public InputStream decryptStream()

in priam/src/main/java/com/netflix/priam/cryptography/pgp/PgpCryptography.java [97:175]
58 lines of code
8 McCabe index (conditional complexity)

    public InputStream decryptStream(InputStream in, char[] passwd, String objectName)
            throws Exception {

        logger.info("Start to decrypt object: {}", objectName);

        in = PGPUtil.getDecoderStream(in);

        // general class for reading a stream of data.
        PGPObjectFactory inPgpReader = new PGPObjectFactory(in);
        Object o = inPgpReader.nextObject();

        PGPEncryptedDataList encryptedDataList;
        // the first object might be a PGP marker packet.
        if (o instanceof PGPEncryptedDataList) encryptedDataList = (PGPEncryptedDataList) o;
        else
            // first object was a marker, the real data is the next one.
            encryptedDataList = (PGPEncryptedDataList) inPgpReader.nextObject();

        // get the iterator so we can iterate through all the encrypted data.
        Iterator encryptedDataIterator = encryptedDataList.getEncryptedDataObjects();

        // to be use for decryption
        PGPPrivateKey privateKey = null;
        // a handle to the encrypted data stream
        PGPPublicKeyEncryptedData encryptedDataStreamHandle = null;
        while (privateKey == null && encryptedDataIterator.hasNext()) {
            // a handle to the encrypted data stream
            encryptedDataStreamHandle = (PGPPublicKeyEncryptedData) encryptedDataIterator.next();

            try {
                privateKey =
                        findSecretKey(
                                getPgpSecurityCollection(),
                                encryptedDataStreamHandle.getKeyID(),
                                passwd);
            } catch (Exception ex) {
                throw new IllegalStateException(
                        "decryption exception:  object: "
                                + objectName
                                + ", Exception when fetching private key using key: "
                                + encryptedDataStreamHandle.getKeyID(),
                        ex);
            }
        }
        if (privateKey == null)
            throw new IllegalStateException(
                    "decryption exception:  object: "
                            + objectName
                            + ", Private key for message not found.");

        // finally, lets decrypt the object
        InputStream decryptInputStream = encryptedDataStreamHandle.getDataStream(privateKey, "BC");
        PGPObjectFactory decryptedDataReader = new PGPObjectFactory(decryptInputStream);

        // the decrypted data object is compressed, lets decompress it.
        // get a handle to the decrypted, compress data stream
        PGPCompressedData compressedDataReader =
                (PGPCompressedData) decryptedDataReader.nextObject();
        InputStream compressedStream =
                new BufferedInputStream(compressedDataReader.getDataStream());
        PGPObjectFactory compressedStreamReader = new PGPObjectFactory(compressedStream);
        Object data = compressedStreamReader.nextObject();
        if (data instanceof PGPLiteralData) {
            PGPLiteralData dataPgpReader = (PGPLiteralData) data;
            // a handle to the decrypted, uncompress data stream
            return dataPgpReader.getInputStream();

        } else if (data instanceof PGPOnePassSignatureList) {
            throw new PGPException(
                    "decryption exception:  object: "
                            + objectName
                            + ", encrypted data contains a signed message - not literal data.");
        } else {
            throw new PGPException(
                    "decryption exception:  object: "
                            + objectName
                            + ", data is not a simple encrypted file - type unknown.");
        }
    }