public Object clone() throws CloneNotSupportedException 
{
        if (this instanceof Cloneable) {
            return super.clone();
        } else {
            throw new CloneNotSupportedException();
        }
}

Returns a clone if the implementation is cloneable.

 abstract protected byte[] engineDigest()
Completes the hash computation by performing final
operations such as padding. Once engineDigest has
been called, the engine should be reset (see
engineReset ).
Resetting is the responsibility of the
engine implementor.

 protected int engineDigest(byte[] buf,
    int offset,
    int len) throws DigestException 
{
        byte[] digest = engineDigest();
        if (len <  digest.length)
                throw new DigestException("partial digests not returned");
        if (buf.length - offset <  digest.length)
                throw new DigestException("insufficient space in the output "
                                          + "buffer to store the digest");
        System.arraycopy(digest, 0, buf, offset, digest.length);
        return digest.length;
}

Completes the hash computation by performing final operations such as padding. Once engineDigest has been called, the engine should be reset (see engineReset ). Resetting is the responsibility of the engine implementor. This method should be abstract, but we leave it concrete for binary compatibility. Knowledgeable providers should override this method.

 protected int engineGetDigestLength() 
{
        return 0;
}

Returns the digest length in bytes.

This concrete method has been added to this previously-defined abstract class. (For backwards compatibility, it cannot be abstract.)

The default behavior is to return 0.

This method may be overridden by a provider to return the digest length.

 abstract protected  void engineReset()
Resets the digest for further use.

 abstract protected  void engineUpdate(byte input)
Updates the digest using the specified byte.

 protected  void engineUpdate(ByteBuffer input) 
{
        if (input.hasRemaining() == false) {
            return;
        }
        if (input.hasArray()) {
            byte[] b = input.array();
            int ofs = input.arrayOffset();
            int pos = input.position();
            int lim = input.limit();
            engineUpdate(b, ofs + pos, lim - pos);
            input.position(lim);
        } else {
            int len = input.remaining();
            int n = JCAUtil.getTempArraySize(len);
            if ((tempArray == null) || (n  > tempArray.length)) {
                tempArray = new byte[n];
            }
            while (len  > 0) {
                int chunk = Math.min(len, tempArray.length);
                input.get(tempArray, 0, chunk);
                engineUpdate(tempArray, 0, chunk);
                len -= chunk;
            }
        }
}

Update the digest using the specified ByteBuffer. The digest is updated using the input.remaining() bytes starting at input.position(). Upon return, the buffer's position will be equal to its limit; its limit will not have changed.

 abstract protected  void engineUpdate(byte[] input,
    int offset,
    int len)
Updates the digest using the specified array of bytes,
starting at the specified offset.