Dear Nicos, Sorry for the delay with my response.
On Fri, Sep 22, 2017 at 11:06 AM, Nikos Mavrogiannopoulos <n...@gnutls.org> wrote: > On Wed, Sep 20, 2017 at 3:21 PM, Dmitry Belyavsky <beld...@gmail.com> > wrote: > > Dear Nikos > > > > On Wed, Sep 13, 2017 at 9:39 AM, Nikos Mavrogiannopoulos < > n...@gnutls.org> > > wrote: > >> > >> > >> 4. How do you handle extensions to this format? > >> > >> Overall, why not use X.509 extensions to store such additional > >> constraints? We already (in the p11-kit trust store in Fedora/RHEL > >> systems) use the notion of stapled extensions to limit certificates > >> [0, 1] and seems quite a flexible approach. Have you considered that > >> path? > >> > >> regards, > >> Nikos > >> > >> [0]. > >> https://p11-glue.freedesktop.org/doc/storing-trust-policy/ > storing-trust-model.html > >> [1]. > >> http://nmav.gnutls.org/2016/06/restricting-scope-of-ca- > certificates.html > > I've looked through the specification. It's OK for me, but I do not get > > whether the attached extensions are crypto-protected. > > No, as these values are inserted by the administrator of the system, > or us (the distributor of the software), we didn't feel we needed the > introduction of additional PKI. > Well, the specification I suggest should allow applying CLPs issued by major vendors (Mozilla etc). For this purposes the CLPs should be validable => signed. > How do you see the infrastructure on the > draft-belyavskiy-certificate-limitation-policy? Who do you envision > signing these structures? (I assume that distribution of data will be > done by software distributors?) > I anticipate some ways to distribute CLPs. 1. Major vendor-issued CLPs are distributed either by vendors or by OS vendors (similar to, e.g., ca-certificates package in Debian). In this case we should have certificates to sign these CLPs distributed together with these bundles. 2. App-specific CLPs may include the key as a part of the application bundle. So CLP is distributed via normal app-distributing channel. 3. Locally created CLPs. This is the case more or less similar to the p11-glue solution, if I understand it correctly. Various protocols, such as TAMP (RFC 5934) can be used for transport the CLPs too. > > >> 4. How do you handle extensions to this format? > >> > > Simillary to CRL. Do you have ideas of the extensions? > > One problem with that is the fact that the existing CRL extensions are > about extending attributes of the CRL, rather than adding/removing > attributes to the certificate in question. > For this purposes I implied that the limitations are provided not by extensions, but as SEQUENCE of limitations related to the certificates. Was I wrong in the ASN1 scheme in the current version of my draft? > To bring the stapled extensions to your proposal, you'd need the > Extensions and Extension fields from RFC5280, and > add into limitedCertificates structure (I'll split it on the example > below for clarity) the following field. > > LimitedCertificates ::= SEQUENCE OF LimitedCertificate > > LimitedCertificate ::= SEQUENCE { > userCertificate CertificateSerialNumber, > certificateIssuer Name, > limitationDate Time, > limitationPropagation Enum, > fingerprint SEQUENCE { > fingerprintAlgorithm AlgorithmIdentifier, > fingerprintValue OCTET STRING > } OPTIONAL, > limitations SEQUENCE, > } OPTIONAL, > }; > > > stapledExtensions Extensions; <----- NEW > } > Sorry, I do not get the difference between the purposes of the field 'limitations' and 'stapledExtensions'. > Another difference between this profile and the p11-kit one, is that > the extensions/revocation here is done on the certificate, while in > p11-kit is done on the public key. Both approaches have pros and cons. > Sure. > > Another question. I also noticed the fingerprint field above. Is that > to distinguish between same CAs with different keys? In that case > using the SubjectPublicKeyIdentifier may be sufficient, and more > natural as this is how certificates with matching DNs/serials are > distinguished. > Do you mean Subject Key Identifier (RFC 5280, 4.2.1.2)? Yes, I agree and I'll update the draft. I introduced the fingerprint field to distinguish bogus certs from the valid ones, but I think the SKI will be OK for this purpose. Thank you! -- SY, Dmitry Belyavsky _______________________________________________ dev-security-policy mailing list dev-security-policy@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-security-policy
