Re: Please Cure My Ignorance (I know that may be difficult :-)) on Hash Functions

From: Clay Culver (Clay_Culver@yahoo.com)
Date: 02/20/03 

From: Clay_Culver@yahoo.com (Clay Culver)
Date: 20 Feb 2003 07:18:51 -0800

"flip" <flip_alpha@safebunch.com> wrote in message news:
> I think I tried a few examples and saw that SHA-1 changed "all" of the bits
> in the hash output. This is probably from some "information theory" unicity
> distance theory, but I am not sure.
All of them!? Wait, are you sure you were not looking at hex (0-9,
A-F) instead of binary? If you mean that it changed all of them, that
means that it inverted the binary string (bitwise negation), which is
very odd.

If you were looking at hex it would probably be best to output both in
binary to see what is changed... 1 bit (out of 4) of a change in a
nybble will make the hex value change, but actually having all the
bytes change (for several examples, as you said) would be very odd
indeed.

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