Re: What is the accepted technical definition of the word break?

From: AE (hidden@nospam.com)
Date: 03/16/03 

From: AE <hidden@nospam.com>
Date: Sun, 16 Mar 2003 11:03:59 +0100

"o������������������������" wrote:
> How would you complete the following paragraph, and are there any problems
> with it as it stands?
>
>
>
> When one says that a break has been discovered for a particular algorithm,
> it does not necessarily mean that an effective means has been found to
> attack the algorithm in practice. A break is a more theoretical concept,
> which actually just means that a technique has been found that ...

in most cases it is number 1: "is faster than brute force".

Only exception are ciphers that were known to allow faster attacks when
being designed:
The keyspace of TripleDES is 168 bit, but the fastest known attack
equals to a keyspace of only 112 bit. Nevertheless TripleDES is not
broken since this fact is well known and accepted.

Maybe one should write "is faster than claimed by the designers?"

AE

> Which of the following best completes the above sentence?
>
>
>
> 1. Is faster than brute force, regardless of how little the improvement is.
>
> 2. Makes the attack polynomial (time w.r.t. key size), assuming that the
> brute force is exponential time
>
> 3. Something else???

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