Setting subjectKeyIdentifiers and authorityKeyIdentifiers - Re: Solved! - Re: Setting Issuer Alternative Name

[David von Oheimb]

Argh, so you were not really after Issuer Alternative Names (which, like
SANs, are about entity names),
but after Authority Key Identifiers (which, like SKIDs, are about IDs
for key material)!
That's an entirely different thing.

As a general note,
it would have been helpful to have a look at the OpenSSL documentation
on how to set them up
before experimenting in trial-and-error mode and asking on a large
mailing list like this.
With OpenSSL 3.0 the documentation on certificate handling has been
improved significantly,
and some more improvements are in the pipeline for version 3.2.
So (at least meanwhile) it's worth consulting the man pages first.

Concerning the particular topic SKIDs and AKIDs, I had recently
written to this mailing list 
on Thu, 2023-04-27 at 05:22 +0200:

> Another advantage of using the OpenSSL 3.0+ apps is that they
> automatically add any needed/recommended 
> subject key identifier (SKID) and authority key identifier (AKID)
> extensions (while they are not needed for self-signed end-entity
> certs),
> without the need to use extension configuration files or CLI
> parameters such as -addext 'authorityKeyIdentifier = keyid:always'

 David

On Sun, 2023-05-14 at 19:52 -0400, Robert Moskowitz wrote:
> i asked a question about the whole aKID and sKID piece on the pkix
> list 
> and Peter Gutmann said something that I had lost track of in the
> weeds...
> 
> The content of keyid used in:
> 
> authorityKeyIdentifier = keyid
> 
> Is the sKID from the signing cert.  argh.
> 
> So going back to the hack that Viktor had given me to have control
> over 
> the Validity dates in my self-signed cert,,,,
> 
> I realized that was where the aKID was really coming from, and that
> cert 
> was generated before I worked out controlling sKID in the conf:
> 
> subjectKeyIdentifier = $ENV::DET
> 
> So go all the way back to start.
> 
> and Now I have my certs with the sKID and aKID I was trying to get.
> 
> Well there is 2+ days of struggle and distracting all of you from
> other 
> tasks!
> 
> Thank you Viktor for you time.
> 
> I can't directly control what is in aKID, as it is pulling aKID from
> the 
> signing cert.  Fix that and..
> 
> Bob
> 
> On 5/14/23 15:28, Robert Moskowitz wrote:
> > 
> > 
> > On 5/14/23 14:00, Viktor Dukhovni wrote:
> > > On Sun, May 14, 2023 at 12:44:48PM -0400, Robert Moskowitz wrote:
> > > 
> > > > I looked at that manpage and tried:
> > > > 
> > > > authorityKeyIdentifier =
> > > > otherName:1.3.27.16.2.1.1;BITSTR:20010030000000052aeb9adc1ce8b1e
> > > > c
> > > https://datatracker.ietf.org/doc/html/rfc5280#section-4.2.1.1
> > > 
> > >         AuthorityKeyIdentifier ::= SEQUENCE {
> > >            keyIdentifier             [0] KeyIdentifier OPTIONAL,
> > >            authorityCertIssuer       [1] GeneralNames OPTIONAL,
> > >            authorityCertSerialNumber [2] CertificateSerialNumber 
> > > OPTIONAL  }
> > > 
> > > You're trying to set the AKID to just the GeneralName, but it has
> > > to be
> > > a tagged sequence,
> > 
> > I did spend some time digging to get what a "tagged sequence" is let
> > alone represent  it but can't find it in 5280
> > 
> > >   and note that "authorityCertIssuer" is the name of
> > > the "grandparent" of the certificate in which the AKID appears,
> > > along
> > > with the authorityCertIssuer you'd need to provide the serial
> > > number
> > > of the parent certificate.
> > 
> > The two together seems only mandated in sec A.2.
> > 
> > I am not finding any discussion on authorityCertIssuer being that of
> > the "grandparent", can you point me to that?
> > 
> > > But as I mentioned before, I don't expect that support for names
> > > other
> > > than directory names in the AKID extension is particularly common.
> > 
> > Well I could put:
> > 
> > e.d.c.a.b.0.b.e.0.6.8.2.e.0.b.9.5.0.8.f.f.3.e.f.f.3.0.0.1.0.0.2.ip6.
> > arpa.
> > 
> > ? It will exist (we are for now doing this under driptesting.org as
> > it 
> > will be a bit of process to get 3.0.0.1.0.0.2.ip6.arpa. delegated).
> > 
> > But that is 73 bytes to show a 16 byte value.
> > 
> > > You're better off with just "keyIdentifier", liking the child cert
> > > to the key if of the parent cert.
> > 
> > I assume you mean:
> > 
> > authorityKeyIdentifier = keyid
> > 
> > and I can't see how to set keyid to 20010030000000052aeb9adc1ce8b1ec
> > 
> > I can control subjectKeyIdentifier like:
> > 
> > subjectKeyIdentifier = 20010030000000052aeb9adc1ce8b1ec
> > 
> >             X509v3 Subject Key Identifier:
> >                 20:01:00:30:00:00:00:05:2A:EB:9A:DC:1C:E8:B1:EC
> > 
> > Which is defined as:
> > 
> > SubjectKeyIdentifier ::= KeyIdentifier
> > 
> > 
> > I tried
> > 
> > authorityKeyIdentifier = keyid=20010030000000052aeb9adc1ce8b1ec
> > 
> > And get an error
> > 
> > authorityKeyIdentifier = keyid:20010030000000052aeb9adc1ce8b1ec
> > 
> > Just uses the keyid as is:
> > 
> >             X509v3 Authority Key Identifier:
> > 0F:4E:5E:54:C2:4F:80:9E:E5:79:CD:B4:14:9B:BF:EB:A8:57:CB:CA
> > 
> > 
> > 
> > > 
> > > Perhaps I should not have mentioned issuer SANs, you probably have
> > > no
> > > use for them.  Do use the appropriate data type in the EE SAN.
> > > 
> > 
> 
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