Re: [RFC][PATCH] Make cryptoapi non-optional?

[David Wagner]

David Lang  wrote:
>On Mon, 18 Aug 2003, Andreas Dilger wrote:
>> It wasn't even vanishingly small...  We had a problem in our code where
>> two readers got the same 64-bit value calling get_random_bytes(), and
>> we were depending on this 64-bit value being unique.  This problem was
>> fixed by putting a spinlock around the call to get_random_bytes().
>
>if the number is truely random then there should be a (small but finite)
>chance that any two reads will return the same data. counting on a random
>number to be unique is not a good idea.

Have you ever worked out how small a number 2^-64 is?
You might be surprised.  For most practical purposes, 2^-64 is
effectively zero.

If you see a 64-bit values repeat twice in a row when querying a
cryptographic pseudorandom generator, the crypto-PRNG is almost surely
broken.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/