Re: [TLS] Middlebox Security Protocol initial drafts

Eric Rescorla <> Fri, 13 April 2018 15:36 UTC

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From: Eric Rescorla <>
Date: Fri, 13 Apr 2018 08:36:07 -0700
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Subject: Re: [TLS] Middlebox Security Protocol initial drafts
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Hi Tony,

Thanks for forwarding these.

I haven't had time to give them a thorough review, but on a quick skim I
notice that this seems to be based on TLS 1.2 and to use a bunch of
algorithms we are trying to deprecate (e.g., CBC). Is there a reason not to
start with TLS 1.3 and more modern algorithms?


On Fri, Apr 13, 2018 at 8:07 AM, Tony Rutkowski <> wrote:

> As everyone is aware, the decision was taken
> within the IETF TLS community not to undertake
> work perceived to compromise TLS 1.3 and related
> protocols.  At the same time, there has been
> recognition that a considerable number of use
> cases exist where alternative transport, network
> and application layer implementations are
> necessary in both network infrastructures and data
> centres.
> The work on those alternative implementations has
> proceeded over a two year period in ETSI's Cyber
> Security Technical Committee (TC CYBER). In the
> spirit of some level of collaboration between ETSI
> and the IETF community, as well as public
> transparency, CYBER is making available two draft
> parts of a Technical Specification called the
> Middlebox Security Protocol.  The motivation is to
> address one of the most difficult security
> challenges today: how to enable network operators
> and end-users to cooperate in managing encryption
> security for their applications.  The drafts are
> available at:
> Note that there are two problems being pursued
> here.  The Middlebox Security Protocol enables the
> existence of a “smart proxy” where end-users can
> be potentially aware of a middlebox in their
> traffic stream (visibility) and control what that
> middlebox sees for different purposes
> (observability). The result allows for balancing
> privacy, network operations, and security for
> different applications. With the Protocol, both
> users and providers gain the ability to grant or
> restrict the permissions for visibility and
> observability.
> Part 1 of the Middlebox Security Protocol
> specification defines the generic capabilities and
> security requirements. Additional parts define
> specific implementations in the form of profiles
> for different use cases that can be mapped to the
> Part 1 requirements.
> Part 2 provides a common profile for widespread
> network use known in the research community as
> mcTLS.  Included with Part 2 are a patch for a
> known vulnerability as well as an exemplar of use
> by Mobile Network Operators. Other profiles will
> be released over the coming months – especially
> one for data centre access control to meet the
> critical needs of enterprise network communities.
> These initial two draft specifications are
> relatively complete and stable, and derived from
> best-of-breed solutions drawn from extensive
> surveys and evaluation of the considerable
> published technical literature. However, this
> work is new, complex, and unique.
> In addition, TC CYBER is proactively sending the
> drafts to other industry standards bodies as well
> as holding a Hot Middlebox Workshop (12 June 2018)
> and Hackathon (12-13 June 2018), in Sophia-Antipolis
> France, where the coding community can seek to
> implement and hack a test implementation of Part 2.
> It is all open, and free.
> In addition to collaboration and comments on this list,
> comments are also solicited at
> --tony r