/// <returns>unblinded signature</returns>
public byte[] UnblindSignature(byte[] blindedSignature, BigInteger blindingFactor)
{
var blindingEngine = new RsaBlindingEngine();
var blindingParams = new RsaBlindingParameters(KeyParameters, blindingFactor);
blindingEngine.Init(forEncryption: false, param: blindingParams);
return(blindingEngine.ProcessBlock(blindedSignature, 0, blindedSignature.Length));
}
public byte[] GetUnblindedSignature(byte[] blindedSignature)
{
RsaBlindingEngine blindingEngine = new RsaBlindingEngine();
blindingEngine.Init(false, blindingParams);
byte[] unblindedSignature = blindingEngine.ProcessBlock(blindedSignature, 0, blindedSignature.Length);
return(unblindedSignature);
}
public Game CreateGame(byte[] signature)
{
var blindingEngine = new RsaBlindingEngine();
blindingEngine.Init(false, blindingParams);
return(new Game(gameData, blindingEngine.ProcessBlock(signature, 0, signature.Length)));
}
public Coin CreateCoin(byte[] signature)
{
// "Unblind" the bank's signature (so to speak) and create a new coin
// using the ID and the unblinded signature.
RsaBlindingEngine blindingEngine = new RsaBlindingEngine();
blindingEngine.Init(false, blindingParams);
byte[] s = blindingEngine.ProcessBlock(signature, 0, signature.Length);
return(new Coin(coinID, s));
}
private void testSig(
int id,
RsaKeyParameters pub,
RsaKeyParameters prv,
byte[] slt,
byte[] msg,
byte[] sig)
{
RsaBlindingFactorGenerator blindFactorGen = new RsaBlindingFactorGenerator();
RsaBlindingEngine blindingEngine = new RsaBlindingEngine();
PssSigner blindSigner = new PssSigner(blindingEngine, new Sha1Digest(), 20);
PssSigner signer = new PssSigner(new RsaEngine(), new Sha1Digest(), 20);
blindFactorGen.Init(pub);
BigInteger blindFactor = blindFactorGen.GenerateBlindingFactor();
RsaBlindingParameters parameters = new RsaBlindingParameters(pub, blindFactor);
// generate a blind signature
blindSigner.Init(true, new ParametersWithRandom(parameters, new FixedRandom(slt)));
blindSigner.BlockUpdate(msg, 0, msg.Length);
byte[] blindedData = blindSigner.GenerateSignature();
RsaEngine signerEngine = new RsaEngine();
signerEngine.Init(true, prv);
byte[] blindedSig = signerEngine.ProcessBlock(blindedData, 0, blindedData.Length);
// unblind the signature
blindingEngine.Init(false, parameters);
byte[] s = blindingEngine.ProcessBlock(blindedSig, 0, blindedSig.Length);
//signature verification
if (!AreEqual(s, sig))
{
Fail("test " + id + " failed generation");
}
//verify signature with PssSigner
signer.Init(false, pub);
signer.BlockUpdate(msg, 0, msg.Length);
if (!signer.VerifySignature(s))
{
Fail("test " + id + " failed PssSigner verification");
}
}
private bool isProcessingOkay(
RsaKeyParameters pub,
RsaKeyParameters prv,
byte[] data,
SecureRandom random)
{
RsaBlindingFactorGenerator blindFactorGen = new RsaBlindingFactorGenerator();
RsaBlindingEngine blindingEngine = new RsaBlindingEngine();
PssSigner blindSigner = new PssSigner(blindingEngine, new Sha1Digest(), 20);
PssSigner pssEng = new PssSigner(new RsaEngine(), new Sha1Digest(), 20);
random.NextBytes(data);
blindFactorGen.Init(pub);
BigInteger blindFactor = blindFactorGen.GenerateBlindingFactor();
RsaBlindingParameters parameters = new RsaBlindingParameters(pub, blindFactor);
// generate a blind signature
blindSigner.Init(true, new ParametersWithRandom(parameters, random));
blindSigner.BlockUpdate(data, 0, data.Length);
byte[] blindedData = blindSigner.GenerateSignature();
RsaEngine signerEngine = new RsaEngine();
signerEngine.Init(true, prv);
byte[] blindedSig = signerEngine.ProcessBlock(blindedData, 0, blindedData.Length);
// unblind the signature
blindingEngine.Init(false, parameters);
byte[] s = blindingEngine.ProcessBlock(blindedSig, 0, blindedSig.Length);
//verify signature with PssSigner
pssEng.Init(false, pub);
pssEng.BlockUpdate(data, 0, data.Length);
return(pssEng.VerifySignature(s));
}
