Use same key for S/MIME and OpenPGP

Werner Koch wk at
Thu Feb 22 09:24:53 CET 2007

On Mon, 19 Feb 2007 23:45, mail at said:

> I'm just curious: since a RSA public key is made mainly of just two
> numbers, is it not possible (theoretically) to create both a valid
> PGP key and X509 certificate using the same key information, and use
> it with both protocols?

Yes, you can do that.  In fact we are doing this already with the
OpenPGP smart card and Scute.

> Also, is it not (theoretically) possible to convert X509 key
> certificates to PGP key signatures or vice-versa, based on the
> numerical values of the signing certificates/keys ?

It does not buy you anything unless you have not enough space to store
both keys (the case of a smart card).



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