Re: [TLS] network-based security solution use cases

Stephen Farrell <> Wed, 08 November 2017 00:08 UTC

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To: "Nancy Cam-Winget (ncamwing)" <>, "Flemming Andreasen (fandreas)" <>, Florian Weimer <>
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From: Stephen Farrell <>
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Date: Wed, 8 Nov 2017 00:08:52 +0000
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Subject: Re: [TLS] network-based security solution use cases
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On 07/11/17 23:53, Nancy Cam-Winget (ncamwing) wrote:
> Hi Stephen, Adding to Flemming’s comment,  finding “exact quotes”
> will be difficult 

I'm sorry but when making a claim that such and such a regulation
*requires* breaking TLS then you really do need to be that precise.

> as their intent is really not to break things but
> rather want to ensure that inspection and oversight is available to
> affect guards/protections within an (enterprise/data center)
> infrastructure.   That said, PCI and other regulations will have a
> lot of documents that one has to go through….one that kind-of calls
> explicitly to the use of packet inspection, firewalling and such is
> in:

The first mention of TLS there talks about protecting administrator
passwords via TLS. That totally argues against deployment of any kind
of MitM infrastructure.

> It is an assessment questionnaire for vendors to evaluate their
> compliance, the requirements speak to securing the network and
> systems including firewalls, DMZs and the ability to do packet
> inspection.

Please point me at the specific text. Given you added PCI-DSS to
your document I would assume you did the work already. If not,
that's a bit odd.


> Thanks, Nancy
> On 11/7/17, 3:27 PM, "Flemming Andreasen (fandreas)"
> <>; wrote:
> Thanks for taking an initial look at the document Stephen - please
> see below for responses so far
> On 11/7/17 4:13 AM, Stephen Farrell wrote:
>> Hiya,
>> On 07/11/17 02:48, Flemming Andreasen wrote:
>>> We didn't draw any particular line, but the use case scenarios
>>> that we tried to highlight are those related to overall security
>>> and regulatory requirements (including public sector)
>> I had a quick look at the draft (will try read properly en-route
>> to ietf-100) and I followed the reference to [1] but that only lead
>> to a forest of documents in which I didn't find any reference to
>> breaking TLS so far at least. Can you provide an explicit pointer
>> to the exact document on which that claim is based?
> For NERC, you can look under  "(CIP) Critital Infrastructure 
> Protection". CIP-005-5 for example covers the electronic security 
> perimeter, which has a couple of relevant requirements and associated
> text:
> To be clear though, the document does not specifically call out
> breaking TLS, but it does clearly call out the need to detect
> malicious inbound and outbound communications by leveraging an
> "Electronic Access Point" (e.g. IDS/IPS) to enforce the Electronic
> Security Perimeter.
>> I'd also claim that your reference to PCI-DSS is misleading, as
>> that same spec also explicitly calls for there to be good key
>> management specifically including minimising the number of copies
>> of keys, so at most, one might be able to claim that PCI-DSS is ok
>> with people who break TLS in a nod-and-a-wink manner. But if you do
>> have a real quote from PCI-DSS that calls for breaking TLS then
>> please do also send that (it's been asked for a bunch of times
>> without any answer being provided so far).
> I will need to look more closely for such a quote - if anybody else 
> knows of one, please chime in as well.
> Thanks
> -- Flemming
>> Thanks, S.
>> [1]