private void step3ValidateSignatureForV() throws Exception {
ECCParameters secp160r1 = ECCTestHelper.getSecp160r1(injector);
MessageDigest md = MessageDigest.getInstance("SHA1");
md.update(messageBytes);
String H = ByteArrayHelper.toHex(md.digest());
// Convert H to a bit string
String bitStringE = ECCTestHelper.toBitStringFromHexString(H);
// Convert the bit string to a hex string
String hexStringE = ECCTestHelper.toHexStringFromBitString(bitStringE);
BigInteger e = new BigInteger(hexStringE, 16);
// Compute u1
BigInteger u1 =
e.multiply(s.modPow(BigInteger.ONE.negate(), secp160r1.getN())).mod(secp160r1.getN());
// Does u1 match our expectation?
BigInteger expectedU1 = new BigInteger("126492345237556041805390442445971246551226394866", 10);
if (!u1.equals(expectedU1)) {
// No, throw an exception
throw new Exception("Failed at 2.1.4 4. u1 didn't match.");
}
// Compute u2
BigInteger u2 =
r.multiply(s.modPow(BigInteger.ONE.negate(), secp160r1.getN())).mod(secp160r1.getN());
// Does u2 match our expectation?
BigInteger expectedU2 = new BigInteger("642136937233451268764953375477669732399252982122", 10);
if (!u2.equals(expectedU2)) {
// No, throw an exception
throw new Exception("Failed at 2.1.4 4. u2 didn't match.");
}
// Compute R = (xR, yR) = u1G + u2Qu
ECCPoint u1G = secp160r1.getG().multiply(u1);
ECCPoint u2Qu = Qu.multiply(u2);
ECCPoint R = u1G.add(u2Qu);
// Validate that R is what we expect
BigInteger expectedXr = new BigInteger("1176954224688105769566774212902092897866168635793", 10);
BigInteger expectedYr = new BigInteger("1130322298812061698910820170565981471918861336822", 10);
// Are the points equal?
if (!R.getX().toBigInteger().equals(expectedXr)) {
// No, throw an exception
throw new Exception("Failed at 2.1.4 5.3. xR didn't match.");
}
if (!R.getY().toBigInteger().equals(expectedYr)) {
// No, throw an exception
throw new Exception("Failed at 2.1.4 5.3. yR didn't match.");
}
// v = xR mod n
BigInteger v = R.getX().toBigInteger().mod(secp160r1.getN());
// Validate that v is what we expect
BigInteger expectedV = new BigInteger("1176954224688105769566774212902092897866168635793", 10);
if (!v.equals(expectedV)) {
// No, throw an exception
throw new Exception("Failed at 2.1.4 7. v didn't match");
}
// Validate that v == r, are they equal?
if (!v.equals(R.getX().toBigInteger())) {
// No, throw an exception
throw new Exception("Failed at 2.1.4 8. v != r");
}
// The message is valid
}
private void step2SigningOperationForU() throws Exception {
ECCParameters secp160r1 = ECCTestHelper.getSecp160r1(injector);
// Selected k value
BigInteger k = new BigInteger("702232148019446860144825009548118511996283736794", 10);
// Compute R = (xR, yR) = k * G
R = secp160r1.getG().multiply(k);
// Validate R
BigInteger xR = new BigInteger("1176954224688105769566774212902092897866168635793", 10);
BigInteger yR = new BigInteger("1130322298812061698910820170565981471918861336822", 10);
// Does xR match?
BigInteger RX = R.getX().toBigInteger();
if (!RX.equals(xR)) {
// No, throw an exception
throw new Exception(
"Failed at 2.1.3 1.2, R doesn't match xR. Expected "
+ xR.toString(16)
+ ", got "
+ RX.toString(16));
}
// Does yR match?
BigInteger RY = R.getY().toBigInteger();
if (!RY.equals(yR)) {
// No, throw an exception
throw new Exception(
"Failed at 2.1.3 1.2, R doesn't match yR. Expected "
+ yR.toString(16)
+ ", got "
+ RY.toString(16));
}
// Derive an integer r from xR (mod n)
r =
new BigInteger("1176954224688105769566774212902092897866168635793", 10)
.mod(secp160r1.getN());
// Is r zero?
if (r.equals(BigInteger.ZERO)) {
// Yes, r cannot be zero
throw new Exception("Failed at 2.1.3 3.2. r cannot be zero.");
}
// Validate r as an octet string
String rOctetString = "ce2873e5be449563391feb47ddcba2dc16379191";
String rString = r.toString(16);
// Is it correct?
if (!ECCTestHelper.compare(rString, rOctetString)) {
// No, throw an exception
throw new Exception("Failed at 2.1.3 3.3. Expected " + rOctetString + ", got " + rString);
}
// Hash the message with SHA-1
MessageDigest md = MessageDigest.getInstance("SHA1");
md.update(messageBytes);
String H = ByteArrayHelper.toHex(md.digest());
// Validate the message hash
String expectedMessageHash = "a9993e364706816aba3e25717850c26c9cd0d89d";
// Is the hash what we expected?
if (!ECCTestHelper.compare(H, expectedMessageHash)) {
// No, throw an exception
throw new Exception("Failed at 2.1.3 4. Expected " + expectedMessageHash + ", got " + H);
}
// Derive e from H
// Convert H to a bit string
String bitStringH = ECCTestHelper.toBitStringFromHexString(H);
// Validate the bit string
String expectedBitString =
"10101001 10011001 00111110 00110110 01000111 00000110 10000001 01101010 10111010 00111110 00100101 01110001 01111000 01010000 11000010 01101100 10011100 11010000 11011000 10011101";
// Are they equal?
if (!ECCTestHelper.compare(bitStringH, expectedBitString)) {
// No, throw an exception
throw new Exception(
"Failed at 2.1.3 5.1. Expected " + expectedBitString + ", got " + bitStringH);
}
int lengthCheckValue = bitStringH.length() % 8;
// TODO - Validate that this is what we should be checking. The notation is a bit unclear to me
// in the docs.
if (lengthCheckValue != 0) {
// No, throw an exception
throw new Exception("Failed at 2.1.3 5.2. Length of bit string for H must be 0 (mod 8).");
}
// Set E string to H string since length H mod 8 equals 0
String bitStringE = new String(bitStringH);
// Convert from the bit string to a hex string
String hexStringE = ECCTestHelper.toHexStringFromBitString(bitStringE);
// Validate the hex string
String expectedHexString = "A9993E364706816ABA3E25717850C26C9CD0D89D";
// Are they equal?
if (!ECCTestHelper.compare(hexStringE, expectedHexString)) {
// No, throw an exception
throw new Exception(
"Failed at 2.1.3 5.3. Expected " + expectedHexString + ", got " + hexStringE);
}
BigInteger E = new BigInteger(hexStringE, 16);
// Validate that E is the correct value
BigInteger expectedE = new BigInteger("968236873715988614170569073515315707566766479517", 10);
// Are they equal?
if (!expectedE.equals(E)) {
// No, throw an exception
throw new Exception("Failed at 2.1.3 5.4. Expected " + expectedE + ", got " + E);
}
// Step 6: Compute the integer s.
// s = k^-1(e + dU * r) (mod n)
s =
k.modPow(BigInteger.ONE.negate(), secp160r1.getN())
.multiply(E.add(dU.multiply(r)))
.mod(secp160r1.getN());
// Validate that s is not zero (mod n)
// Is it zero (mod n)?
if (s.equals(BigInteger.ZERO)) {
// Yes, throw an exception
throw new Exception("s cannot be zero (mod n)");
}
// Validate that s is the value we expect
BigInteger expectedS = new BigInteger("299742580584132926933316745664091704165278518100", 10);
// Is it equal to the value we expect?
if (!s.equals(expectedS)) {
// No, throw an exception
throw new Exception("Failed at 2.1.3 6.1. Expected " + expectedS + ", got " + s);
}
// Validate the octet string representation of the signature
String expectedSOctetString = "3480EC371A091A464B31CE47DF0CB8AA2D98B54";
// Are they equal?
if (ECCTestHelper.compare(s.toString(16), expectedSOctetString)) {
// No, throw an exception
throw new Exception("Failed at 2.1.3 6.3. Expected " + expectedSOctetString + ", got " + s);
}
}