*/
    private Crypto () {}


    /**
     * 
     * @return MD4 digest
     */
    public static MessageDigest getMD4 () {
        try {
            return MessageDigest.getInstance("MD4", getProvider());
        }
        catch ( NoSuchAlgorithmException e ) {
            throw new CIFSUnsupportedCryptoException(e);
        }
    }


    /**
     * 
     * @return MD5 digest
     */

        case Smb2Constants.SMB2_DIALECT_0302:
            signingKey = Smb3KeyDerivation.deriveSigningKey(dialect, sessionKey, new byte[0] /* unimplemented */);
            m = Mac.getInstance("AESCMAC", Crypto.getProvider());
            break;
        case Smb2Constants.SMB2_DIALECT_0311:
            if ( preauthIntegrityHash == null ) {
                throw new IllegalArgumentException("Missing preauthIntegrityHash for SMB 3.1");