/**
* @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;
}
