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> I’d say defense-in-depth is more about nesting strong cryptographic primitives, than simply adding layers. I like this insight, thank you. One rebuttal I ha

> I’d say defense-in-depth is more about nesting strong cryptographic primitives, than simply adding layers. I like this insight, thank you. One rebuttal I have: appending those characters to the password would make it a stronger password, but it wouldn’t add another, wholly different, mode to authentication. It would be the same thing, just harder (and I don’t need a longer password as it stands). What if this mode is flawed in itself? That’s when a wholly different one is desirable. In that spirit, I had also thought about just slamming http basic auth in front of everything. Even if that basic auth uses weak credentials, it adds to security in a multiplicative/exponential way (multiple passwords/systems), over just a linear one (single but long password). I suppose that’s also what you mean by layering.

ratorx 4y ago
Linear/multiplicative stuff is actually quite helpful for discussing the path thing. Adding a “password” path is actually only increasing your security by a constant factor per character because of the risk of timing attacks (unless you are sure that the path matching algorithm is secure against it now and in the future). Ideally a 2nd layer would guard against it in a multiplicative way (an entirely different with system). Cryptographically, adding characters to the password rather than to the path is better (because it increases the search space exponentially) than adding characters to the path, which can be brute forced separately per character. But this assumes a very perfect view of software, where there are no bugs. Once you add a risk model for bugs, then there might be small values of path length where the additional constant factor is better than the multiplicative one that you get from adding characters to your password. So your rebuttal holds, depending on the exact bug risk model you have. I think nowadays, tailscale/wireguard is really convenient and pretty secure as a 2nd layer. I was averse to self hosting my password manager in the past due to not being comfortable having the consistent time to secure more critical applications, but I might actually move to a world where I host more critical things myself behind a VPN.

ratorx 4y ago

Linear/multiplicative stuff is actually quite helpful for discussing the path thing. Adding a “password” path is actually only increasing your security by a constant factor per character because of the risk of timing attacks (unless you are sure that the path matching algorithm is secure against it now and in the future). Ideally a 2nd layer would guard against it in a multiplicative way (an entirely different with system). Cryptographically, adding characters to the password rather than to the path is better (because it increases the search space exponentially) than adding characters to the path, which can be brute forced separately per character. But this assumes a very perfect view of software, where there are no bugs. Once you add a risk model for bugs, then there might be small values of path length where the additional constant factor is better than the multiplicative one that you get from adding characters to your password. So your rebuttal holds, depending on the exact bug risk model you have. I think nowadays, tailscale/wireguard is really convenient and pretty secure as a 2nd layer. I was averse to self hosting my password manager in the past due to not being comfortable having the consistent time to secure more critical applications, but I might actually move to a world where I host more critical things myself behind a VPN.