public ServerCommitment[] SignHashes(SignaturesRequest sigRequest)
{
if (sigRequest == null)
{
throw new ArgumentNullException(nameof(sigRequest));
}
if (sigRequest.Hashes.Length != Parameters.GetTotalTransactionsCount())
{
throw new ArgumentException("Incorrect number of hashes, expected " + sigRequest.Hashes.Length);
}
AssertState(PromiseServerStates.WaitingHashes);
List <ServerCommitment> promises = new List <ServerCommitment>();
List <EncryptedSignature> encryptedSignatures = new List <EncryptedSignature>();
foreach (var hash in sigRequest.Hashes)
{
var ecdsa = InternalState.EscrowKey.Sign(hash);
var ecdsaDER = ecdsa.ToDER();
var key = new XORKey(Parameters.ServerKey);
var promise = key.XOR(ecdsaDER);
PuzzleSolution solution = new PuzzleSolution(key.ToBytes());
var puzzle = Parameters.ServerKey.GeneratePuzzle(ref solution);
promises.Add(new ServerCommitment(puzzle.PuzzleValue, promise));
encryptedSignatures.Add(new EncryptedSignature(ecdsa, hash, solution));
}
InternalState.Status = PromiseServerStates.WaitingRevelation;
InternalState.EncryptedSignatures = encryptedSignatures.ToArray();
InternalState.FakeIndexesHash = sigRequest.FakeIndexesHash;
return(promises.ToArray());
}
public ServerCommitment[][] SignHashes(SignaturesRequest sigRequest)
{
// Almost done, just need to confirm a typo and a function.
// Step 5
if (sigRequest == null)
{
throw new ArgumentNullException(nameof(sigRequest));
}
var hashesCount = sigRequest.Hashes.Select(a => a.Length).Sum();
if (hashesCount != Parameters.GetTotalTransactionsCount())
{
throw new ArgumentException($"Incorrect number of hashes, expected {Parameters.GetTotalTransactionsCount()}");
}
AssertState(PromiseServerStates.WaitingHashes);
// 2D array of pairs of puzzles and promises (z_i, c_i).
var promises = new ServerCommitment[Parameters.PaymentsCount][];
// 2D array of encrypted signatures with their solutions.
var encryptedSignatures = new EncryptedSignature[Parameters.PaymentsCount][];
// 1-D array is used to store the epsilons for each column to be used when Hashing.
var previousSolutions = new byte[Parameters.GetTotalTransactionsCountPerLevel()][];
previousSolutions = previousSolutions.Select(a => new byte[0]).ToArray(); // Initialize to empty array of bytes
for (int i = 0; i < Parameters.PaymentsCount; i++)
{
promises[i] = new ServerCommitment[sigRequest.Hashes[i].Length]; // Initialization
encryptedSignatures[i] = new EncryptedSignature[promises[i].Length]; // Initialization
for (int j = 0; j < promises[i].Length; j++)
{
var hash = sigRequest.Hashes[i][j];
// Sign the hash value
var ecdsa = InternalState.EscrowKey.Sign(hash);
// Convert Signature to Bytes.
var ecdsaDER = ecdsa.ToDER();
// This can be replaced by "Utils.GenerateEncryptableInteger(Key)" if padding when XORing is not important.
var key = (new XORKey(Parameters.ServerKey)).ToBytes(); // This just generates a random epsilon.
// Append the new epsilon to the list of epsilons we have for that column to create "epsilon_{i-1,j}|| . . . , epsilon_{0,j}".
previousSolutions[j] = Utils.Combine(key, previousSolutions[j]);
// Create the padded solution with the following format "i||j||epsilon_{i,j}||epsilon_{i-1,j}|| . . . , epsilon_{0,j}"
var paddedSolutions = new PuzzleSolution(Utils.Combine(NBitcoin.Utils.ToBytes((uint)i, true), NBitcoin.Utils.ToBytes((uint)j, true), previousSolutions[j]));
// Hash and XOR the padded solution with the signature we have.
var promise = XORKey.XOR(paddedSolutions._Value.ToByteArrayUnsigned(), ecdsaDER); // This function needs to be approved "XOR".
PuzzleSolution solution = new PuzzleSolution(key); // Epsilon
// Encrypt the epsilon value using RSA
var puzzle = Parameters.ServerKey.GeneratePuzzle(ref solution);
promises[i][j] = new ServerCommitment(puzzle.PuzzleValue, promise);
encryptedSignatures[i][j] = new EncryptedSignature(ecdsa, hash, solution);
}
}
InternalState.Status = PromiseServerStates.WaitingRevelation;
InternalState.EncryptedSignatures = encryptedSignatures;
InternalState.FakeIndexesHash = sigRequest.FakeIndexesHash;
return(promises);
}
private bool IsValidSignature(PuzzleSolution solution, HashBase hash, out ECDSASignature signature)
{
signature = null;
var escrow = EscrowScriptPubKeyParameters.GetFromCoin(InternalState.EscrowedCoin);
try
{
var key = new XORKey(solution);
signature = new ECDSASignature(key.XOR(hash.Commitment.Promise));
var ok = escrow.Initiator.Verify(hash.GetHash(), signature);
if (!ok)
{
signature = null;
}
return(ok);
}
catch
{
}
return(false);
}
private bool IsValidSignature(PuzzleSolution solution, HashBase hash, out PubKey signer, out ECDSASignature signature)
{
signer = null;
signature = null;
try
{
var key = new XORKey(solution);
signature = new ECDSASignature(key.XOR(hash.Commitment.Promise));
foreach (var sig in GetExpectedSigners())
{
if (sig.Verify(hash.GetHash(), signature))
{
signer = sig;
return(true);
}
}
return(false);
}
catch
{
}
return(false);
}
