On hash breaks, was Re: First quantum crypto bank transfer

Joseph Ashwood ashwood at msn.com
Sun Aug 22 16:42:03 EDT 2004

Since the rest has been covered quite well, I will instead focus on the 
comparison of AES and SHA-0, RIPEM, MD5, etc.

----- Original Message ----- 
From: "Jerrold Leichter" <jerrold.leichter at smarts.com>
Subject: Re: First quantum crypto bank transfer

> Alternatively, how anyone can have absolute confidence in conventional 
> crypto
> in a week when a surprise attack appears against a widely-fielded 
> primitive
> like MD5 is beyond me.  Is our certainty about AES's security really any
> better today than was our certainty about RIPEM - or even SHA-0 - was 
> three
> weeks ago?
> -- Jerry

Actually for years the cryptography community has been saying "retire MD5," 
SHA-0 has been required to be replaced by SHA-1 for some time, the RIPEM 
series is functionally-speaking unused and represented the only real 
surprise. Except for RIPEM there were known to be reasons for this, MD5 was 
known to be flawed, SHA-0 was replaced because it was flawed (although 
knowledge of the nature of the flaw was hidden). Even with RIPEM (and SHA-1 
for the same reason) I have plans in place (and have had for some time) the 
move away from 160-bit hashes to larger ones, so the attack on RIPEM had 
little effect on me and my clients, even a full attack on SHA-1 would have 
little effect on the clients that actually listen (they all have backup 
plans that involve the rest of the SHA series and at the very least 

So basically I encourage my clients to maintain good business practices 
which means that they don't need to have belief in the long term security of 
AES, or SHA-1, or RSA, or ......... This is just good business, and it is a 
process that evolved to deal with similar circumstances.

Trust Laboratories
Changing Software Development

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