# Testing if a password for an eCryptfs mount is valid [closed]

I'm using "eCryptfs" on several directories on my dedicated Debian server. I mount them manually via

mount -t ecryptfs [dir] [mountpoint]


But after some weeks being mounted it's not easy to remember the exact passwords for each directory. I want to make sure that I got the right passwords before unmounting them or rebooting the server.

I thought of generating an "eCryptfs" signature and comparing it with the directory's "eCryptfs" signature. Which parameters do I need to know and what is the algorithm for the "eCryptfs" signature? And is this the right way to verify my password?

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## closed as off-topic by e-sushi, Gilles, pg1989, figlesquidge, DrLecterDec 7 '13 at 11:03

• This question does not appear to be about cryptography within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

This appears to be a tech support question about using or fixing technology to work as advertised. Unix.SE and AskUbuntu could provide more in-deep and more on-point answers on how to use the related software. – e-sushi Dec 6 '13 at 18:50

## 1 Answer

You can use the ecryptfs-add-passphrase command to add a passphrase to your kernel keyring, which will also print the signatures (hashes) to standard out.

Once you've added a passphrase to the keyring, you might want to clear it, using the keyctl command.

eCryptfs uses a PBKDF2-like, key strengthening algorithm of 65536 rounds of SHA512.

(Disclosure: I am one of the authors and maintainers of eCryptfs.)

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When you specify that it is using said algorithm, it would appear that is an algorithm used to generate a key from the passphrase, said key being used for a symetric cipher. If that is the case, how is the signature generated? – MetaChrome Dec 6 '13 at 18:02