[Rd] r-project.org SSL certificate issues

peter dalgaard pd@|gd @end|ng |rom gm@||@com
Wed Jun 10 01:39:48 CEST 2020

Yes and no... At least as I understand it (Disclaimer: There are things I am pretty sure that I don't understand properly, somewhere in the Bermuda triangle beween CA bundles, TLS protocols, and Server-side settings), there are two sided to this: 

One is that various *.r-project.org servers got hit by a fumble where a higher-up certificate in the chain of trust expired before the *.r-project.org one. This was fixed by changing the certificate chain on each server.

The other side is that this situation hit Mac users harder than others, because Apple's LibreSSL doesn't have the same feature that openSSL has to detect a secondary chain of trust when the primary one expired. This was not unique to R - svn also failed from the command line - but it did affect download.file() inside R. 

The upshot is that there might be 3rd party servers with a similar certificate setup which have not been updated like *.r-project.org. This is not too unlikely since web browsers do not have trouble accessing them, and the whole matter may go undetected. For such servers, download.file() would still fail.  

I.e., there is a case to be made that we might want to link openSSL rather than LibreSSL.  On the other hand, I gather that newer versions of LibreSSL contain the relevant protocol upgrade, so maybe one can just wait for Apple to update it. Or maybe we do want to link R against openSSL, but almost certainly not for a hotfix release.


> On 10 Jun 2020, at 00:50 , Simon Urbanek <simon.urbanek using R-project.org> wrote:
> To be clear, this not an issue in the libraries nor R, the certificates on the server were simply wrong. So, no, this has nothing to do with R.
> Cheers,
> Simon
>> On Jun 10, 2020, at 10:45 AM, Henrik Bengtsson <henrik.bengtsson using gmail.com> wrote:
>> Was this resolved upstream or is this something that R should/could
>> fix? If the latter, could this also go into the "emergency release" R
>> 4.0.2 that is scheduled for 2020-06-22?
>> My $.02
>> /Henrik
>> On Sun, May 31, 2020 at 8:13 AM Gábor Csárdi <csardi.gabor using gmail.com> wrote:
>>> Btw. it would be also possible to create a macOS R installer that
>>> embeds a static or dynamic libcurl with Secure Transport, instead of
>>> the Apple default LibreSSL.
>>> This might be too late for R 4.0.1, I don't know.
>>> Gabor
>>> On Sun, May 31, 2020 at 4:09 PM Gábor Csárdi <csardi.gabor using gmail.com> wrote:
>>>> On Sat, May 30, 2020 at 11:32 PM Gábor Csárdi <csardi.gabor using gmail.com> wrote:
>>>> [...]
>>>>> Btw. why does this affect openssl? That root cert was published in
>>>>> 2010, surely openssl should know about it? Maybe libcurl / openssl
>>>>> only uses the chain provided by the server? Without trying to use an
>>>>> alternate chain?
>>>> Yes, indeed it seems that old OpenSSL versions cannot handle
>>>> alternative certificate chains. This has been fixed in OpenSSL in
>>>> 2015, so modern Linux systems should be fine. However, macOS uses
>>>> LibreSSL, and LibreSSL never fixed this issue. E.g.
>>>> https://github.com/libressl-portable/portable/issues/595
>>>> r-project.org can be updated to send the new root certificate, which
>>>> will solve most of our problems, but we'll probably have issues with
>>>> other web sites that'll update slower or never.
>>>> FWIW I built macOS binaries for the curl package, using a static
>>>> libcurl and macOS Secure Transport, so these binaries does not have
>>>> this issue.
>>>> They are at https://files.r-hub.io/curl-macos-static and they can be
>>>> installed with
>>>> install.packages("curl", repos =
>>>> "https://files.r-hub.io/curl-macos-static", type = "binary")
>>>> They support R 3.2 and up, including R 4.1, and should work on all
>>>> macOS versions that the given R release supports.
>>>> Gabor
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Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
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