/**
* @param hash either a Hash or a SHA1Hash
* @since 0.8.3
*/
private boolean verifySig(
Signature signature, SimpleDataStructure hash, SigningPublicKey verifyingKey) {
long start = _context.clock().now();
try {
byte[] sigbytes = signature.getData();
byte rbytes[] = new byte[20];
byte sbytes[] = new byte[20];
// System.arraycopy(sigbytes, 0, rbytes, 0, 20);
// System.arraycopy(sigbytes, 20, sbytes, 0, 20);
for (int x = 0; x < 40; x++) {
if (x < 20) {
rbytes[x] = sigbytes[x];
} else {
sbytes[x - 20] = sigbytes[x];
}
}
BigInteger s = new NativeBigInteger(1, sbytes);
BigInteger r = new NativeBigInteger(1, rbytes);
BigInteger y = new NativeBigInteger(1, verifyingKey.getData());
BigInteger w = null;
try {
w = s.modInverse(CryptoConstants.dsaq);
} catch (ArithmeticException ae) {
_log.warn("modInverse() error", ae);
return false;
}
byte data[] = hash.getData();
NativeBigInteger bi = new NativeBigInteger(1, data);
BigInteger u1 = bi.multiply(w).mod(CryptoConstants.dsaq);
BigInteger u2 = r.multiply(w).mod(CryptoConstants.dsaq);
BigInteger modval = CryptoConstants.dsag.modPow(u1, CryptoConstants.dsap);
BigInteger modmulval = modval.multiply(y.modPow(u2, CryptoConstants.dsap));
BigInteger v = (modmulval).mod(CryptoConstants.dsap).mod(CryptoConstants.dsaq);
boolean ok = v.compareTo(r) == 0;
long diff = _context.clock().now() - start;
if (diff > 1000) {
if (_log.shouldLog(Log.WARN))
_log.warn("Took too long to verify the signature (" + diff + "ms)");
}
return ok;
} catch (Exception e) {
_log.log(Log.CRIT, "Error verifying the signature", e);
return false;
}
}
/**
* @param hash either a Hash or a SHA1Hash
* @since 0.8.3
*/
private Signature signIt(SimpleDataStructure hash, SigningPrivateKey signingKey) {
if ((signingKey == null) || (hash == null)) return null;
long start = _context.clock().now();
Signature sig = new Signature();
BigInteger k;
boolean ok = false;
do {
k = new BigInteger(160, _context.random());
ok = k.compareTo(CryptoConstants.dsaq) != 1;
ok = ok && !k.equals(BigInteger.ZERO);
// System.out.println("K picked (ok? " + ok + "): " + k.bitLength() + ": " + k.toString());
} while (!ok);
BigInteger r = CryptoConstants.dsag.modPow(k, CryptoConstants.dsap).mod(CryptoConstants.dsaq);
BigInteger kinv = k.modInverse(CryptoConstants.dsaq);
BigInteger M = new NativeBigInteger(1, hash.getData());
BigInteger x = new NativeBigInteger(1, signingKey.getData());
BigInteger s = (kinv.multiply(M.add(x.multiply(r)))).mod(CryptoConstants.dsaq);
byte[] rbytes = r.toByteArray();
byte[] sbytes = s.toByteArray();
byte[] out = new byte[40];
// (q^random)%p is computationally random
_context.random().harvester().feedEntropy("DSA.sign", rbytes, 0, rbytes.length);
if (rbytes.length == 20) {
// System.arraycopy(rbytes, 0, out, 0, 20);
for (int i = 0; i < 20; i++) {
out[i] = rbytes[i];
}
} else if (rbytes.length == 21) {
// System.arraycopy(rbytes, 1, out, 0, 20);
for (int i = 0; i < 20; i++) {
out[i] = rbytes[i + 1];
}
} else {
if (_log.shouldLog(Log.DEBUG))
_log.debug("Using short rbytes.length [" + rbytes.length + "]");
// System.arraycopy(rbytes, 0, out, 20 - rbytes.length, rbytes.length);
for (int i = 0; i < rbytes.length; i++) out[i + 20 - rbytes.length] = rbytes[i];
}
if (sbytes.length == 20) {
// System.arraycopy(sbytes, 0, out, 20, 20);
for (int i = 0; i < 20; i++) {
out[i + 20] = sbytes[i];
}
} else if (sbytes.length == 21) {
// System.arraycopy(sbytes, 1, out, 20, 20);
for (int i = 0; i < 20; i++) {
out[i + 20] = sbytes[i + 1];
}
} else {
if (_log.shouldLog(Log.DEBUG))
_log.debug("Using short sbytes.length [" + sbytes.length + "]");
// System.arraycopy(sbytes, 0, out, 40 - sbytes.length, sbytes.length);
for (int i = 0; i < sbytes.length; i++) out[i + 20 + 20 - sbytes.length] = sbytes[i];
}
sig.setData(out);
long diff = _context.clock().now() - start;
if (diff > 1000) {
if (_log.shouldLog(Log.WARN)) _log.warn("Took too long to sign (" + diff + "ms)");
}
return sig;
}
