protected override async Task <byte[][]> ReceiveMaskedOptionsAsync(BitArray selectionIndices, BitMatrix tTransposed, int numberOfInvocations, int numberOfMessageBytes)
{
Debug.Assert(selectionIndices.Length == numberOfInvocations);
Debug.Assert(tTransposed.Rows == SecurityParameter);
Debug.Assert(tTransposed.Cols == numberOfInvocations);
// retrieve the masked options from the sender and unmask the one indicated by the
// corresponding selection indices
byte[][][] maskedOptions = await CommunicationTools.ReadOptionsAsync(Channel, 1, numberOfInvocations, numberOfMessageBytes);
Debug.Assert(maskedOptions.Length == numberOfInvocations);
byte[][] results = new byte[numberOfInvocations][];
Parallel.For(0, numberOfInvocations, i =>
{
Debug.Assert(maskedOptions[i].Length == 1);
Debug.Assert(maskedOptions[i][0].Length == numberOfMessageBytes);
RandomOracle randomOracle = RandomOracleProvider.Create();
int s = Convert.ToInt32(selectionIndices[i].Value);
byte[] query = tTransposed.GetColumn((uint)i).ToBytes();
if (s == 0)
{
results[i] = randomOracle.Invoke(query).Take(numberOfMessageBytes).ToArray();
}
else
{
results[i] = randomOracle.Mask(maskedOptions[i][0], query);
}
});
return(results);
}
public NaorPinkasObliviousTransfer(SecurityParameters parameters, CryptoContext cryptoContext)
{
_parameters = parameters;
_randomOracle = new HashRandomOracle(cryptoContext.HashAlgorithmProvider.CreateThreadsafe());
_randomNumberGenerator = new ThreadsafeRandomNumberGenerator(cryptoContext.RandomNumberGenerator);
#if DEBUG
Console.WriteLine("Security parameters:");
Console.WriteLine("p = {0}", _parameters.P);
Console.WriteLine("q = {0}", _parameters.Q);
Console.WriteLine("g = {0}", _parameters.G);
Console.WriteLine("group element size = {0} bytes", _parameters.GroupElementSize);
Console.WriteLine("exponent size = {0} bytes", _parameters.ExponentSize);
#endif
}
public async Task <Pair <byte[]>[]> SendAsync(byte[][] correlationStrings, int numberOfInvocations, int numberOfMessageBytes)
{
if (correlationStrings.Length != numberOfInvocations)
{
throw new ArgumentException("Amount of provided correlation strings must match the specified number of invocations.", nameof(correlationStrings));
}
foreach (byte[] message in correlationStrings)
{
if (message.Length != numberOfMessageBytes)
{
throw new ArgumentException("The length of of at least one correlation string does not match the specified message length.", nameof(correlationStrings));
}
}
BitMatrix q = await ReceiveQMatrix(numberOfInvocations);
Debug.Assert(q.Rows == numberOfInvocations);
Debug.Assert(q.Cols == SecurityParameter);
Pair <byte[]>[] options = new Pair <byte[]> [numberOfInvocations];
byte[][][] maskedOptions = new byte[numberOfInvocations][][];
Parallel.For(0, numberOfInvocations, i =>
{
Debug.Assert(correlationStrings[i].Length == numberOfMessageBytes);
RandomOracle randomOracle = RandomOracleProvider.Create();
options[i] = new Pair <byte[]>();
BitArray qRow = q.GetRow((uint)i);
byte[] query = qRow.ToBytes();
options[i][0] = randomOracle.Invoke(query).Take(numberOfMessageBytes).ToArray();
options[i][1] = ByteBuffer.Xor(correlationStrings[i], options[i][0]);
query = (qRow ^ SenderChoices).ToBytes();
maskedOptions[i] = new[] { randomOracle.Mask(options[i][1], query) };
Debug.Assert(maskedOptions[i][0].Length == numberOfMessageBytes);
});
await CommunicationTools.WriteOptionsAsync(Channel, maskedOptions, 1, numberOfInvocations, numberOfMessageBytes);
return(options);
}
