Author: Jasen Betts Date: To: exim-users Subject: Re: [exim] Storing messages in Maildir format with symmetric
encryption
On 2022-11-23, Jeremy Harris via Exim-users <exim-users@???> wrote: > On 23/11/2022 00:16, Dengler, Gabriel via Exim-users wrote:
>> I want to store the incoming e-mails using the Maildir file format encrypted by using some symmetric encryption using the user's password
>
> It seems like a generally valuable concept - but I'd think that assymetric encryption
> of the data-at-rest is more appropriate than symmetric. The MDA (exim, here, receiving
> a message and delivering to file) shou be able to encrypt for the destination user
> but NOT decrypt. So it should have access to a public key and not a private key
> for the destination mailbox - and this is entirely separate from notions of
> SMTP authentication.
>
> Where to implement it in the code? Probably pretty late in the appendfile
> transport; about where it's doing actual writes to the file fd - and using
> a public key supplied via a transport option (which the config pulls
> from a database lookup using the username, or localpart, or whatever)
> and perhaps another giving the cipher scheme.
Perhaps use some sort of GPG wrapper as a transport_filter,
and do decryption client-side?
