Re: MDC packet in inter-operation with openpgpjs

You need to call setWithIntegrityPacket(true) on the
JcePGPDataEncryptorBuilder.

Regards,

David

On 08/08/18 16:11, Lou Wynn wrote:
>
> Hi,
>
> I have a Java server app that uses BC to encrypt data. The client
> running in a browser uses the OpenPGPJS (v3.x) to decrypt it. In the
> default mode I get this error from OpenPGPJS:
>
> Error decrypting message: Decryption failed due to missing MDC.     at
> SymmetricallyEncrypted._callee$ (openpgp.js:49622)     at tryCatch
> (openpgp.js:26630)     at Generator.invoke [as _invoke]
> (openpgp.js:26864)     at Generator.prototype.(anonymous function) [as
> next]
> (chrome-extension://dmeinfklhaiihnaiiaiimanofkcmefpa/background.js:28478:21)
>     at step (openpgp.js:4012)     at openpgp.js:4030     at new
> Promise (<anonymous>)     at new F (openpgp.js:9832)     at
> SymmetricallyEncrypted.<anonymous> (openpgp.js:4009)     at
> SymmetricallyEncrypted.decrypt (openpgp.js:49638)
>
>
> If I disable the MDC feature by setting
> "openpgp.config.ignore_mdc_error = true;" then the error is gone.
>
> When I looked at my BC code, I found that the
> PGPEncryptedDataGenerator does add a MDC packet in its close()
> function, which reads like this:
>
> // hand code a mod detection packet // BCPGOutputStream bOut = new
> BCPGOutputStream(genOut, PacketTags.MOD_DETECTION_CODE, 20);
>
>
> Could anyone help me point out where I did wrong? My BC code that
> encrypts is as follows.
>
> byte[] signEncrypt(final PGPPrivateKey priKey,
>             final PGPPublicKey encKey, final byte[] bytes) {
>     try {
>             // Prepare to sign
>             PGPSignatureGenerator sigG = null;
>             if (priKey != null) {
>                 sigG = new PGPSignatureGenerator(new
> JcaPGPContentSignerBuilder(
>                         priKey.getPublicKeyPacket().getAlgorithm(),
> KeyGen.SignatureHash)
>                                 .setProvider(Provider));
>                 sigG.init(PGPSignature.BINARY_DOCUMENT, priKey);
> //                log.info("Signing key is {}",
> Long.toHexString(priKey.getKeyID()));
>             }
>
>             // Encrypt
>             ByteArrayOutputStream bout = new ByteArrayOutputStream();
>             PGPEncryptedDataGenerator encGen = new
> PGPEncryptedDataGenerator(
>                     new
> JcePGPDataEncryptorBuilder(EncAlg).setSecureRandom(Random)
>                             .setProvider(Provider));
>             encGen.addMethod(new
> JcePublicKeyKeyEncryptionMethodGenerator(encKey)
>                     .setProvider(Provider));
>             OutputStream encOut = encGen.open(bout, new byte[BufferSize]);
>             BCPGOutputStream bcOut = null;
>
>             // Compress data before encryption
>             if (pgpCompressed) {
>                 PGPCompressedDataGenerator compG = new
> PGPCompressedDataGenerator(
>                         PGPCompressedData.ZIP);
>                 bcOut = new BCPGOutputStream(compG.open(encOut));
>             }
>             else {
>                 bcOut = new BCPGOutputStream(encOut);
>             }
>
>             if (sigG != null)
>                 sigG.generateOnePassVersion(false).encode(bcOut);
>
>             // Write to pgp object
>             PGPLiteralDataGenerator literalG = new
> PGPLiteralDataGenerator();
>             OutputStream ldOut = literalG.open(bcOut,
> PGPLiteralData.BINARY,
>                     PGPLiteralData.CONSOLE, bytes.length, new Date());
>
>             ByteArrayInputStream bIn = new ByteArrayInputStream(bytes);
>             byte[] buf = new byte[BufferSize];
>             for (int n = 0; (n = bIn.read(buf)) >= 0;) {
>                 ldOut.write(buf, 0, n);
>                 if (sigG != null)
>                     sigG.update(buf, 0, n);
>             }
>
>             if (sigG != null) {
>                 sigG.generate().encode(bcOut);
>             }
>             ldOut.close();
>             bcOut.close();
>             encGen.close();
>
>             return bout.toByteArray();
>         }
>         catch (PGPException | IOException e) {
>             throw new CryptoServiceException(e);
>         }
>     }
>
>
> -- 
> Thanks,
> Lou
>