Adam Back <aba@dcs.ex.ac.uk> writes:

Peter Gutmann writes:

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open-pgp public keys aren't based on X.509 keys, so I would've thought s/mime implementation would barf on them.

Actually S/MIME *could* support the use of PGP keys, but there's a field (the SubjectKeyIdentifier) missing from the CMS SignerInfo which prevents this.

Surely this in itself should be a compelling argument for inclusion of the SubjectKeyIdentifier?

I'm trying to get this adopted for CMS, the underlying data format for S/MIME. The silly thing about this is that alternative key identifiers (like PGP keys) were going to be included in RSADSI's PKCS7v2, but aren't included in the IETF version of the same thing. The result is that you have a private company going out of its way to accomodate open standards, and the IETF going out of its way to lock them out. Weird.

If it allows conversion of PGP keys into S/MIME X.509 keys.

You don't need this conversion, with key identifiers you can use both SPKI and PGP keys directly within S/MIME. There's no need to convert them into an X.509-like format first. Peter.