Author: Jasen Betts Date: To: exim-users Subject: Re: [exim] Storing messages in Maildir format with symmetric
encryption
On 2022-12-11, Dengler, Gabriel via Exim-users <exim-users@???> wrote: > Hey Heiko,
>
> in the meantime, I made great progress with the "transport_filter" tool.
> That was exactly what I was looking for.
>
> In the current setup, I want to store a public and a private key for
> each user, whereas the private key is encrypted by a password that is
> only known by the user. For incoming messages, I use the public key to
> encrypt them, for accessing those messages you need the private key,
> respectively.
>
> As mentioned in the documentation [1], you can use expansion variables
> to pass to the "transport_filter". Is there an easy way to access the
> user name or do you have to filter it out of the headers, e.g. by
> accessing "Envelope-to:"? I thought about $recipients [2], but this is
> not available for "transport_filter".
You can save $recipients into an $acl_m_ variable in the data
acl and thus have the value available when doing delivery, but how
will that help? - recipients may be multiple...
When encrypting you need a single. if it's handling a single recipinet
you get you get $domain ansd $local_part which are probably what you
want. They're tainted so use them in a lookup to find the public key
(or the filename). some transports can handle muiltipe recipients in
a single transaction. they'll need to be configured to not attempt
that.
