Re: patch: initialize randpool with zeroes

>
> Jeffrey Walton suggested an improvement to this patch.  Here's the new
> version, which I'm now using in pycryptopp and which seems to work
> fine.  I would recommend a patch like this for Crypto++ trunk.  If Wei
> Dai doesn't want to spend the CPU cycles and to eliminate the
> (questionable) bits of entropy to be found in uninitialized memory,
> then perhaps we could guard it with some sort of #define like
> "PURIFY_CLEAN"/"VALGRIND_CLEAN" or "INITIALIZE_RANDPOOL".
>
> Regards,
>
> Zooko
>
> HACK rgnt1-210-206-dhcp:~/playground/pycryptopp/cryptopp/release-5.6.0-
> plus-zookopatches$ darcs diff -u -p'initialize the randpool'
> Thu Jun  4 07:41:58 MDT 2009  zooko@...
>  * initialize the randpool with zeroes instead of using whatever bits
> were there
>  This makes valgrind stop complaining about using uninitialized
> memory.  There are other ways to make valgrind stop complaining, such
> as by explicitly telling it "See these here bytes?  Pretend from now
> on that they are initialized.", but I don't like using uninitialized
> memory for my randpool anyway.  If my randpool is broken, I would like
> for it to start giving the exact same output time after time (or a
> short cycle, or a selection from a small set, or whatever), so that
> the users and developers can more quickly detect the problem, rather
> than rely for my security on the values in the uninitialized memory,
> which might not be all that unpredictable.
> diff -rN -u old-release-5.6.0-plus-zookopatches/c5/randpool.cpp new-
> release-5.6.0-plus-zookopatches/c5/randpool.cpp
> --- old-release-5.6.0-plus-zookopatches/c5/randpool.cpp 2009-06-04
> 14:18:46.000000000 -0600
> +++ new-release-5.6.0-plus-zookopatches/c5/randpool.cpp 2009-06-04
> 14:18:46.000000000 -0600
> @@ -19,6 +19,8 @@
> RandomPool::RandomPool()
>        : m_pCipher(new AES::Encryption), m_keySet(false)
> {
> +       memset(m_key, 0, m_key.size());
> +       memset(m_seed, 0, m_seed.SizeInBytes());
> }
>
> void RandomPool::IncorporateEntropy(const byte *input, size_t length)
>
>