a new free smime service, but...

Ralph Seichter abbot at monksofcool.net
Wed Oct 23 22:56:39 CEST 2019


* Steffen Nurpmeso:

> I think it is common that S/MIME and SSL certificates are delivered
> via PKCS12, including the private key. You then seem to extract the
> individual things [...]

Nope, that is the wrong way round. The correct sequence to obtain an
S/MIME certificate is as follows:

1. User X creates a private key *locally*. This private key must never
be handed to anybody else.

2. User X creates a certificate signing request (CSR) and sends it to a
certificate authority (CA).

3. The CA uses the CSR to create a signed certificate, and sends that
certificate back to user X.

4. User X can then optionally combine private key and signed certificate
in a .p12 file to ease importing the data *locally* in his MUA (it is
usually more convenient to deal with a single file that combines both
private key and certificate).

If the process is altered in any way in which a third party gets hold of
user X's private key, security is broken, no matter if the private key
is password protected or not.

-Ralph



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