Why does OpenSSL report google's certificate is "self-signed"?
Jan Just Keijser
janjust at nikhef.nl
Thu Apr 1 08:40:27 UTC 2021
On 01/04/21 09:49, Dr Paul Dale wrote:
> Perhaps ask Qualys to answer your concerns directly? They must have a
> reason for including this warning.
oh, I am not particularly /concerned/ about it - it's just that I
noticed Qualys spits out this warning whenever I do include the root
anchor, without bothering to tell me *why*. A search points me to this
which says it is harmless to include the root anchor, except that it
will increase your site's latency due to a (slightly) larger TLS handshake.
JJK / Jan Just Keijser
> On 1/4/21 5:43 pm, Jan Just Keijser wrote:
>> On 31/03/21 19:43, Michael Wojcik wrote:
>>>> From: openssl-users<openssl-users-bounces at openssl.org> On Behalf Of Viktor
>>>> Sent: Wednesday, 31 March, 2021 10:31
>>>> To:openssl-users at openssl.org
>>>> Subject: Re: Why does OpenSSL report google's certificate is "self-signed"?
>>>> It looks like Google includes a self-signed root CA in the wire
>>>> certificate chain, and if no match is found in the trust store,
>>>> you'll get the reported error.
>>> What do people think about this practice of including the root in the chain?
>>> As far as I can see, neither PKIX (RFC 5280) nor the CA/BF Baseline Requirements say anything about the practice, though I may have missed something. I had a vague memory that some standard or "best practice" guideline somewhere said the server should send the chain up to but not including the root, but I don't know what that might have been.
>>> On the one hand, including the root doesn't help with path validation: either some certificate along the chain is a trust anchor already, in which case there's no need to include the root; or it isn't, in which case the peer has no reason to trust the chain.
>>> On the other, it's useful for debugging, and perhaps for quickly finding whether the highest intermediate in the chain is signed by a trusted root if that intermediate is missing an AKID (though we'd hope that isn't the case).
>>> I can also see an application deferring trust to the user in this case: "this chain ends in this root, which you don't currently trust, but maybe you'd like to add it?". Which doesn't seem like a great plan either -- and PKIX says trust anchors should be added using a trustworthy out-of-band procedure, which this is not -- but I suppose it's a conceivable use case.
>> The only thing I'd like to add to this is that whenever I *do*
>> include the root anchor in a website and run Qualys' ssllabs test on
>> it, I get a (minor) warning:
>> Additional Certificates (if supplied)
>> Certificates provided 3 (5051 bytes)
>> *Chain issues Contains anchor*
>> Unfortunately their documentation does not state *why* they print out
>> this warning or why it would be bad, but I normally remove the trust
>> anchor from the webserver certificate chain nevertheless. It could
>> very well be that I'm not the only web admin that follows their
>> advice in this respect.
>> JJK / Jan Just Keijser
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