Re: [saag] [TLS] Lessons learned from TLS 1.0 and TLS 1.1 deprecation

Daniel Migault <> Thu, 26 September 2019 13:51 UTC

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From: Daniel Migault <>
Date: Thu, 26 Sep 2019 09:50:57 -0400
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To: John Mattsson <>
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Subject: Re: [saag] [TLS] Lessons learned from TLS 1.0 and TLS 1.1 deprecation
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Thanks for raising this discussion John, we have been struggling with this
in curdle as well and ipsecme. This is also a topic that I believe would be
useful to improve the security.

One aspect is that some implementers go to the IANA pages and believe that
everything on the pages is acceptable. I believe that it would be worth
adding some status associated to the code points. Currently, in most cases
a reference is associated to the code point. In some cases, the reference
is the RFC or document creating that created the code point in other cases,
the reference could be the RFC that deprecates the code point. There is no
specific rules, and that is probably something that would worth being
clarified. That being clarified, I still believe that it could be useful to
have a some sort of indication like a column that indicates whether the
code point is deprecated or not. This may involve additional terminology
depending on the level of information needed.

Another aspect would be to have software automatically checking which are
the code points status. This would of course only solve one side of the
problem as a device may end up on becoming silent, but that is probably
what should occur to non maintained devices.


On Thu, Sep 26, 2019 at 8:18 AM John Mattsson <john.mattsson=>; wrote:

> Hi,
> Hopefully, we have learned some lessons from the TLS 1.0 and TLS 1.1
> deprecation. TLS 1.0 and TLS 1.1 are (to cite Martin Thomson) broken in a
> myriad subtle ways and should according to me optimally have been
> deprecated years ago.
> 3GPP mandated support of TLS 1.2 in Rel-13 (2015) but could at that time
> not forbid use of TLS 1.1 as that would potentially break interoperability
> with some Rel-12 nodes (that had TLS 1.2 as should support). The lesson
> 3GPP learned from this was the need to as early as possible mandate support
> of new protocol versions. With TLS 1.3, 3GPP took action early and TLS 1.3
> support was mandated for network nodes in Rel-15 (2018) and for mobile
> phones in Rel-16 (2019).
> At some point in time we will want to deprecate TLS 1.2. To enable that,
> TLS 1.3 support should be mandated or encouraged as much as possible. I
> would like to avoid a situation where we want to deprecate TLS 1.2 but
> realize that it cannot be done because some implementations only support
> TLS 1.2. How can IETF enable smoother and faster deprecations in the
> future? The browser industry has a decent track record of algorithm
> deprecation and I hope to soon see the following warning in my browser:
> “TLS 1.2 is obsolete. Enable TLS 1.3 or later.”
> Other industries have less stellar track records of algorithm deprecation.
> How can IETF be more pro-active regarding deprecations in the future? In
> the best of words, nobody should be surprised when IETF deprecates a
> protocol version or algorithm. NIST and similar organizations in other
> countries have the practice to long time in advance publish deadlines for
> security levels, algorithms, and protocol versions. Can the IETF do
> something similar, not just for TLS but in general? For TLS, there are
> several things to deprecate, in addition to MD5 and SHA-1, also PKCS1-v1_5,
> RSA-2048, 224-bit ECC, ffdhe2048, and non-recommended cipher suites (Static
> RSA, CBC, DH, NULL, etc.) should be deprecated in the future.
> Cheers,
> John
> _______________________________________________
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