The crypto conversations are interesting, but at the end of the day, a lot of security is unavoidably contributed by the master password strength. I’d like to offer up a simple contribution. Agilebits should make two non-cryptographic changes in addition to any crypto changes.
These relate to the human end of the issue, and how real humans make decisions. That is, picking a master password is a one time event, and even if there’s a strength meter, factors of memorability, typability, etc all come into play when the user selects a password when first installing 1Password.
Those human factors are not good for security, but I think they’re addressable.
First, the master password entry screens should display the same password strength meter that’s displayed everywhere else. It’s all well and good to discuss in a blog post that people need strong master passwords, but the software should give regular feedback about the strength of that master password. Displaying a strength meter each time it’s entered creates some small risk of information disclosure via shoulder-surfing, and adds pressure to make it stronger.
Second, they should make it easier to change the master password. I looked around, couldn’t figure out how to do so in a few minutes. [Update: It’s in preferences, security. I thought I’d looked there, may have missed it.]
If master passwords are so important, then it’s important for the software to help its customers get them right.
There’s an interesting link here to “Why Johnny Can’t Encrypt.” In that 1999 paper, Whitten and Tygar made the point that all the great crypto in PGP couldn’t protect its users if they didn’t make the right decisions, and making those decisions is hard.
In this case, the security of password vaults depends not only on the crypto, but also on the user interface. Figuring out the mental models that people have around password storage tools, and how the interface choices those tools make develop those mental models is an important area, and deserves lots of careful attention.