Author: Dengler, Gabriel Date: To: exim-users Subject: [exim] Storing messages in Maildir format with symmetric encryption
Hello everyone,
I want to store the incoming e-mails using the Maildir file format
encrypted by using some symmetric encryption using the user's password
(e.g., AES). So in the end, Exim should write the encrypted files
directly on the disk. Furthermore, it would be convenient if the actual
password is solely persistent saved as a hash (for checking at
authentication), the real password - and therefore the en-/decryption
key - is only temporarily available during the login session.
Therefore, I wanted to modify the Exim source code directly but was
confronted with a large amount of code, e.g., the differentiation
between the different transport types or the many cases considered in
the appendfile protocol. So I have some questions, where you might help
me in the "big picture":
* How to enforce that a user has to authenticate him-/herself with a
password?
* Where is a good point of "grabbing out" the password from the user and
how to "carry" it to the point where the encryption happens?
* Where is a good point to add the encryption, e.g., by modifying the
transport_instance block or directly before the file is written?
