[openssl-users] Stand alone AES-CTR module

Mike Mohr akihana at gmail.com
Tue May 12 03:59:16 UTC 2015

If you don't know about list comprehension in Python, you can simply
construct a list in a loop to get the job done.  The end result is the same
no matter which approach you take.

The same is not true for cryptography.  While Sec_Aficionado is quite
eloquent and makes several valid points, I think his overall argument does
not hold water.  I have audited the crypto implementations in a number of
open-source projects over the years found wide variance in their quality.
In one instance a popular piece of software included a feature which
claimed to encrypt its data using AES-256.  It turned out that the code
copied the user's password directly into the key buffer, either padding
with null bytes or truncating depending on the length.  The data was then
encrypted using AES-256 in ECB mode.  The software's primary purpose was
not cryptography, and it provided innovative and creative features
otherwise.  This type of bug is insidious, since it doesn't really protect
the data in any meaningful way and lulls its users into a false sense of

I am not advocating that the realm of information security be forever
relegated to a select few.  That is also dangerous, as Sec_Aficionado
correctly pointed out.  However, the study of cryptography should never be
undertaken without the guidance of an experienced practitioner.  I had the
extraordinary opportunity to study information security at university under
the guidance of an ex-NSA analyst.  I recognize that I am extremely lucky
to have had this chance, and that this kind of education is only available
to a select set of people worldwide.  I also don't have a solution to the
problem of training the next generation of cryptographers.  However, having
yet another potentially compromised AES implementation written by a novice
programmer is not something that I want to encourage.

On Mon, May 11, 2015 at 6:12 AM, Sec_Aficionado <secaficionado at gmail.com>

> While implementing one's own security and/or cryptography is certainly not
> advisable for a novice (or even advanced programmers), creating cipher
> implementations from scratch is probably one of the best ways to learn and
> understand the intricacies of the problem at hand.
> Learning about the pitfalls and advantages of the algorithms is key for a
> future security expert. Moreover, denying someone access to help on an open
> source project is antithetical to the OSS philosophy. How can anyone hope
> to understand code that by its very nature is cryptic and complex if
> there's no one willing to help disentangle, at least at a high level, the
> routines and functions?
> InfoSec is a black art today, but it needs to get out of that mode. After
> the last few years it is clear that unless we open up the understanding of
> these disciplines, we will be at the mercy of experts with hidden agendas.
> Only educated users can hope to make correct use of cryptography, or be
> able to choose the best application for their needs. As we know, even a
> robust cipher is useless if utilized for the wrong purpose or poorly
> configured. We can't turn away those with a genuine interest in learning
> how to use cryptography without dooming ourselves to continue with the
> status quo.
> I appeal to those of you who routinely share your knowledge and try to
> make a difference here, that you provide some guidance and not turn away
> people with basic questions like this one. These are the users who may
> become one day contributors. They should be nurtured and not shunned.
> OK, I'll get off my soapbox now. Have a great week everyone.
> On May 10, 2015, at 5:58 PM, Mike Mohr <akihana at gmail.com> wrote:
> The task of implementing AES should not be undertaken by a novice
> programmer.  Please save the world another heartbleed and pick something
> more in line with your skill level.
> On May 10, 2015 11:48 AM, "konstantinos Alexiou" <
> konstantinakos.a at gmail.com> wrote:
>> Dear Sirs,
>> I am new to C programming and i am trying to create an independent to
>> libraries source code for demonstration purposes for AES-CTR mode.Could i
>> have some help on doing that using the source code contained under
>> crypto/aes.
>> Thank you very much in advance.
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