>>>Mine is slower- but I do not see any other way, it's generic - so I cannot use any operator (!=, ==, etc)
>>True, I hadn't thought about that.
>>
>>>If I take Equals() out and the double index (index1 and index2) they compare
>>>What I'm trying to do is (1) avoid accessing first.Length on each iteration and (2) decrement and compare to zero rather than another value
>>
>>Given the constraint I can't see any way of improving on it!
>>
>>>Bonus: shouldn't you dispose of MD5CryptoServiceProvider() ?
>>In favour of ?
>
>No favour at all, just that it should be disposed since it implements IDisposable

Ah. I was reading plain english not C#. Good point - and, in fact, relevant to another thread here not long ago re whether to assign a class instance to a variable. If I don't do that I can't call Dispose().....