SSH DSA logins on crank.

[david at lang.hm]

On Tue, 20 May 2008, Bernie Innocenti wrote:

> Chris Ball wrote:
>> I've disabled logins with DSA keys on dev.laptop.org.  Turns out that
>> while your RSA key is only vulnerable if *created* on a weak Debian or
>> Ubuntu machine, your DSA key is vulnerable if *used* on Debian/Ubuntu¹,
>> due to DSA having a greater reliance on randomness.
>
> Hopefully this doesn't mean that the _private_ DSA key can be
> compromised if the _public_ key was copied on a Debian/Ubuntu machine.
> If something like this was even possible, as it would make the whole
> asymmetrical key scheme rather useless :-)

the argument is that the PRNG used by buggy versions is predictable and so 
someone could observe the communication and brute-force attack the 
handshake, deciphering the key in the process.

David Lang