Re: [pkix] [Technical Errata Reported] RFC5280 (7661)

["David A. Cooper" <[e-mail]>]

While the term cross-certificate is commonly used to only to refer to 
certificates issued between "peers" where each CA issues a certificate 
to the other CA, a cross-certificate is any certificate issued by one CA 
to another CA.  There is no requirement for certificates to be issued in 
both directions. And, the definition in RFC 4949 is not correct in 
suggesting that a certificate is only a cross-certificate if the issuer 
and subject are in different PKIs (whatever that means).

As Section 3.2 of RFC 5280 notes "Cross-certificates are CA certificates 
in which the issuer and subject are different entities."

The errata is correct that "signature key used for issuing certificates" 
could be interpreted as referring to a private key. This could be fixed 
by simply deleting the clause "that contains a CA signature key used for 
issuing certificates."

On 9/28/23 8:54 AM, Russ Housley wrote:
> Cross certification results in each CA issuing a certificate to the other.  Dropping the second sentence is not helpful in my view.
>
> Russ
>
>
>> On Sep 28, 2023, at 9:10 AM, RFC Errata System <[e-mail]> wrote:
>>
>> The following errata report has been submitted for RFC5280,
>> "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile".
>>
>> --------------------------------------
>> You may review the report below and at:
>> https://www.rfc-editor.org/errata/eid7661
>>
>> --------------------------------------
>> Type: Technical
>> Reported by: Benjamin Strauss <[e-mail]>
>>
>> Section: 3.5
>>
>> Original Text
>> -------------
>>       (g)  cross-certification:  Two CAs exchange information used in
>>            establishing a cross-certificate.  A cross-certificate is a
>>            certificate issued by one CA to another CA that contains a CA
>>            signature key used for issuing certificates.
>>
>> Corrected Text
>> --------------
>>       (g)  cross-certification:  Two CAs exchange information used in
>>            establishing a cross-certificate.
>>
>> Notes
>> -----
>> The removed sentence is factually inaccurate and misleading: "A cross-certificate is a certificate issued by one CA to another CA that contains a CA signature key used for issuing certificates."
>> A "signature key used for issuing certificates" would be a private key.  A certificate simply does not contain a private key.  A definition of "cross-certificate" for the purpose of this RFC is already provided in section 3.2, so there is no point in elaborating here.
>> (The definition given in section 3.2 conflicts with the narrower, and more generally used, definition given in RFC 4949, but that is beside the point.)
>>
>> Instructions:
>> -------------
>> This erratum is currently posted as "Reported". If necessary, please
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>>
>> --------------------------------------
>> RFC5280 (draft-ietf-pkix-rfc3280bis-11)
>> --------------------------------------
>> Title               : Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile
>> Publication Date    : May 2008
>> Author(s)           : D. Cooper, S. Santesson, S. Farrell, S. Boeyen, R. Housley, W. Polk
>> Category            : PROPOSED STANDARD
>> Source              : Public-Key Infrastructure (X.509)
>> Area                : Security
>> Stream              : IETF
>> Verifying Party     : IESG