XOR and ADD subtil difference ?

From: Arnaud Carré (arnaud.carre_at_nospam.com)
Date: 11/30/04 

Date: Tue, 30 Nov 2004 00:12:42 +0100

Hi all,

I wonder if there is a "security" difference between XOR and ADD ? I mean,
let's take random-number generator using external entropy source. Some of
them uses XOR to mix entropy to current state, some of them use XOR. Ex,
quote from the good TrueCrypt :

'Random values are written to the pool by adding (not by replacing the old
values in the pool).'
Do you thing guys security should be changed if XOR is used ? Could you
explain a bit ? ( whatever the answer is yes or no (I guess it's "no" but I
don't know why))

Other: AES uses plenty of XOR like many block cyphers. ( let's say on 32bits
integer in 32bits implementation). What do you think of the security of a
"modifyed" AES using ADD instead of XOR ??

thanks to share your knowledge.

Arnaud

Relevant Pages

  • Hand Waving vs. Rigorous Analysis... (was Security Engineering vs. Crypto Academics...)
    ... Either way, the XOR is pointless. ... >> to improve security. ... Very small changes can make an analysis harder. ... changes, while popular with crypto novices, often do little or nothing ...
    (sci.crypt)
  • re:RFID tags and XOR
    ... everytime you start playing ... with messages it`s easily broken due to XOR, its security is crap. ...
    (sci.crypt)
  • Re: homomorphic encryption
    ... >I couldn't see how the requested property would contribute ... >to security instead of the opposite. ... here is a scheme that is homomorphic w.r.t. XOR and is ... The scheme can encrypt ...
    (sci.crypt)
  • Re: XOR and ADD subtil difference ?
    ... > let's take random-number generator using external entropy source. ... > them uses XOR to mix entropy to current state, ... I think that quote simply means that the number of values in the pool ... You mean ADD modulo something? ...
    (sci.crypt)