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Re: Review of draft-mm-wg-effect-encrypt-09
2017-04-13 00:59:14
Hello,
On Mon, Apr 10, 2017 at 11:54 PM, Kathleen Moriarty
<kathleen(_dot_)moriarty(_dot_)ietf(_at_)gmail(_dot_)com> wrote:
Hi Martin,
We went through your comments one more time to make sure any
technical/substantive comments are addressed. Please see the
discussion inline.
On Mon, Apr 10, 2017 at 5:05 PM, Martin Thomson
<martin(_dot_)thomson(_at_)gmail(_dot_)com> wrote:
I most certainly reviewed 09. I haven't reviewed the diff. I doubt that it
would change my opinion on the macro - level problems.
My mistake, I thought the acronym you corrected was in version 9.
On 8 Apr. 2017 3:34 am, "Kathleen Moriarty"
<kathleen(_dot_)moriarty(_dot_)ietf(_at_)gmail(_dot_)com> wrote:
Hello Martin,
Thanks for your review. It seems that you have read version 8 or
earlier and not the current version, 9, from some of your suggestions
that have been corrected already. Your review also reads to me that
additional context setting may help, but please note that some context
setting was improved in version 9. We re-arranged some of the
sections per IESG review recommendations in the latest version as
well.
Perhaps you have additional language suggestions for context setting?
We have updated version 11 with new context setting text that
hopefully addresses your major concerns in tone setting for the rest
of the document.
The abstract states:
Increased use of encryption impacts operations for security and
network management causing a shift in how these functions are
performed. In some cases, new methods to both monitor and protect
data will evolve. In other cases, the ability to monitor and
troubleshoot could be eliminated. This draft includes a collection
of current security and network management functions that may be
impacted by the shift to increased use of encryption. This draft
does not attempt to solve these problems, but rather document the
current state to assist in the development of alternate options to
achieve the intended purpose of the documented practices.
which is repeated again in the introduction, but slightly reworded.
The introduction also includes statements on the existing publications
related to encryption and I read them as not having any bias, but
rather supporting the existing documents that also had consensus.
A couple of comments and one question inline.
On Thu, Apr 6, 2017 at 11:24 PM, Martin Thomson
<martin(_dot_)thomson(_at_)gmail(_dot_)com> wrote:
Draft: draft-mm-wg-effect-encrypt-09
Date: 2017-04-07
Overall
This document is unfocused and unclear in its intent. It is filled with
unsubstantiated claims, misleading statements, bias, and implied
recommendations
for bad practices. I would oppose its publication in the current form.
Furthermore, I don't believe that small scale or editorial changes would
be
sufficient to correct these problems.
Aside from weakening its utility and/or arguments, the lack of focus will
allow
this document to be abused in various ways. For instance, it might imply
IETF
endorsement of the practices described in the document. Given that the
IETF has
published positions that in some cases reject these practices, this
document
needs to be very precise with its claims. In its current form, it is not
nearly
careful enough.
This paragraph is all speculation about an unfortunate future.
We could speculate that the operator, security and app communities
come together to work out solutions after reading this doc,
which is part of our intent.
If this document is going to be published as an RFC, then it needs to be
very
clear about its intent and its position - or lack thereof - toward these
practices. It might be possible to say that these practices were employed
in
networks in the past and that encryption is reducing the viability of
those
practices. A value-neutral statement like that might be acceptable as
long as
it were framed carefully.
The document conveys that message everywhere. The words contributed were
changed in many places to remove any implication that the current practices
are "requirements" or even "needs".
The abstract and introduction contain value neutral statements like
what you are suggesting already. We actually say the practices may be
eliminated, going further than your request as that may be the case.
The only change I could see in the abstract would be the following:
The abstract has been updated further to ensure the context is set and
shows how the document further supports the goals of RFC7258.
Hopefully this is a helpful update for you.
Increased use of encryption impacts operations for security and
network management causing a shift in how these functions are
performed. In some cases, new methods to both monitor and protect
data will evolve. In other cases, the ability to monitor and
troubleshoot could be eliminated. This draft includes a collection
of current security and network management functions that may be
impacted by the shift to increased use of encryption and encryption
that is designed prevent interception. This draft
does not attempt to solve these problems, but rather document the
current state to assist in the development of alternate options to
achieve the intended purpose of the documented practices when possible.
Do you have additional suggestions? Or is the phrasing read
differently than we intended by stating functions may be eliminated?
We thought that was very clear to your points.
What is problematic is the implicit argument that is presented. This
document
could easily be construed as the IETF legitimizing these practices. This
includes things on which the IETF has published statements (see for
example RFC
2804).
See the abstract and introduction and summary.
This steps firmly into to sticky mess that is the politics of encryption
policy.
If the IETF is going to make a political statement with this document,
then that
statement needs to be a lot better than this.
The intent of this document is to help operators as these changes
continue. It is to make sure we are not ignoring the impact of the
changes the IETF has with our decision (which are supported in this
document). This document is intended to assist operators. By
explaining the functions being performed, some have already been
provided alternate methods to achieve their goals. We have also
received quite a bit of positive feedback from operators - that this
document helped them come back to the discussion and to approach a
world with more encryption or sessions that can't be intercepted (TLS
1.3, TCPinc, QUIC, etc.).
Furthermore, any statement needs to be consistent with previous
statements,
where in this case that primarily means RFC 7258. Right now it reads as
an
attempt to dilute RFC 7258.
Not at all.
It does not read that way to many people who strongly support RFC
7258, including Stephen who was our sponsoring AD (and was for 7258).
Can you give specific sections where it sounds like we are weakening
RFC 7258 so we can change that specific wording?
If this document were more clearly formulated as an even-handed treatment
of
what happens today - without judgment - then it could be useful. Here the
model
of RFC 7754 is a good one. It describes the different facets of a use
case,
then the different practices that might be employed to achieve that goal.
For
each practice the pros, cons, and technical limitations are covered with
an eye
to all involved parties.
Version 8 to 9 had some edits to remove statements with used terms
like 'need'. We may have missed a couple, we'll check the ones you
pointed out. There are also numerous statements that are explicitly
in support of RFC7258. These are in the abstract, introduction,
summary and sprinkled throughout the document.
Apparently, RFC 7754 goes further than our scope. We are not describing:
"... the different practices that might be employed to achieve that goal."
The Real Purpose of this Document
I think that this is the real question that this document wants to ask is:
In a world where we are forced to defend against pervasive monitoring
by
motivated and malicious actors, can we find a role for less pervasive
monitoring by well-intentioned entities?
The document aims to help operators by giving them a chance to discuss
the impact. It opens the
door to conversation so they can find new ways to achieve the same
goals (better performance for customers for instance or monitoring
services that have been requested - web content, DLP), which may mean
endpoint solutions are needed or filtering limited to hostnames for
now until other mechanisms are developed (likely at the application
layer).
For enterprises, application and host level solutions are
fine as many organizations have employees sign away their rights to
privacy. I would never check FaceBook from work for instance or
access any site of a personal nature. This is why we broke out the
sections by the type of network or SP, their options are different
with and without encryption.
QUESTION: Would it help to add some text like the first paragraph into
the introduction? - This document aims to...
There is an interesting discussion to be had here, but I'm convinced after
my
review that this document is the wrong vehicle for that discussion.
RFCs are the vehicles the IETF has found most useful in talking to the world.
I'm
also
inclined to suggest that this is the wrong question to ask in the first
place.
We can't ignore the problems resulting from the changes, we the IETF
make, to improve privacy and security. While we agree it is a positive
thing to improve these functions, we (the IETF) should also help with
the wake we
leave in our path. Otherwise, we can't expect people to play along
with the protocol specifications the IETF publishes.
It's much more than an "interesting discussion" to many operators.
Some are required by law to use these practices to protect privacy.
There are many questions to ask, some of which have already been
answered. For example, RFC 7258 asked 'How can we deal with
pervasive monitoring' and answered it through the same IETF
consensus process this document has already gone through.
To the extent that we have the tools necessary to protect against
pervasive
monitoring, we have to accept that more-legitimate uses of monitoring are
collateral. Mostly, that's just a function of the limitations of the
imperfect
tools we have.
The value in this document is in the rather comprehensive collection of
use
cases. Sure, some we might not attribute much weight to, like
wiretapping.
Others are frankly frightening and not just in the Orwellian sense.
The problems that are implied by the current practices of network
operators is a
large vein of unexplored work for the community. Spending effort on
finding
better solutions to legitimate problems is worthwhile.
Right, so we started by documenting them *before* the collateral damage
appears.
We've added some additional statements in line with the goals of
RFC7258 balancing network management and PM mitigations.
In other words, the right question might be:
For each of these practices that we see today, are the use cases that
motivate them legitimate and how might be implement alternative
techniques
that properly respect privacy and security?
Yes, this is the point of the document and it's stated in several places.
Two- and Three- Party Interactions
A great many sections of the document are unclear about the relationships
between different actors. It seems like many of the activities describe,
which
are presented here as being beneficial, are performed by a third party
without
the consent or involvement of the two communicating peers. After all,
those are
the cases where encryption most often interferes.
As the draft says, some of the methods will be eliminated.
This wording has been updated to avoid unintended interpretations of that text.
The assertion that some benefit is accrued to communicating peers as a
result of
these actions is the constant subject of the text. I observe that in most
of
the cases listed in this document, the benefit is accrued primarily to the
third
party.
Operators by their nature have different privacy concerns than their end
users. Operators by their nature want to accrue benefits. This document
doesn't change the balance; instead, it tells them how to deal with privacy
that has already been applied. While we agree with your statement and think
it's important to build privacy and privacy options into IETF protocols,
operators often don't care, despite the many RFCs we have published
telling them that they should care. We still need to engage them so we can
have this discussion.
The "third party" is likely the only one receiving a trouble call,
and there is benefit for all parties when the trouble is cleared.
Clarity around the arguments that the document makes with respect to
benefits to
each of the involved parties is sorely lacking.
In addition to this, where benefits truly do accrue to communicating
peers,
technical options that don't rely on privacy-invasive techniques are
routinely
dismissed in an offhand fashion. In this way, any moral imprimatur
attributed
to the use case is used to justify the privacy-invasive method.
Without specific comments, the above are all subjective statements and
we have responded to them.
We have also made an effort to update text to clear up tone questions
where specific text has been called into question.
Document Structure
This document is very hard to read (and review). Probably my biggest
complaint
is that the sections are haphazardly organized. They contain a mixture of
use
cases (what does SP X want to do) and techniques (how do they do these
things).
Material is duplicated between sections. Sections cover 10 different use
cases
while talking about techniques, then other sections talk about different
techniques whiles talking about a scenario. This leads to a lot of
repetition.
There are three axes that this document contemplates:
- the techniques that are currently used in networks
- the use cases that motivate these techniques
- the deployment scenarios in which these use cases manifest
It would appear that the document attemps to start from the deployment
scenarios. However, this causes use cases and techniques to be mixed.
Judicious use of cross-referencing might have made this arrangement
tractable,
but there are virtually no cross references.
The above is stylistic in nature. We've already made changes to the
format to address specific comments in IESG review. A complete
re-write is not appropriate at this point in the draft lifecycle.
That's not the point of IESG review.
Section 1
I find the introduction of this document difficult to parse. I think that
what
it wants to say is pretty straightforward, but it manages this in quite an
obtuse way. Here's what I think that it is trying to say:
1. The IETF (and the larger community) has reacted to revelations of
pervasive
monitoring by increasing the use of encryption.
2. That has been somewhat successful.
3. More encryption has an impact on some practices that network operators
have
become accustomed to employing.
Expressed in this way, you can see how you could make a value-neutral
statement.
On the first, you can definitely make an argument based on the documents
that
the IETF have published. However, it is a mistake here in assuming that
the
IETF - or the revelations of global-scale surveillance - is directly
responsible
for the uptick in adoption of cryptographic protection for Internet
traffic.
The abstract is value neutral right now.
The abstract has been updated, please see version 11.
The increase or changes are not just about PM. We are making
TLS 1.3 so that it cannot be intercepted (I agree with this move of
course as we should make our protocols strong and adhere to
established IETF principles)? Or the efforts of TCPInc and
QUIC? We do directly affect the use of encryption and the types of
encryption that are deployed. We work with the vendor communities in
publishing deprecation drafts as well. All of these efforts got
additional energy from the PM work and that's a good thing. Events
trigger increases in security and it's fine to acknowledge that. The
introduction states:
In response to pervasive monitoring revelations and the IETF
consensus that Pervasive Monitoring is an Attack [RFC7258], efforts
are underway to increase encryption of Internet traffic. Session
encryption helps to prevent both passive and active attacks on
transport protocols;
We could change it to say:
In response to pervasive monitoring revelations and the IETF
consensus that Pervasive Monitoring is an Attack [RFC7258], efforts
are underway to improve and increase encryption of Internet traffic.
Session
encryption helps to prevent both passive and active attacks on
transport protocols;
The second sentence mentions passive and active attacks here as that
hits on the prevention of active attacks - improving session
encryption protocols helps with this.
update made.
This is something that the community as a whole has been working towards
for
many years; these trends predate the actions this draft focuses on. This
is
particularly true for the hosted provider cases in Section 3, where
business
motivations for protection are far stronger than any concerns over
government
surveillance. Yeah, that's a subjective view, but I'm just reviewing, I
don't
have to write a statement that will be labelled as having IETF consensus.
Section 3 already makes this point very clear (full text for the intro
to that section):
3. Encryption in Hosting SP Environments
Hosted environments have had varied requirements in the past for
encryption, with many businesses choosing to use these services
primarily for data and applications that are not business or privacy
sensitive. A shift prior to the revelations on surveillance/passive
monitoring began where businesses were asking for hosted environments
to provide higher levels of security so that additional applications
and service could be hosted externally. Businesses understanding the
threats of monitoring in hosted environments only increased that
pressure to provide more secure access and session encryption to
protect the management of hosted environments as well as for the data
and applications.
The immediate focus on opportunistic security is highly misleading,
especially
in the web case. The amount of opportunistically secured web traffic is
miniscule by global standards. Since Firefox is the only browser to
support OS
for the web, so adjust the following by market share:
<https://mzl.la/2oc46ch>.
You'll need to cite text that is leading you to this conclusion as I
don't read it as being specific to OS, rather that OS is explained so
operators understand it in the mix of encryption options.
I understand that mail is more often opportunistically secured, and you
will
hear the virtues of OS sung from the rooftops, but all evidence suggests
that
this is just a transitory state. Instant messaging is closer to the web
case,
with the trend toward strong protections that include authentication. Of
course, I don't believe that mail or instant messaging represent any
significant
traffic volume, so you need to be very careful about the nature of the
claims
that are being made. It has to be that the volume of mail has to be a
rounding
error when it comes to capacity planning for networks.
On the second point, when making claims about prevalence of encryption, I
would
advise caution when citing statistics. Here's the graph for the Mozilla
figures
that I think are being cited <https://mzl.la/2obZjrb>. Here's a different
graph
with a different number <https://mzl.la/2oc263J>. This highlights the
point
that statistics need to be carefully cited, because bare claims are
difficult to
assess. Methodology matters when it comes to these sorts of claims - are
we
talking proportions of packets, requests, flows, or something else?
Furthermore, the citations in the document are made more difficult to
assess by
being measured at very different times (where the two I cite here were
made at
roughly the same point in time).
For the Mozilla statistics, Richard Barnes had reviewed the text after
providing the statistic as he wanted to make sure it was stated
clearly raising the same concerns you do about statistics. Do you
have further text suggestions to clarify this statistic?
The statistics do support the notion that there is a significant amount of
encryption in use, but it would appear that the claim is that the amount
of
encryption is *increasing*. This is not an extraordinary claim, but no
evidence
is offered in support of the claim. It isn't a certain thing either.
From the
statistics that I have access to, there was a definite uptick in October
of
2015, but the rate appears to be stable since then.
It appears that the remainder of the document is intended to address the
third
of my points in some detail. That's a good structure in theory, but see
above.
I don't think that the "service provider" taxonomy works for this
document.
Based solely on the structure of the document, the only service provider
that
this document concerns itself with is the one who forwards the packets.
That
application service providers are involved as one of the endpoints is
relevant
in some cases, but not all. For that reason, I prefer "network operator"
and to
use specific terms like "mail host" or "web server" as appropriate to the
context.
Those are subjective comments, so we'll put those aside.
Section 2 (top section)
I like that the attacks on SMTP by network operators is highlighted here.
We tried to have balance and had other attacks by operators in
previous versions, but only articles that are not stable references
for them and were asked to remove them in AD review.
There's an implicit argument here that runs counter to established IETF
consensus.
Some methods used by service providers are impacted by the use of
encryption
where middle boxes were in use to perform functions that range from
load
balancing techniques to monitoring for attacks or enabling "lawful
intercept", such that described in [ETSI101331] and [CALEA] in the US.
This fails to remain neutral.
The functions are impacted, so how would you suggest we word this
text? It doesn't endorse the functions, just says they are impacted.
We are open to suggested text. Similar to how we describe 'attacks'
by operators to break encryption or use RSA private keys. We do have
text in both directions on this and your review is complimentary of
the ones that fit your dialog, but are also not value neutral. Mind
you, I am constantly reviewing RFCs and making sure TLS best practices
are considered and questioning the use of deprecated crypto or not-yet
but should be deprecated crypto.
I read the text in the draft again and changed it as follows:
Some methods, used by service providers are impacted by the
use of encryption where middle boxes were in use to perform functions
that range from load balancing techniques to monitoring for attacks or
enabling "lawful intercept", such that described in ETSI101331
in the US. Only methods keeping with the goal of
balancing network management and PM mitigation in
RFC7258 should be considered in solution work resulting
from this document.
This implicitly makes a value-judgment
about
relative morality/acceptability/value of certain practices.
We have statements in both directions in the document as you point out
above with one of them.
What is
particularly insidious about this particular form is that it invites
interpretation that is subjectively coloured. For instance, as a non-EU
and
non-US citizen, I might consider the use of the particular lawful
intercept
techniques offensive; thus I might interpret this as a spectrum between
inoffensive to offensive. An employee of the US government might view
this
somewhat differently and interpret this as a scale between low-value to
high-value. I'm guessing here, but this is really just to highlight my
point
about care.
A more serious concern is this statement:
The loss of access to these fields may prompt undesirable security
practices
in order to gain access to the fields in unencrypted data flows.
But this is true and we've seen operators do things like prevent
STARTTLS. This isn't a good thing and we need to ack that this has
happened. We need to help operators figure out how they help users in
new ways and understand that some of the functions they perform
currently (TLS 1.2) won't work in the future.
This text got re-worded during AD review, I believe. The intent is to
say that this is not good - the practices are called out as
undesirable. How would you suggest it be re-phrased and we can check
back with Stephen to see if he agrees.
We changed the text slightly in a way that should help with your concern:
The loss of access to these fields, has in some cases,
prompted undesirable security practices in order to gain access to the
fields in unencrypted data flows.
I've read this argument before (see
https://queue.acm.org/detail.cfm?id=2508864
for the long form), and it might even have an element of truth to it.
However,
it's not a statement that I personally attribute any real credibility to,
and
nor do I think that it needs to be credited with any amount of
seriousness. I
certainly disagree with the IETF making any such statement. It says that
we are
collectively willing to bow in response to (anticipated) threats of
violence.
Prior to AD review, there was a reference in the text to the practices
being bad and stating that regulators and the media helped to correct
this behavior. The problem here may be the evolution of the
text and lack of reference now since we couldn't find a stable
reference. Do you have a wording suggestion?
<snip> questions and text addressed with Mirja's assistance.
Editorial:
* "pop" is a term of art that needs explanation.
Thanks for the nit corrections.
Section 2.2
I think that this sums the situation up reasonably well. It fails the
value-neutral test in a few ways though. As I understand the situation,
surveying operates at many levels. For accurate planning, models of
endpoint
behaviour are used to determine things like whether loss or congestion is
affecting throughput. Really good models require knowledge of what users
are
attempting to do and the applications they are using (as mentioned, things
like
browser version matter in these models). For instance, it isn't enough to
understand that the user is trying to receive 720p video, you also have to
know
that a 4k stream for the same content is available.
Sure, that's why we broke the draft down by operator type. Some
functions are shifting and the responsibilities for operators will
shift with these changes.
The degree to which these models are privacy-invasive is not even
acknowledged.
Suggest text please. The abstract and intro were meant to set the
context for the document. Some of the functions will be eliminated -
and that's fine, it is what it is, but operators need to adapt and
deal with the change. We should help them so we all get to a better
place with improved privacy for users and increased security. By not
helping them, we do not get closer to solving these problems.
Try to consider the operators perspective here. They are used to knowing
what SI has been exposed by knowing video format
or browser type that has been in the clear for years. Understanding
the practices
helps make it possible for apps/ops/security/transport to come together to
reach better solutions.
Nit: Did you realize that "well-intentioned" is a euphemism? I'd expect
that
subtlety to be lost on many readers though.
removed.
Section 2.3.1
I find this sad, even if I can recognize the truth of it:
A monitoring system could easily identify a specific browser,
and by correlating other information, identify a specific user.
As a browser vendor, we don't consider this to be a feature, it's a bug.
Section 2.3.2.1
This is a strange section under which to put caching. Caching is a use
case
akin to compression. I don't see it as belonging to the class of things
that
rely on DPI. You just intermediate the cleartext HTTP in the way that RFC
7230
recognizes. Note that RFC 7230 explicitly does not endorse the practice
of
transparent proxying for a range of reasons, not the least of which is the
complete lack of transparency (yep).
This was organized per IESG review.
Section 2.3.2.2
Again, it's strange to see differential treatment under DPI. I was fairly
sure
that fingerprinting was used here as well.
Section 2.4
This section doesn't even attempt to recognize that applications are much
better
now at scaling content to suit the device on which that content is
intended to
be consumed. It should.
The reason for that is that there has been a useful dialog between application
designers and network providers over time, beginning with app designers
saying "what do you mean the network has errors and delay? this works
fine in my lab...". The contributors viewed that as well understood
and far back
in time, so not necessary to mention.
If you think there should be text to this point, please suggest some.
This section should not represent compression as an unmitigated good. I'm
told
that significant damage can be done to video streams by "well-intentioned"
compression middleboxes.
Please suggest text.
Yet again I see a call back to the implicit threat of violence in "they
will
adopt undesirable security practices". Statements in that form have no
place in
IETF RFCs.
This was edited text per review and agreed upon (I think in the AD
review). Suggest alternate
text and we'll go back to the other person.
Section 2.5
This mentions RFC 7754 then blithely ignores its primary conclusion.
Generally,
The treatment in RFC 7754 of this subject is more even-handed.
The use of particular examples (betting, gambling, dating) shows cultural
bias.
subjective review again, but 7754 cites examples too.
Jargon warning: "core network", "the mobile network" ("the"?)
Section 2.5.2
This type of granular filtering could occur at the endpoint, however
the
ability to efficiently provide this as a service without new efficient
management solutions for end point solutions impacts providers.
The initial premise here (up to the first comma) is the conclusion of RFC
7754.
I disagree with the conclusion, and I suspect so does RFC 7754. In
scenarios
where this matters, endpoints are routinely managed centrally. The range
of
options for this sort of management are plentiful and diverse.
Sure, but there is an impact and it's okay to ack that and assist with
these alternate options. If you have text to suggest, please do so.
Section 2.5.3
This describes a captive portal, which in the case where the service
provider
has a relationship with their customers, seems like a poor solution. See
the
CAPPORT working group for ways in which people are actually working on a
solution to this problem.
Section 2.6
The capitalization of section headings is inconsistent here (and
throughout).
Section 2.6.1
Isn't this a duplicate of Section 2.1?
Section 2.6.2
I can't parse this statement:
Approved access to a network is a prerequisite to requests for Internet
traffic - hence network access, including any authentication and
authorization, is not impacted by encryption.
And then we get into zero rating, which is a hot-button topic. No
acknowledgment given to the sensitivities on the subject, or even a
superficial
exploration of the technical options that are available.
Please suggest text. This was updated in IESG review.
This text references a non-existent Appendix.
Fixed. It's section 7 now.
Section 2.6.5
This paragraph is strange. It starts by describing what appears to be use
cases
(are those scare quotes?). It finishes by implying that these are attacks
on
privacy (which they are).
What is "Non-Customer Proprietary Network Information"? I hope that this
isn't
an attempt to somehow privilege the information so that it seems less than
privacy-invasive.
Section 2.7
This is one of the areas that is most legitimately affected by increased
adoption of encryption. I have no doubt that having detailed information
about
the application and its use makes the process of troubleshooting easier.
This is the first mention in the document of network-based optimization.
Was
the section describing that cut from an earlier draft?
The use of websockets as a primary example is an odd one. It's just not
that
common. For reference, we see >20% failure rates on encrypted websockets
and
50% failures in the clear; no one in their right mind would rely on
websockets.
If the point is that HTTP is carrying more traffic (see
http://conferences.sigcomm.org/hotnets/2010/papers/a6-popa.pdf) saying
just that
would be more effective.
"in their right mind" . That isn't helpful. Operators submitted text
to explain what they are doing and how it's impacted. How about
proposing text to help in that vein.
Section 3
It would help if "hosted environments" was defined before diving in.
Section 3.1
The paragraph on DLP is ironically amusing. Encryption exists to prevent
private information leakage, but the assertion here is that encryption is
hampering DLP attempts.
It's true that protection of intellectual property is an important
business
goal, but this handling suggests an architecture that I'm fairly sure is
counter
to established wisdom (see "SSL added and removed here :-)":
https://www.washingtonpost.com/rf/image_404h/2010-2019/WashingtonPost/2013/10/30/Local/Images/GOOGLE-CLOUD-EXPLOITATION1383148810.jpg).
Worse, this casually dismisses a model that is actually more likely to
work.
Malware encrypts too (https://arxiv.org/abs/1607.01639).
The section talks about the end points being the better place for this
already.
Section 3.1.1
Who is the customer here?
Why does the hosting provider need to monitor access? They have the
ability to
limit accesses, but this is suggesting that what happens within the
envelope of
what they permit is important for them to know. I'd be surprised if you
could
show that this is true. Hosting providers - in my experience - value
their
ongoing business and would not jeapardize it by snooping on their
customers.
It's different if the customer opts in to a security service, but that
demonstrates a cooperative situation, where the rest of this document is
largely
concerned with adversarial uses of encryption.
This is describing the cooperative scenario. The service is hosted,
so maybe the definition of hosted would have helped you.
Section 3.1.2
This is another example where the organization of the document could
be improved.
Again with the "SSL added and removed here :-)" recommendation. PCI don't
permit that for good reason.
I don't read the following text in this section as a recommendation or
endorsement. Is there a tweak you think that should be made as I'm
not seeing the problem your describing. This is just describing what
they do and stating that it will be impacted and then the truth that
the functions may no longer be possible - not stating that it is good
or bad, just the fact that it won't be possible.
The use of tools that
perform SSL/TLS decryption are impacted by the increased use of
encryption that prevents interception. Alternate methods to acheive
the goals of these functions may be necessary and in some cases, the
functions may no longer persist in a pervasively encrypted Internet.
Section 3.2.1
I don't believe that monitoring of these types of application require
cleartext
access. There are two parties involved: the provider of the application
and the
user of it. The provider has most of the power here and can theoretically
design the system to allow whatever level of access they require. To the
extent
that the user needs protection from the application provider, that is a
matter
of negotiation between them.
I don't see how the adversarial three-party situation presented in the
rest of
the document applies in this situation.
Sure, there is a shift in how many functions will be performed
happening and this is documenting that shift. Much moves to the
application. We are helping to document the changes.
Section 3.2.2
No real mention of the effect of encryption here, or is this just saying
that
there is no issue here?
I don't see the point of the PGP/Dark Mail paragraph. I'd be leery of the
IETF
saying things like "PGP may be a front runner" though.
This was added per EKR in IESG review.
Section 3.3
There's certainly a lot of detail here, but I had a really hard time
extracting
value from this section. I can't see how data storage is fundamentally
different to the general case of an application provider.
They figured out how to increase encryption and manage their hosted
environments. There were adjustments made and they've been
successful.
Section 4.1.1
I appreciate the recognition that endpoint-based techniques work. The
implication that this isn't the obvious solution, much less so.
This isn't a technical comment, but we'll revisit the text to see if a
wording change can help.
Section 4.1.2
I'm confused about the purpose of this section. This seems to be talking
about
the sort of network-based methodologies an application provider might
employ to
ensure that their application is working as intended. Why would the
application
provider not have access to detailed logging and usage metrics?
The problem cited to us is that logging is sorely lacking. This needs
to be pointed out and fixed as it is too much for the operator to deal
with given the large number of applications running in their
environments.
As an aside, I skimmed through ietf-ippm-6man-pdm-option, since it is
cited no
fewer than three times in the same paragraph. It makes some fairly bold
claims
about its effect on privacy that I don't believe will hold up to analysis.
Section 4.1.3.1
This section correctly identifies the issue as one of shortcomings in
logging,
not increased use of encryption.
Right, a key point in this document - other methods will have to be
used and an obvious one is logging. However, logging needs to improve
for that to be possible.
I would have stopped there, but the section persists and ultimately
references
RFC 7974, which is widely recognized as a monstrously bad idea (the IESG
note is
fairly clear on this point).
Thanks for catching that. We can drop this text.
dropped.
Section 4.1.3.2
"HTTP/2", not "HTTP2".
Fixed.
I don't see how this section belongs in this document. The 1:1
correlation
between actions and flows in HTTP was a mistake of the 1980s that we've
spent a
lot of time on correcting (sometimes unsuccessfully, see pipelining).
Section 4.1.3.3
It's not a "service call" it's just a request.
Section 4.2
If the inclusion of a reference to RFC 7457 is to support a claim that TLS
is
attacked, that's sailing far too close to an endorsement of attacks than I
am
comfortable with. However, I don't believe that any of the listed attacks
remain viable in modern applications. What is most often the case is that
a
trust anchor is installed on enterprise users' machines and new
certificates are
minted as needed. In other words, the host that is accessing the HTTPS
site is
owned by the enterprise and modified so that it can comply with its
policies.
When you recommend attack like this (to be clear, I would oppose
publication of
text that does this), you need to acknowledge the downsides.
By use of the word, attack, this is not a recommended method. It's
also not in line with the goals of RFC7258, so it's just a practice
that's documented. Not one that is endorsed (none are).
For example,
MitM
devices routinely break connections, they hide the true security status of
communications from endpoints and users, they frequently implement weaker
versions of protocols, they often don't include the same degree of rigor
in
things like certificate validation, and probably many more things that I
can't
casually list off the cuff.
Please suggest text.
The discussion of caching here warrants a new section.
Section 5.1
s/effect/affect
Thanks, we'll fix this.
No complaint here, just an advertisement for technical solutions that
aren't
affected by increases in encryption. Good, though I'm not sure if the
section
meets the document's criteria for inclusion.
Section 5.3
No cititation for APWG. Not an IETF working group from what I can see.
We'll add that, thanks.
Added reference.
There's a presumption here that administrators need to perform these
tasks. Why
can't endpoints do this? It would certainly be a whole lot less invasive
that
way. Take a look at how browsers implement checks for "bad" sites (which
include phishing sites). These methods have some fairly significant
privacy
safeguards without compromising on performance.
A lot will move to the endpoints, but things like logging need to
improve and we need to get application developers to do a better job
so that there is no reason for someone to want to try to intercept
traffic for troubleshooting. Operators see this as an insurmountable
problem. We need to help.
Section 5.5
See my comment about about endpoint-based methods.
Already agree with this point.
Section 5.6
I believe that the spoofed source address problem is not relevant to this
document. It's a fairly well understood problem. That said, if we could
wave a
magic wand and get BCP 38 deployed, that might be nice.
Section 6.1
As this says, it's fairly well understood that - for HTTP - SNI is used.
The
point that it is optional is interesting, but doesn't deserve the amount
of
attention this section devotes to it. The clients that don't include SNI
are in
a diminishing minority.
Text was aded per EKR's review.
That said, this doesn't pay any attention to another feature in HTTP/2:
connection coalescing.
Please suggest text if this should be included.
Section 6.2
ALPN will be encrypted in TLS 1.3.
Noted. Thanks.
Section 6.3
This reads as a invitation to perform traffic analysis (a statement that I
oppose). Note that we have added padding to most recent protocols (HTTP/2
and
TLS 1.3 in particular) to give endpoints the ability to resist this sort
of
attack.
Note that block ciphers can add ~240 octets of discretionary padding per
record.
That can be pretty effective if you are careful.
I believe this text was added through the IESG review. I don't see
the problem with the text you are citing, so could you suggest
alternate text?
Section 7
This section is duplicative of much of the rest of the document. I
realize that
editing is hard, but see my earlier comments about structure.
This text was the appendix, but moved to section 7 per IESG review and
discuss. It was the mobile operator view.
It's obvious that this section is about QUIC. That shows in several ways.
It's
nice how it doesn't say so out loud, but it leaks through in several
confusing
ways. See below.
Section 7.1
This section is purportedly about encrypted ACKs, which won't happen until
we
get to QUIC. But the points regarding proxies (b, c, d) are not prevented
by
encrypted ACKs, they are prevented by encryption more generally. Point e
is
defeated by integrity protection of ACKs, not confidentiality protection.
I hope that the IETF never publishes draft-dolson-plus-middlebox-benefits;
it
makes claims about the benefits of specific solutions for different use
cases
with the goal of justifying those solutions. At the same time, it fails
to
recognize the existence of alternative, often superior, solutions for
those use
cases. In other words, it has many of the same issues as this document.
I think this is an early document and expect it will get some
revision. This was added into our document per Mirja's IESG review.
They are documenting middle boxes that use 5-tuples. That point isn't
clear until the summary. I provided some light feedback, but could
provide more to help them improve the document. I think it's fine to
document these things and then figure out how we can do better with
IETF agreed upon protocol design intentions (end-to-end and assisting
to improve user's privacy as well as the security of sessions.
FWIW, also be OK if draft-thomson-http-bc never went anywhere as well; I
don't
know how to close the gap between the privacy assurances I wish it had and
the
privacy weaknesses it has.
The phrase "trusted proxies" is a dangerously misleading phrase. The
concept of
trust is - particularly in this context - frequently abused.
That's why the quotes were there, but this has been re-phrased in 10 -
see the SecDir review.
Sections 7.2 and 7.3
I'd be interested in learning about the justification for these features
(again,
go back to my comment about to whom the benefit accrues, and I'd advise
caution
not to make the trickle-down economics mistake of using second-order
effects).
Personally, I'm not that sad that they are going to be negatively
affected.
Section 7.2, Point d seems to be saying something about a multiplexed
protocol,
not one that has an encrypted transport header (see above regarding QUIC).
All these points equally apply to HTTPS, which suggest that encrypted
transport
headers is not the issue (unless by transport we mean HTTP).
Again, section 7 was changed in IESG review and added into the body of
the document per Mirja's discuss since the mobile operator is
important to include.
Section 7.4
s/GPSR/GPRS/ ?
Fixed. I thought this was fixed in 9, hence me thinking you read the
wrong version.
Section 8
I generally agree with the first statement here, but after having read the
document, I could take away some very different views on what the
"problems at
hand" actually are. I suspect that different people will have very
different
takeaways.
The conclusion section of a document is not the right place to start
introducing
new information, particularly information relevant to RFC 2804.
Should we move this to the introduction perhaps to help with context setting?
Not sure where this is going:
Terrorists and criminals have been using encryption for many years.
Because it's disconnected from the remainder of the paragraph. If you are
going
to invoke the T-word, you had better have a strong argument to make. On
the
final sentence of that paragraph, the subject ("This") is unclear.
Sure, the point was that their use of encryption is not a
justification argue any of the improvements to crypto for the general
population. Incident handlers know full well that encryption has been
in place for a long time by these users. Essentially, it's not an argument
that
hold muster.
The following sentence was added:
Changes to improve encryption or to deploy OS methods have little
impact on the detection of such activities as they already have access to
strong encryption.
--
Best regards,
Kathleen
--
Best regards,
Kathleen & Al
--
Best regards,
Kathleen
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