}

        byte checksum[] = PacMac.calculateMac(this.serverSignature.getType(), keys, checksumData);
        if (!MessageDigest.isEqual(this.serverSignature.getChecksum(), checksum)) {
            if (log.isDebugEnabled()) {
                log.debug(String.format("PAC signature validation failed, have: %s expected: %s type: %d len: %d",

            throw new CIFSException("Preauth integrity context is invalid for session: " + sessionId);
        }

        byte[] actualHash = context.getCurrentHash();
        boolean isValid = MessageDigest.isEqual(actualHash, expectedHash);

        if (isValid) {
            log.debug("Preauth integrity validation passed for session {}", sessionId);
        } else {

        }

        final byte[] verify = new byte[8];
        System.arraycopy(mic, 4, verify, 0, 8);
        if (!MessageDigest.isEqual(trunc, verify)) {
            if (log.isDebugEnabled()) {
                log.debug(String.format("Seq = %d ver = %d encrypted = %s", seq, ver, encrypted));

            System.arraycopy(mac.doFinal(), 0, cmp, 0, SIGNATURE_LENGTH);

            // Use constant-time comparison to prevent timing attacks
            if (!MessageDigest.isEqual(sig, cmp)) {
                return false; // Signature verification failed
            }
            return true; // Signature verification succeeded
        } finally {
            this.signingLock.unlock();