On 6/14/2010 10:50 PM, Nicholas Maniscalco wrote:
> William A. Rowe Jr. wrote:
>> On 6/14/2010 7:59 PM, Nicholas Maniscalco wrote:
>>> Is using OpenSSL built with the PURIFY flag considered "secure"?
>>> I ask because I came across this comment, in md_rand.c:
>>>
>>> #ifndef PURIFY /* purify complains */
>>>        /* DO NOT REMOVE THE FOLLOWING CALL TO MD_Update()! */
>>>        if (!MD_Update(&m,buf,j))
>>>            goto err;
>>>        /* We know that line may cause programs such as
>>>           purify and valgrind to complain about use of
>>>           uninitialized data.  */
>>> #endif
>>
>> The last time someone went by such nonsense[1], they created an entirely
>> exploitable set of keys on all debian/ubuntu-derived distributions.  Good
>> luck with that, and please let us know what you are maintaining, so that
>> we might avoid such distributions and products.
>>
>> [1] http://www.debian.org/security/2008/dsa-1571
> 
> Thanks, William.  I am familiar with the Debian issue.
> 
> The code I pasted above is from ssleay_rand_bytes.  Perhaps you were
> thinking I was talking about the call in ssleay_rand_add?  I am quite
> aware that removing the call from ssleay_rand_add is a very bad idea :)
> 
> Are you still of the opinion that an OpenSSL built with PURIFY is
> insecure?  David Schwartz, indicated otherwise in a similar thread I
> started a few weeks back (see his last sentence),
> 
> http://www.mail-archive.com/[email protected]/msg27732.html
> 
> I was satisfied with his answer until I saw the comment above, hence the
> new thread.  Again, I'm just trying to get a definitive answer on
> whether the PURIFY flag is considered secure.  Thanks.

That is a good question.  Sure seems incorrect, if anything.

#else
#warning Invalid randomization in md_rand.c when building with -DPURIFY!
#endif

would help alert builders to this trouble.
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