How to get pam_ecryptfs.so to NOT use the login password?

Asked by Jakob Unterwurzacher on 2010-08-22

I want to use a strong password for the encryption. But as I have to type the login password quite often (sudo, screensaver), I want to make that one easy to type. At the moment I use EncFS with pam_encfs.so that asks explicitly for the encryption password.

How to get pam_ecryptfs.so to do that?

An idea was to insert a module "pam_askpass.so" in the pam stack that just asks for a password and stores it in PAM_AUTHTOK. Problem is, something like "pam_askpass.so" does not seem to exists. Or does it?

Question information

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eCryptfs Edit question
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Last query:
2010-09-24
Last reply:
2010-09-24
Launchpad Janitor (janitor) said : #1

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Launchpad Janitor (janitor) said : #3

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Serge Hallyn (serge-hallyn) said : #5

I haven't gotten to it myself yet, but I would recommend trying pam_mount.so
in place of pam_ecryptfs.so in your case. I will be doing this myself when
I get a chance, bc I only encrypt subdirectories of my home folder, and with
separate passphrases. I'm hoping to get to testing this next week.

If you try it before then, please do post your results and anything you've
learned.

Patching pam_ecryptfs to support this turned out to be quite easy, patch is on pastebin, description is copied for convenience below. I tested it and everything works, can send you a binary for Lucid if you want.

-------------- See http://pastebin.com/6yPsdwSX -------------------------
pam_ecryptfs: Respect ~/.ecryptfs/wrapping-independent

Quoting man ecryptfs-mount-private:
> ~/.ecryptfs/wrapping-independent - this file exists if the
> wrapping passphrase is independent from login passphrase

This patch makes pam_ecryptfs check if this file exists and ask the
user for the wrapping passphrase if it does.

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