I do use full disk encryption, but when I'm logged in, any program that runs as me can access my files (subject to some partial restrictions that Apple introduced a while ago). And anyone gaining access to my unlocked computer can easily copy that password file.

You could say once malware is executed with my credentials it's game over anyway. But I disagree with that. Having a file full of passwords stolen is far worse than than anything else, including key loggers, because it's maximum damage in a minimum amount of time.

I want to make that as difficult as possible for any attacker.

> when I'm logged in, any program that runs as me can access my files

On Windows, the same is true of the encrypted data; any program that runs as you can decrypt it. Is it different on macOS? How does the system authenticate a specific program?

On the Mac, Safari and Chrome store passwords in a key chain. To reveal any of those passwords you have to re-enter your macOS login password or whatever authentication method was used to log into the device (fingerprint, face ID, ...).

So it's not the program that is authenticated. The system simply makes sure that any program accessing that particularly sensitive data is really controlled by the logged in user.

This is entirely separate from protections for other files that may or may not be encrypted.

>Chrome store passwords in a key chain

Really? I thought Chrome, same as Firefox, stored credentials in an SQL file, the reason behind it being profiles and its built-in sync service.

It appears you're right. Chrome doesn't actually use the system key chain underneath, but the UX is exactly the same as Safari.

Autofill doesn't require password entry, but before revealing any stored passwords you have to re-authenticate using the regular system login method.

I wish Firefox did the same.

That's interesting and I wonder how they do it. Nevertheless this isn't good as it offers a false security sense since the end result is similar to using a master password which is the same as the login password.

You are more likely to lose your data while the computer is on and drives decrypted than when it is off. The threat model for FDE is thieves or government physically stealing your drive. Much more people get pwned in software than physically. I mean you don't just leave root shells laying around do you?

The question was whether the keychain really protects from those software attacks. I wondered mostly because I know that Windows will allow any process running as a certain user to decrypt data stored by any other process (at least if it's stored using the Data Protection API, like Chrome does for its passwords), so it only really protects your data from other users and their malware.

It seems that macOS authenticates each process, so that might provide some extra security.