byte[] getHMAC(byte[] msg, int start, int len) throws SaslException {
      intToByte(mySeqNum);
      return calculateHMAC(myKey, seqNum, msg, start, len);
    }
Helper class for providing integrity protection.
hbase-common/src/main/java/org/apache/hadoop/hbase/io/crypto/aes/CryptoAES.java