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);
}
public ClientRevelation Reveal(ServerCommitment[][] commitments)
{
// Step 6
if (commitments == null)
{
throw new ArgumentNullException(nameof(commitments));
}
var CommitmentsCount = commitments.Select(a => a.Length).Sum(); // sums the number of commitments
var TransactionsCountPerLevel = Parameters.GetTotalTransactionsCountPerLevel();
if (CommitmentsCount != Parameters.GetTotalTransactionsCount())
{
throw new ArgumentException($"Expecting {Parameters.GetTotalTransactionsCount()} commitments");
}
AssertState(PromiseClientStates.WaitingCommitments);
uint256[][] salts = new uint256[_Parameters.PaymentsCount][];
Money[][] feeVariations = new Money[_Parameters.PaymentsCount][];
List <int> fakeIndices = new List <int>();
// This figures out the indices of fake hashes.
for (int i = 0; i < TransactionsCountPerLevel; i++)
{
if (_Hashes.First()[i] is FakeHash)
{
fakeIndices.Add(i);
}
}
for (int i = 0; i < _Parameters.PaymentsCount; i++)
{
salts[i] = new uint256[_Parameters.FakeTransactionCountPerLevel];
feeVariations[i] = new Money[_Parameters.RealTransactionCountPerLevel];
int fakeJ = 0, realJ = 0;
for (int j = 0; j < TransactionsCountPerLevel; j++)
{
if (_Hashes[i][j] is FakeHash fake)
{
salts[i][fakeJ++] = fake.Salt;
}
if (_Hashes[i][j] is RealHash real)
{
feeVariations[i][realJ++] = real.FeeVariation;
}
_Hashes[i][j].Commitment = commitments[i][j];
}
}
InternalState.Status = PromiseClientStates.WaitingCommitmentsProof;
return(new ClientRevelation(fakeIndices.ToArray(), InternalState.IndexSalt, salts, feeVariations));
}
public SignaturesRequest CreateSignatureRequest(Script cashoutDestination, FeeRate feeRate)
{
// Steps 2-4
// Almost done, just need to figure out the Transaction CashOut things.
if (cashoutDestination == null)
{
throw new ArgumentNullException(nameof(cashoutDestination));
}
if (feeRate == null)
{
throw new ArgumentNullException(nameof(feeRate));
}
AssertState(PromiseClientStates.WaitingSignatureRequest);
Transaction cashout = new Transaction();
// TODO: Figure out the cashout format to give j Bitcoins to Bob and Q-J to the Tumbler
cashout.AddInput(new TxIn(InternalState.EscrowedCoin.Outpoint));
cashout.Inputs[0].ScriptSig = new Script(
Op.GetPushOp(TrustedBroadcastRequest.PlaceholderSignature),
Op.GetPushOp(TrustedBroadcastRequest.PlaceholderSignature),
Op.GetPushOp(InternalState.EscrowedCoin.Redeem.ToBytes())
);
cashout.AddOutput(new TxOut(InternalState.EscrowedCoin.Amount, cashoutDestination));
cashout.Outputs[0].Value -= feeRate.GetFee(cashout.GetVirtualSize());
// If each payment level requires a different cashOut, then this
// should be moved to the first loop.
HashBase[][] hashes = new HashBase[_Parameters.PaymentsCount][]; //2D
for (int i = 0; i < _Parameters.PaymentsCount; i++)
{
hashes[i] = new HashBase[_Parameters.GetTotalTransactionsCountPerLevel()];
for (int j = 0; j < Parameters.RealTransactionCountPerLevel; j++)
{
RealHash h = new RealHash(cashout, InternalState.EscrowedCoin)
{
FeeVariation = Money.Satoshis(i)
};
hashes[i][j] = h;
}
for (int j = Parameters.RealTransactionCountPerLevel; j < hashes[i].Length; j++)
{
FakeHash h = new FakeHash(Parameters)
{
Salt = new uint256(RandomUtils.GetBytes(32))
};
hashes[i][j] = h;
}
}
_Hashes = hashes;
// Under the assumption that given the same seed the Shuffle will be deterministic.
// TODO: Verify this in Debugging or a unit test.
var shuffleSeed = RandomUtils.GetInt32();
for (int i = 0; i < _Parameters.PaymentsCount; i++)
{
NBitcoin.Utils.Shuffle(_Hashes[i], shuffleSeed);
}
for (int i = 0; i < _Parameters.PaymentsCount; i++)
{
for (int j = 0; j < _Hashes[i].Length; j++)
{
_Hashes[i][j].Index = j;
}
}
var fakeIndices = _Hashes.First().OfType <FakeHash>().Select(h => h.Index).ToArray();
uint256 indexSalt = null;
var request = new SignaturesRequest
{
// This looks cool, but double check the use of Select in debugging.
Hashes = _Hashes.Select(h => (h.Select(k => k.GetHash()).ToArray())).ToArray(),
FakeIndexesHash = PromiseUtils.HashIndexes(ref indexSalt, fakeIndices),
};
InternalState.IndexSalt = indexSalt;
InternalState.Cashout = cashout.Clone();
InternalState.Status = PromiseClientStates.WaitingCommitments;
InternalState.FakeColumns = fakeIndices;
return(request);
}
