES)
{
throw new KeyOutOfRangeException("publicKey", publicKey == null ? 0 : publicKey.Length,
string.Format("publicKey must be {0} bytes in length.", BYTES));
}
var secretShared = new byte[BYTES];
SodiumLibrary.crypto_scalarmult(secretShared, secretKey, publicKey);
return(secretShared);
}
