/**
* @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;
}
}
/**
* Alternate to verifySignature() using java.security libraries.
*
* @throws GeneralSecurityException if algorithm unvailable or on other errors
* @since 0.8.7
*/
private boolean altVerifySigSHA1(Signature signature, byte[] data, SigningPublicKey verifyingKey)
throws GeneralSecurityException {
java.security.Signature jsig = java.security.Signature.getInstance("SHA1withDSA");
KeyFactory keyFact = KeyFactory.getInstance("DSA");
// y p q g
KeySpec spec =
new DSAPublicKeySpec(
new NativeBigInteger(1, verifyingKey.getData()),
CryptoConstants.dsap,
CryptoConstants.dsaq,
CryptoConstants.dsag);
PublicKey pubKey = keyFact.generatePublic(spec);
jsig.initVerify(pubKey);
jsig.update(data);
boolean rv = jsig.verify(sigBytesToASN1(signature.getData()));
// if (!rv) {
// System.out.println("BAD SIG\n" + net.i2p.util.HexDump.dump(signature.getData()));
// System.out.println("BAD SIG\n" +
// net.i2p.util.HexDump.dump(sigBytesToASN1(signature.getData())));
// }
return rv;
}
