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

[David von Oheimb <it@xxxxxxxxxxxxx>]

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:20010030000000052aeb9adc1ce8b1ec

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.