Re: IQ Handling vulnerabilities

On 2/10/14 12:25 PM, "Thijs Alkemade" <[email protected]> wrote:

>Uhm. Maybe this email is missing a line again, but if you use those
>values as
>'id's directly, they will not be unpredictable at all, as anyone who
>receives
>an <iq/> can generate the rest of the chain.
>
>However, if you make sure the 'id' values are only half the hashes, it
>should
>be unpredictable unless an attacker is willing to spend an insane amount
>of
>work.
>
>So:
>
>start = sha1(crytpo_rand())
>start+1 = sha1(start)
>...
>
>id1 = start[0:10]
>id2 = start+1[0:10]

Or add a nonce to each round:

nonce = crytpo_rand()
start = sha1(nonce + crytpo_rand())
start+1 = sha1(nonce + start)

Regardless, there exist solutions.


-- 
Joe Hildebrand