Michael Jung mjung at
Thu Oct 28 07:05:13 CDT 2004

On Thursday 28 October 2004 12:46, Shachar Shemesh wrote:
> Alexandre Julliard wrote:
> >Juan Lang <juan_lang at> writes:
> >>Looks good to me, Michael, though I'd suggest using /dev/random rather
> >>than /dev/urandom: the blocking behavior of the former shouldn't be a
> >>problem for Wine (since this DLL makes no timing guarantees anyway).
> >
> >That doesn't mean we want to block, especially for things like
> >CPGenRandom that don't require the highest quality randomness. I think
> >in general /dev/urandom is a much better choice.
> I'm with Juan here. I think urandom is not good enough.
> In general, /dev/random should be used when cryptographic keys are
> required. MSDN is fairly clear on this matter

If I use /dev/random in my patch the unit tests take more than three minutes 
without any user interaction. As to be expected, it runs faster if I move the 
mouse around wildly to generate entropy => 

Since the typical user clicks around wildly whenever the UI doesn't respond 
anymore, we will just do fine ;)

I think both alternatives are badly broken. I've taken a look into OpenSSL's 
RAND_bytes implementation:

> #ifdef DEVRANDOM
>    /* Use a random entropy pool device. Linux, FreeBSD and OpenBSD
>     * have this. Use /dev/urandom if you can as /dev/random may block
>     * if it runs out of random entries.  */

It seems that even the OpenSSL guys didn't find a good solution. The current 
rsaenh.dll implementation has more severe security flaws than this (e.g. 
storing the user's private keys in the registry in plaintext). Thus, for the 
moment I would opt for staying with /dev/urandom.


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