bool SignatureValidate(PK_Signer &priv, PK_Verifier &pub, bool thorough = false)
{
bool pass = true, fail;
fail = !pub.GetMaterial().Validate(GlobalRNG(), thorough ? 3 : 2) || !priv.GetMaterial().Validate(GlobalRNG(), thorough ? 3 : 2);
pass = pass && !fail;
cout << (fail ? "FAILED " : "passed ");
cout << "signature key validation\n";
static const byte message[] = "test message";
const unsigned int messageLen = COUNTOF(message);
SecByteBlock signature(priv.MaxSignatureLength());
size_t signatureLength = priv.SignMessage(GlobalRNG(), message, messageLen, signature);
fail = !pub.VerifyMessage(message, messageLen, signature, signatureLength);
pass = pass && !fail;
cout << (fail ? "FAILED " : "passed ");
cout << "signature and verification\n";
++signature[0];
fail = pub.VerifyMessage(message, messageLen, signature, signatureLength);
pass = pass && !fail;
cout << (fail ? "FAILED " : "passed ");
cout << "checking invalid signature" << endl;
if (priv.MaxRecoverableLength() > 0)
{
signatureLength = priv.SignMessageWithRecovery(GlobalRNG(), message, messageLen, NULL, 0, signature);
SecByteBlock recovered(priv.MaxRecoverableLengthFromSignatureLength(signatureLength));
DecodingResult result = pub.RecoverMessage(recovered, NULL, 0, signature, signatureLength);
fail = !(result.isValidCoding && result.messageLength == messageLen && VerifyBufsEqual(recovered, message, messageLen));
pass = pass && !fail;
cout << (fail ? "FAILED " : "passed ");
cout << "signature and verification with recovery" << endl;
++signature[0];
result = pub.RecoverMessage(recovered, NULL, 0, signature, signatureLength);
fail = result.isValidCoding;
pass = pass && !fail;
cout << (fail ? "FAILED " : "passed ");
cout << "recovery with invalid signature" << endl;
}
return pass;
}
PPMImage PerformAA(const PPMImage& original, const PPMImage& filtered) {
NetPBMLoader loader;
PPMImage recovered(original.getLength(), original.getWidth());
PPMImage maxVarDir(original.getLength(), original.getWidth());
PPMImage sobel(original.getLength(), original.getWidth());
for(int i = 0; i < recovered.getLength(); ++i) {
for(int j = 0; j < recovered.getWidth(); ++j) {
// don't treat border pixels
if(i == 0 || j == 0 || i == recovered.getLength()-1 || j == recovered.getWidth()-1) {
recovered(i,j) = filtered(i,j);
continue;
}
PPMImage neighbors(3,3);
PPMImage neighborsAliased(3,3);
Vector3D pixel = original(i,j);
Vector3D pixelAlias = filtered(i,j);
// colors are changing most rapidly considering this direction
Vector3D varDir;
// the distance vector from the average value of neighbors
Vector3D dAverage[9];
// the average value computed considering the neighbors
Vector3D average;
// parameters to compute recovery
float alpha = 0;
float beta = 0;
float dp = 0;
float Gd = 0;
float ep = 0;
float Ge = 0;
// construct neighbors of aliased and original images
for(int k = i-1; k <= i+1; ++k) {
for(int l = j-1; l <= j+1; ++l) {
neighbors((k-i)+1, (l-j)+1) = original(k,l);
neighborsAliased((k-i)+1, (l-j)+1) = filtered(k,l);
}
}
// compute the average
for(int k = 0; k < neighbors.getLength(); ++k) {
for(int l = 0; l < neighbors.getWidth(); ++l) {
average += neighbors(k,l);
}
}
average /= neighbors.getSize();
// compute the distance from the average color value
for(int k = 0; k < neighbors.getLength(); ++k) {
for(int l = 0; l < neighbors.getWidth(); ++l) {
dAverage[k*neighbors.getLength()+l] = neighbors(k,l) - average;
}
}
varDir = Vector3D(average.normalize() + EPSILON);
EM(dAverage, 3, varDir, neighbors.getSize());
Vector2D maxColorPos;
Vector2D minColorPos;
// compute the two maximum colors along the straight line directed by varDir
if(ExtremeColors(neighbors, varDir, maxColorPos, minColorPos)) {
Vector3D ca = neighbors(minColorPos.x, minColorPos.y);
Vector3D cb = neighbors(maxColorPos.x, maxColorPos.y);
Vector3D cacb = cb - ca;
Vector3D d;
alpha = (pixel - ca).dot(cacb) / cacb.dot(cacb);
d = pixel - (alpha * cacb) - ca;
dp = d.length();
Gd = GAUSS(dp, SIGMA_D);
}
float eo = Sobel(neighbors);
float ef = Sobel(neighborsAliased);
ep = ef * eo;
Ge = GAUSS(ep, SIGMA_E);
Vector3D cbAliased = neighborsAliased(maxColorPos.x, maxColorPos.y);
Vector3D caAliased = neighborsAliased(minColorPos.x, minColorPos.y);
beta = Gd * (1- Ge);
// final composition
recovered(i,j) = beta * (caAliased * (1-alpha) + cbAliased * alpha) + (1-beta) * pixelAlias;
maxVarDir(i,j) = varDir * 255;
sobel(i,j) = Vector3D(sqrt(eo));
}
}
loader.savePPM(maxVarDir, "max_variance_direction");
loader.savePPM(sobel, "sobel");
return recovered;
}
