ECRecover contract upgrade

[YakupIpek]

The stratisproject/StratisBitcoinFullNode#4194 moved here.

This pr needs to have package from stratisproject/Stratis.SmartContracts#13

This pr has been reviewed actually and should to be complete but it was require to have hard-fork because upgrade needed on Stratis.SmartContracts assemblies.

Basically EcRecoverProvider.SignMessage(privateKey, message) returns a signature that we can recover PubKey address and we can do this via ECRecoverProvider.GetSigner(message, offChainSignature) in the smart contract code.

I reviewed&tested it and i don't have anything to add.

I am going to remove dev prefix from version(2.0.1-dev) if it is approved.

[quantumagi]

LGTM. Can merge when CI passes.

[rowandh]

I think this needs to be resolved before this can be used in production.

[YakupIpek]

@rowandh PubKey.RecoverCompact already detects incorrect format and raise an exception.

There is something else to do in here ?

[quantumagi]

Perhaps include support for VerifySignatures into this PR. See https://github.com/stratisproject/Stratis.SmartContracts/blob/1d30c10805b7b2b4c77440068642614394c54b28/Stratis.SmartContracts/IEcRecoverProvider.cs.

        private byte[][] DeserializeSignatures(byte[] signatures)
        {
            const int signatureLength = 65;
            const int minHeaderByte = 27;
            const int maxHeaderByte = 34;
            int cnt = signatures.Length / signatureLength;
            Guard.Assert(signatures.Length == signatureLength * cnt);
            var buffer = new byte[cnt][];
            for (int i = 0; i < cnt; i++)
            {
                Array.Copy(signatures, i * signatureLength, buffer[i], 0, signatureLength);
                Guard.Assert(buffer[i][0] >= minHeaderByte && buffer[i][0] <= maxHeaderByte);
            }
            return buffer;
        }

        /// <summary>
        /// Takes a message and signatures and returns the list of addresses that produced the signatures.
        /// </summary>
        /// <param name="message">The message that was signed.</param>
        /// <param name="signatures">The list of signatures of the message.</param>
        /// <param name="addresses">If not <c>null</c> the addresses returned are intersected with these addresses.</param>
        /// <returns>The list of addresses that produced the signatures and constrained to the list provided in <paramref name="addresses"/> if not <c>null</c>.</returns>
        public Address[] VerifySignatures(byte[] signatures, byte[] message, Address[] addresses = null)
        {
            Guard.NotNull(message, nameof(message));
            Guard.NotNull(signatures, nameof(signatures));
            var keyIds = DeserializeSignatures(signatures)
                .Select(s => PubKey.RecoverFromMessage(message, Encoders.Base64.EncodeData(s)).Hash);
            if (addresses != null)
                keyIds = keyIds.Intersect(addresses.Select(a => new KeyId(a.ToBytes())));
            return keyIds.Select(s => s.ToBytes().ToAddress()).ToArray();
        }

[quantumagi]

Perhaps this conversion can be done without using this.network.

[YakupIpek]

Fixed