private void InitUpdateSign(SignatureParameters param)
{
NtruSign ntru = new NtruSign(param);
SignatureKeyPair kp = ntru.generateKeyPair();
Random rng = new Random();
byte[] msg = new byte[10 + rng.Next(1000)];
rng.NextBytes(msg);
// sign and verify a message in two pieces each
ntru.initSign(kp);
int splitIdx = rng.Next(msg.Length);
ntru.update(ArrayUtils.CopyOf(msg, splitIdx)); // part 1 of msg
byte[] s = ntru.sign(ArrayUtils.CopyOfRange(msg, splitIdx, msg.Length)); // part 2 of msg
ntru.initVerify(kp.pub);
splitIdx = rng.Next(msg.Length);
ntru.update(ArrayUtils.CopyOf(msg, splitIdx)); // part 1 of msg
ntru.update(ArrayUtils.CopyOfRange(msg, splitIdx, msg.Length)); // part 2 of msg
bool valid = ntru.verify(s);
Assert.True(valid);
// verify the same signature with the one-step method
valid = ntru.verify(msg, s, kp.pub);
Assert.True(valid);
// sign using the one-step method and verify using the multi-step method
s = ntru.sign(msg, kp);
ntru.initVerify(kp.pub);
splitIdx = rng.Next(msg.Length);
ntru.update(ArrayUtils.CopyOf(msg, splitIdx)); // part 1 of msg
ntru.update(ArrayUtils.CopyOfRange(msg, splitIdx, msg.Length)); // part 2 of msg
valid = ntru.verify(s);
Assert.True(valid);
}
private void SignVerify(SignatureParameters param)
{
NtruSign ntru = new NtruSign(param);
SignatureKeyPair kp = ntru.generateKeyPair();
Assert.Equals(param.B + 1, kp.priv.getNumBases());
Random rng = new Random();
byte[] msg = new byte[10 + rng.Next(1000)];
rng.NextBytes(msg);
// sign and verify
byte[] s = ntru.sign(msg, kp);
bool valid = ntru.verify(msg, s, kp.pub);
Assert.True(valid);
// altering the signature should make it invalid
s[rng.Next(param.N)] += 1;
valid = ntru.verify(msg, s, kp.pub);
Assert.False(valid);
// test that a random signature fails
rng.NextBytes(s);
valid = ntru.verify(msg, s, kp.pub);
Assert.False(valid);
// encode, decode keypair, test
SignaturePrivateKey priv = new SignaturePrivateKey(kp.priv.getEncoded());
SignaturePublicKey pub = new SignaturePublicKey(kp.pub.getEncoded());
kp = new SignatureKeyPair(priv, pub);
s = ntru.sign(msg, kp);
valid = ntru.verify(msg, s, kp.pub);
Assert.True(valid);
// altering the signature should make it invalid
s[rng.Next(s.Length)] += 1;
valid = ntru.verify(msg, s, kp.pub);
Assert.False(valid);
// sparse/dense
param.sparse = !param.sparse;
s = ntru.sign(msg, kp);
valid = ntru.verify(msg, s, kp.pub);
Assert.True(valid);
s[rng.Next(s.Length)] += 1;
valid = ntru.verify(msg, s, kp.pub);
Assert.False(valid);
param.sparse = !param.sparse;
// decrease NormBound to force multiple signing attempts
SignatureParameters params2 = param.Clone();
params2.normBoundSq *= (float)4.0 / 9; // works for APR2011_439_PROD but may need to be increased for different params
params2.signFailTolerance = 10000;
ntru = new NtruSign(params2);
s = ntru.sign(msg, kp);
valid = ntru.verify(msg, s, kp.pub);
Assert.True(valid);
// test KeyGenAlg.FLOAT (default=RESULTANT)
params2 = param.Clone();
param.keyGenAlg = KeyGenAlg.FLOAT;
ntru = new NtruSign(param);
kp = ntru.generateKeyPair();
s = ntru.sign(msg, kp);
valid = ntru.verify(msg, s, kp.pub);
Assert.True(valid);
s[rng.Next(s.Length)] += 1;
valid = ntru.verify(msg, s, kp.pub);
Assert.False(valid);
}