Double Blind Passwords (aka Horcruxing)

It really isn't good advice though. Having offline generators and rings is a good idea. I suggested using 2FA and a Yubikey for exactly the same reason. Simply adding a bit of complexity to the "what you know" factor doesn't add much security because the means of compromise of one mean the other is also likely compromised, as well as some other problems I mentioned in my own main post.

AJ Henderson As you correctly point out, just having a scheme to create randomness, plus a mentally-remembered 'horcrux' isn't 2FA. It serves only to keep full passwords from residing in one place.

My widgets were specifically created for people who are techno-phobic, who in my experience were resistant to using any sort of software wallet solution -- at least it gets them to stop using the same password or a trivial variant thereof, across all their accounts...

As always, defense-in-depth is important; each measure can serve to incrementally improve security.

R. M. yeah, to be clear, I think your devices are a good idea. My point was mostly that this original post isn't really that useful of an idea. Much better to harden the password storage instead, which is exactly what an offline device does for you.

For that system, you have to have a system you trust to make a cryptographically secure one time pad. If that software or hardware is compromised your entire system falls down still.

AJ Henderson

Obviously that's true of any system you write your message on....

Joseph No, if the computer you write the message on isn't attached to the internet, you don't really care that much if it's a bad actor as long as it isn't expected that it has updates that might specifically target your scheme, but if you are going to question the security of the hardware in general, you should also be questioning the security of whatever you are using to generate your pad.

If you do accept things at the algorithmic level but not the client/protocol level, then you can get pretty close to the same by just nesting encryptions of a root key and use something like AES as well.

Mostly I was just pointing out that if you don't trust the cryptographic principles of your own clients, you still have a single point of failure on the cryptographic principles of the offline "magic wand", if you do trust the cryptographic principles of the machine, then you don't need the in-between steps necessarily.

AJ Henderson

I already mention that the Magic Wand is an offline not internet connected device.

This supports the security attack profile even if the NSA for example has cheated and fixed your cryptosystem.

Joseph But it doesn't fix it. Even if offline, if the NSA has put a pattern in to the CNG of Windows for example and you use the randomness from that machine, they may be able to defeat it and thus defeat your one time pad.

Granted, you might be able to get around this by having multiple systems work together to form the one time pad, all offline.

AJ Henderson

Please read the website. I already say the hardware should have a good random (ideally hw source) source of randomness.

Except that salting is only intended to make the use of rainbow tables inefficient. It doesn't add a security benefit beyond making it harder to attack an individual password. In this case, it's more accurate to say that in the compromised password DB scenario, this provides a very weak password as a protection against the main password being converted to effectively being a salt.

Unfortunately, that's not likely to do much if someone has both a compromised hash table and your main password and the simple "horcrux" would rapidly be found by brute force hashing given it is short and rememberable.

Cool! I have an add on to your add on, instead of pressing the left key 4-5 times before entering the ‘horcrux’ - how about replacing part of the stored password? Eg, the first or last 4 characters?

Thanks Szymon :)