Comments on: Introducing Strongbox

By: Spike

Spike — Fri, 24 Apr 2009 15:28:54 +0000

If I’m following you correctly, the data encrypted with “master-pem” needs to be accessible to all users. I think adding the extra layer of per-user keys makes thing more manageable, especially if you need to revoke someone’s access. I see the weakness being pretty much the same either way; if an account’s decryption password is compromised then the data is vulnerable.

Strongbox protects against an attacker grabbing your data. What it can’t protect against is an attacker who infiltrate the system deeply enough to monitor and collect the private key password(s).

By: Frank Woeckener

Frank Woeckener — Wed, 22 Apr 2009 15:52:26 +0000

I have – say – a User-model and want to provide a separate pem-file on a per instance basis. So I changed the lock.rb-file lines #16 and #17 of your gem (thank you a lot for that!) to:

@public_key = options[:public_key] || File.join(RAILS_ROOT,’config’,”#{@instance.class.name.downcase}_#{@instance.id.to_s}.pem”)

@private_key = options[:private_key] || File.join(RAILS_ROOT,’config’,”#{@instance.class.name.downcase}_#{@instance.id.to_s}.pem”)

Now it looks for user_1.pem, user_2.pem etc. under config/ for each user – this works so far.

I planned to use the user.secret entrys to encrypt a ‘master-password’, the phrase to a ‘master-pem’ with which I would encrypt all the real stuff, so that I could have a) one(1) master password that is used for the real data and b) separate user passwords that are just necessary to decrypt the master password.

However, I feel a little uncomfortable with it, because I can imagine, that the overall encryption becomes weaker if someone knows, that all the user.secret entries decrypt to the same master password.

What do you think?
– Frank

By: Spike

Spike — Mon, 20 Apr 2009 15:41:48 +0000

The private key is protected by a password, so keeping it off the server just adds an extra layer of security. Even if an attacker gets the key, they still need to capture the password somehow.

The downside in your situation is that the user needs the private key password to decrypt the data, which could be problematic if you have many users. One approach to this, not yet supported by Strongbox, is to have one key-pair per user. You’d still have the risk of the private key password being captured, but it would limit the damage to a single user if it was.

By: Jonathan

Jonathan — Mon, 20 Apr 2009 02:48:29 +0000

I implemented something similar to this (i think) on my site.

You mentioned that if you only decrypt the data occasionally, then you may not want to have the private key deployed on the server. That makes sense, and it seems to me that your data would be safe if the server is hacked. But what if some of the encrypted data needs to be decrypted every time the user logs in? If somebody hacks the server and they have access to everything, then they can essentially look through the code, see where the private key is, and decrypt everything. Right?

Is there any way to do decryption on every login and not have the data susceptible to theft if the server is compromised?