Re: [TLS] More clarity on resumption and session hash

David Benjamin <davidben@chromium.org> Fri, 29 May 2015 18:14 UTC

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From: David Benjamin <davidben@chromium.org>
Date: Fri, 29 May 2015 18:14:29 +0000
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To: "Salz, Rich" <rsalz@akamai.com>, Eric Rescorla <ekr@rtfm.com>, Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: [TLS] More clarity on resumption and session hash
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On Fri, May 29, 2015 at 2:09 PM Salz, Rich <rsalz@akamai.com> wrote:

> > I poked a bit more and I was mistaken about OpenSSL's d2i_SSL_SESSION
> behavior: Although it does ignore the structure version, it will fail the
> parse if it sees elements at the end of the structure it doesn't understand.
>
> We'd like to change this.  Allow applications to append their own data to
> a session is very useful.
>
> (We is probably my employer submitting patches to OpenSSL which someone on
> the dev team like me will review.()
>

This is somewhat tangential, but this seems a bad idea. Having applications
squat the same namespace of tag numbers as OpenSSL will break when OpenSSL
internally adds more fields to the end. If you want applications-specific
data in the session, either the application should serialize and
deserialize a wrapper structure that happens to contain a serialized
SSL_SESSION, or explicitly introduce an OCTET STRING hole to stuff opaque
application-specific data into.

David