Subject: Re: X.509 ACs vs. SPKI?

From: "Aram Perez" <[email-masked]>
Date: Fri, 28 May 1999 09:12:13 -0700

Denis Pinkas wrote:

> Steve,
> 
> I agree with your response
> 
> In ESS (from the S/MIME WG) there is the following structure which
unambigously
> references an certificate.
>
> ESSCertID ::=  SEQUENCE {
>      certHash                 Hash,
>      issuerSerial             IssuerSerial OPTIONAL
> }
>
> Hash ::= OCTET STRING -- SHA1 hash of entire certificate
>
> IssuerSerial ::= SEQUENCE {
>      issuer                   GeneralNames,
>      serialNumber             CertificateSerialNumber
>
> I suggest that we generalize it, to support any kind of HASH function,
> i.e. not limiting it to SHA 1.

I disagree with allowing any HASH function. If you don't specify just one
function, then you have to search the data store for every HASH function
allowed until I find the certificate.

Look at the current problem trying to verify root certificates and/or
"built-in certificates". Some browsers display the MD5 certHash (a.k.a. the
fingerprint), and others display the SHA-1 certHash. Some CAs publish their
root certificate certHashes using MD5, others using SHA-1. So the ability to
verify the root certificates of your browser depends on which browser you
have and which CA's root certificates you are trying to verify :-(  Not good
at all in my opinion.

[snip]

Regards,
Aram Perez

---

From: Stephen Kent <[email-masked]>
Date: Fri, 28 May 1999 12:41:58 -0400

Aram,

We need to remain algotihm independent, and thus we cannot insist on just
one hash function.  Our data structures that rely on hashes also specify
which hash was employed, to prevent ambiguity.  The use of hashes as
fingerprints for self-signed certs, to facilitate out of band verification
has not been a subject of standardization so far, and that is the cause of
some of the problems you cite.  We can try to encourage vendors to do the
right thing, but if we don't standardize it, ...

Steve