Ed25519.cs

using System;
using System.Security.Cryptography;
using Chaos.NaCl.Internal.Ed25519Ref10;

namespace Chaos.NaCl
{
    internal static class Ed25519
    {
        public static readonly int PublicKeySizeInBytes = 32;
        public static readonly int SignatureSizeInBytes = 64;
        public static readonly int ExpandedPrivateKeySizeInBytes = 32 * 2;
        public static readonly int PrivateKeySeedSizeInBytes = 32;
        public static readonly int SharedKeySizeInBytes = 32;

        public static void Sign(ArraySegment<byte> signature, ArraySegment<byte> message, ArraySegment<byte> expandedPrivateKey)
        {
            if (signature.Array == null)
                throw new ArgumentNullException("signature.Array");
            if (signature.Count != SignatureSizeInBytes)
                throw new ArgumentException("signature.Count");
            if (expandedPrivateKey.Array == null)
                throw new ArgumentNullException("expandedPrivateKey.Array");
            if (expandedPrivateKey.Count != ExpandedPrivateKeySizeInBytes)
                throw new ArgumentException("expandedPrivateKey.Count");
            if (message.Array == null)
                throw new ArgumentNullException("message.Array");
            Ed25519Operations.crypto_sign2(signature.Array, signature.Offset, message.Array, message.Offset, message.Count, expandedPrivateKey.Array, expandedPrivateKey.Offset);
        }

        public static byte[] Sign(byte[] message, byte[] expandedPrivateKey)
        {
            var signature = new byte[SignatureSizeInBytes];
            Sign(new ArraySegment<byte>(signature), new ArraySegment<byte>(message), new ArraySegment<byte>(expandedPrivateKey));
            return signature;
        }

        public static void KeyPairFromSeed(out byte[] publicKey, out byte[] expandedPrivateKey, byte[] privateKeySeed)
        {
            if (privateKeySeed == null)
                throw new ArgumentNullException("privateKeySeed");
            if (privateKeySeed.Length != PrivateKeySeedSizeInBytes)
                throw new ArgumentException("privateKeySeed");
            var pk = new byte[PublicKeySizeInBytes];
            var sk = new byte[ExpandedPrivateKeySizeInBytes];
            Ed25519Operations.crypto_sign_keypair(pk, 0, sk, 0, privateKeySeed, 0);
            publicKey = pk;
            expandedPrivateKey = sk;
        }
    }
}