static BlockCipher createBlockCipher(int encAlgorithm)
        throws PGPException
    {
        BlockCipher engine;

        switch (encAlgorithm)
        {
        case SymmetricKeyAlgorithmTags.AES_128:
        case SymmetricKeyAlgorithmTags.AES_192:
        case SymmetricKeyAlgorithmTags.AES_256:
            engine = new AESEngine();
            break;
        case SymmetricKeyAlgorithmTags.BLOWFISH:
            engine = new BlowfishEngine();
            break;
        case SymmetricKeyAlgorithmTags.CAST5:
            engine = new CAST5Engine();
            break;
        case SymmetricKeyAlgorithmTags.DES:
            engine = new DESEngine();
            break;
        case SymmetricKeyAlgorithmTags.TWOFISH:
            engine = new TwofishEngine();
            break;
        case SymmetricKeyAlgorithmTags.TRIPLE_DES:
            engine = new DESedeEngine();
            break;
        default:
            throw new PGPException("cannot recognise cipher");
        }

        return engine;
    }