private Mac mac() throws IOException {
        try {
            final Mac mac = Mac.getInstance(this.alg);
            mac.init(this.key);
            return mac;
        } catch (final NoSuchAlgorithmException | InvalidKeyException err) {
            throw new IOException(err);
        }
    }
private Mac mac ( ) throws IOException { try { final Mac mac = Mac . getInstance ( this . alg ) ; mac . init ( this . key ) ; return mac ; } catch ( final NoSuchAlgorithmException | InvalidKeyException err ) { throw new IOException ( err ) ; } }
Obtain MAC instance.
@return Initialized MAC
@throws IOException If algorithm missed or invalid key