[Cryptography-dev] Low level API for Symmetric Encryption

[Alex Gaynor]

Another option is to compose them in the constructor: AES(keysize=256,
mode=GCM) or so.

Alex


On Wed, Aug 7, 2013 at 4:12 PM, Donald Stufft <donald at stufft.io> wrote:

>
> On Aug 7, 2013, at 6:32 PM, Jean-Paul Calderone <
> jean-paul at hybridcluster.com> wrote:
>
> > On 08/07/2013 06:16 PM, Donald Stufft wrote:
> >> So to kick things off I'd like to get AES-GCM exposed and figured it
> could be a good way to start the ball rolling for figuring out how we want
> to expose symmetric ciphers at the low level API.
> >>
> >> I'm thinking cryptography.primitives.aes which has classes named like
> AES128GCM, AES256CBC, etc. The obvious naming scheme being
> AlgorithmKeysizeMode.
> >>
> >>
> >
> > GCM (CBC, etc) is a mode of operation that is applicable to arbitrary
> > block ciphers.
> >
> > Why should it be tied to "AES128"?  Why wouldn't you GCM(AES128())?  If
> > you're talking about primitives, AES128 is more primitive than GCM on
> > AES128.  And GCM isn't specific to AES, so I don't see
> > cryptography.primitives.aes as the proper home for it.
> >
> > I hope these aren't questions with highly obvious answers.
>
> As far as I know (and I could be wrong? I don't know OpenSSL guts that
> well) OpenSSL doesn't do composition like that, in order to get AES-128-GCM
> you pass that in.
>
> Is there a way to access openssl where you're composing GCM with AES128?
> If not I think we'd be stuck do some sort of "combine variables of the
> classes AES128 and GCM to make the name AES-128-GCM to pass into openssl"
> thing which doesn't feel particularly clean to me?
>
>
> -----------------
> Donald Stufft
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> DCFA
>
>
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