[21628] in cryptography@c2.net mail archive
Re: Creativity and security
daemon@ATHENA.MIT.EDU (brucee@chunder.com)
Mon Mar 27 16:34:03 2006
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Mon, 27 Mar 2006 15:41:23 -0500
From: brucee@chunder.com
To: cryptography@metzdowd.com
regardingg the XXXing on receipts it turns out that things aren't
as grim as i thought. i anlayzed the checksum algorithm and if
you are missing n digits there are 10^(n-1) clashes.
i verified this with a brute force program.
but in the "photograph the card" scenario ... if one digit is
blurry then you still win because 10^(n-1) is 1.
if two are unknown then mr nasty could try buying stuff from
10 diferent sites.
brucee
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