How thorough are the hash breaks, anyway?

[talli at netway.org]

Ian Grigg writes: 

> Daniel Carosone wrote:
>> There is one application of hashes, however, that fits these
>> limitations very closely and has me particularly worried:
>> certificates.  The public key data is public, and it's a "random"
>> bitpattern where nobody would ever notice a few different bits. 
>> 
>> If someone finds a collision for microsoft's windows update cert (or a
>> number of other possibilities), and the fan is well and truly buried
>> in it.
> 
> Correct me if I'm wrong ... but once finding
> a hash collision on a public key, you'd also
> need to find a matching private key, right?

You are not wrong... you can try to find the right private key for your 
collision too...  ;) 

In fact, looking for a collision to a public certificate is not as easy as 
breaking a signature but breaking many of them at the same time. 

Talliann 

> 
> iang 
> 
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