Subject: [pkix] Discrepancy between Signature POP RFC 2511 and RFC 4211

From: Tom Biskupic <[email-masked]>
Date: Thu, 3 Apr 2014 16:28:30 +1100

Hello,

There appears to be a discrepancy in the text between RFC 2510 and 4211 in
regards signature POP for the case where the EE has an established identity
and POPOSigningKeyInput has been omitted.
The ASN.1 comment in Section 4.4 of RFC 2510 implies the POP signature
should be over the CertReqMessage but in Section 4.1 of RFC 4211 it says it
should be over the CertTemplate.

In RFC 2511:

POPOSigningKey ::= SEQUENCE {
       poposkInput         [0] POPOSigningKeyInput OPTIONAL,
       algorithmIdentifier     AlgorithmIdentifier,
       signature               BIT STRING }
       -- The signature (using "algorithmIdentifier") is on the
       -- DER-encoded value of poposkInput.  NOTE: If the CertReqMsg
       -- certReq CertTemplate contains the subject and publicKey values,
       -- then poposkInput MUST be omitted and the signature MUST be
       -- computed on the DER-encoded value of CertReqMsg certReq.  If

                          ***************************************
       -- the CertReqMsg certReq CertTemplate does not contain the public
       -- key and subject values, then poposkInput MUST be present and
       -- MUST be signed.  This strategy ensures that the public key is
       -- not present in both the poposkInput and CertReqMsg certReq
       -- CertTemplate fields.

But in RFC 4211 section 4.1 point 3

 3.  The certificate subject places its name in the Certificate
       Template structure along with the public key.  In this case the
       poposkInput field is omitted from the POPOSigningKey structure.
       The signature field is computed over the DER-encoded certificate
       template structure.

       ******************

Is this an intended change to the protocol or have I
misunderstood/missed something?

Thanks,

Tom Biskupic

---

From: Tom Biskupic <[email-masked]>
Date: Thu, 10 Apr 2014 11:40:59 +1000

Hello,

Sorry to nag but did anyone have any thoughts on this?

Thanks,

Tom Biskupic

On Thu, Apr 3, 2014 at 4:28 PM, Tom Biskupic <[email-masked]> wrote:

> Is this an intended change to the protocol or have I misunderstood/missed something?
>
> Thanks,
>
> Tom Biskupic
>
>

---

From: "Jim Schaad" <[email-masked]>
Date: Thu, 10 Apr 2014 09:21:19 -0700

There was no change intented.  I would note that 4211 includes the following
text in the description of the signature field

      signature contains the POP value produce.  If poposkInput is

      present, the signature is computed over the DER-encoded value of

      poposkInput.  If poposkInput is absent, the signature is computed

      over the DER-encoded value of certReq.

Which is the same as the comment in 2511.

Jim

From: pkix [mailto:[email-masked]] On Behalf Of Tom Biskupic
Sent: Wednesday, April 09, 2014 6:41 PM
To: [email-masked]
Subject: Re: [pkix] Discrepancy between Signature POP RFC 2511 and RFC 4211

Hello,

Thanks,

Tom Biskupic

Hello,

In RFC 2511:

Is this an intended change to the protocol or have I misunderstood/missed
something?

Thanks,
Tom Biskupic