109
Signal under fire for storing encryption keys in plaintext
(stackdiary.com)
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 06 Jul 2024
109 points (100.0% liked)
Free and Open Source Software
17949 readers
218 users here now
If it's free and open source and it's also software, it can be discussed here. Subcommunity of Technology.
This community's icon was made by Aaron Schneider, under the CC-BY-NC-SA 4.0 license.
founded 2 years ago
MODERATORS
There are system specific encryption methods like keychain services on iOS to store exactly this kind of sensitive information.
How would that provide additional security in the particular circumstance of someone having access to the Signal encryption keys on someone's phone?
This particular scenario involves the MacOS desktop app, not the phone app. The link is showing just an image for me - I think it’s supposed to be to https://stackdiary.com/signal-under-fire-for-storing-encryption-keys-in-plaintext/
That said, let’s compare how it works on the phone to how it could work on MacOS and how it actually works on MacOS. In each scenario, we’ll suppose you installed an app that has hidden malware - we’ll call it X (just as a placeholder name) - and compare how much data that app has access to. Access to session data allows the app to spoof your client and send+receive messages
On the phone, your data is sandboxed. X cannot access your Signal messages or session data. ✅ Signal may also encrypt the data and store an encryption key in the database, but this wouldn’t improve security except in very specific circumstances (basically it would mean that if exploits were being used to access your data, you’d need more exploits if the key were in the keychain). Downside: On iOS at least, you also don’t have access to this data.
On MacOS, it could be implemented using sandboxed data. Then, X would not be able to access your Signal messages or spoof your session unless you explicitly allowed it to (it could request access to it and you would be shown a modal). ✅ Downside: the UX to upload attachments is worse.
It could also be implemented by storing the encryption key in the keychain instead of in plaintext on disk. Then, X would not be able to access your Signal messages and session data. It might be able to request access - I’m not sure. As a user, you can access the keychain but you have to re-authenticate. ✅ Downside: None.
It’s actually implemented by storing the encryption key in plaintext, collocated with the encrypted database file. X can access your messages and session data. ❌
Is it foolproof? No, of course not. But it’s an easy step that would probably take an hour of dev time to refactor. They’re even already storing a key, just not one that’s used for this. And this has been a known issue that they’ve refused to fix for several years. Because of their hostile behavior towards forks, the FOSS community also cannot distribute a hardened version that fixes this issue.