The spec. doesn't define behavior for the method
MessageDigestSpi.engineUpdate(byte[] input, int offset, int len)
when one of its parameters is illegal.

The spec says:
  "protected abstract void engineUpdate(byte[] input, int offset, int len)

   Updates the digest using the specified array of bytes, starting at
   the specified offset.

   Parameters:
       input - the array of bytes to use for the update.
       offset - the offset to start from in the array of bytes.
       len - the number of bytes to use, starting at offset."

So, the spec. should define the method behavior when:
1) 'input' array is null
2) 'offset' is outside 'input' array bounds.
3) 'len' is less then zero or
   'offset' + 'len' is outside 'input' array bounds.

###@###.### 2004-02-26