Sincerely,
Giang Nguyen
----------------------------------------
> Date: Fri, 13 Mar 2009 00:22:56 +0100
> From: st...@openssl.org
> To: openssl-users@openssl.org
> Subject: Re: Can't recognize intermediate CA
>
> On Thu, Mar 12, 2009, Rene Hollan wrote:
>
>> Yeah, I just noticed that.
>>
>> I've been comparing how my intermediate CA resigned an existing cert
>> (it's part of a proxy that decrypts, examines, and reencrypts -- the
>> downstream client sharing a trust hierarchy with the intermediate
>> "resigning" CA) with what "OpenSSL ca ..." does.
>>
>> OpenSSL ca ... actually puts the issuer of the issuer into the AKID
>> issuer field of the signed cert, along with the issuer serial number.
>> When the issuer is a root ca, it is it's own issuer, so the issuer
>> (which is what my resigning code was using), and issuer's issuer are the
>> same. But, when the issuer is an intermediate CA, they are different.
>>
>> So, either I'm doing it wrong, or OpenSSL ca ... Is doing it wrong (but
>> consistent with how OpenSSL verify ... checks).
>>
>> At this point, I think the error is mine. At least browsers accept the
>> cert when OpenSSL signs it with an intermediate CA, and not when I do.
>>
>> Think about it: the purpose of the AKID is to identify the public key of
>> the signer, either by matching the SKID of the signer, or some other
>> means of identifying the signer. Well, the signer's serial number is
>> unique within those issued by IT'S signer, so the combination of IT's
>> signer and IT's serial number should be probabilistically unique.
>>
>> This whole SKID/AKID mess comes about because issuer and subject DNs are
>> not guaranteed to be globally unique, but the combination of issuer's
>> issuer DN, and issuer's serial number within the issuer's issuer's DN
>> are statistically more so. (Without SKID/AKID, one would have to verify
>> a prospective issuer by unhashing the signature with the issuer's public
>> key, which is arguably more computationally expensive that comparing
>> SKID and AKID. One should still do this anyway, but the SKID/AKID check
>> preemptively eliminates the wrong issuer).
>>
>> Sigh. X500 looks like a royal "designed by non-technical committee"
>> mess.
>>
>> Thanks for the help, now excuse me while I make a code change.
>>
>
> If it's any consolation you aren't alone with that, it gets commented on quite
> often so much so in fact that it has an FAQ entry:
>
> http://www.openssl.org/support/faq.html#USER15
doh, that makes sense! thanks.
_________________________________________________________________
Hotmail® is up to 70% faster. Now good news travels really fast.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_HM_70faster_032009______________________________________________________________________
OpenSSL Project http://www.openssl.org
User Support Mailing List openssl-users@openssl.org
Automated List Manager majord...@openssl.org
