Re: DRBG seeding

From: Herbert Xu
Date: Fri Apr 17 2015 - 22:16:58 EST


On Sat, Apr 18, 2015 at 04:04:14AM +0200, Stephan Mueller wrote:
>
> However, the only serious solution I can offer to not block is to use my
> Jitter RNG which delivers entropy in (almost all) use cases. See [1]. The code
> is relatively small and does not have any dependencies. In this case, we could
> perform the initialization of the DRBG as follows:
>
> 1. pull buffer of size entropy + nonce from get_random_bytes
>
> 2. pull another buffer of size entropy + nonce from my Jitter RNG
>
> 3. XOR both

Don't xor them. Just provide them both as input to the seed
function.

> 4. seed the DRBG with it
>
> 5. trigger the async invocation of the in-kernel /dev/random
>
> 6. return the DRBG instance to the caller without waiting for the completion
> of step 5
>
> This way, we will get entropy during the first initialization without
> blocking. After speaking with mathematicians at NIST, that Jitter RNG approach
> would be accepted. Note, I personally think that the Jitter RNG has sufficient
> entropy in almost all circumstances (see the massive testing I conducted on
> all more widely used CPUs).
>
> [1] http://www.chronox.de/jent.html

OK this sounds like it should satisfy everybody.

Thanks,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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