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Two factor paper passwords

Two factor paper passwords Two factor paper passwords

I guess it makes me boring but I try to get people to use stronger passwords.

People love to use the same password over and over again, or they invent some amazing scheme like the same single word followed by their birth year, or replacing a’s with 4’s. And no matter how many password database get hacked the idea that password security matters doesn’t seem to really sink in.

When I do get someone to listen I tell them to use diceware generated passwords and them write them down in a little book and guard the book jealously (actually, I tell them to use a password manager but most people seem to balk at using software I think for fear of losing their passwords).

Two factor paper passwords

So I advise them to buy something like this and thenkeep a record of their passwords generated using diceware . Usually people seem happy to have something that creates them passwords like this:

Two factor paper passwords

But then they often ask the sensible question: "What if someone steals that book?" And so I suggest a ‘two factor’ solution. Two factor authentication is often characterized as a combination of something you know (e.g. a secret password) and something you have (for example, a smartphone with an app on it that generates a unique number valid for a few seconds).

In my two factor paper passwords scheme these are reversed: the something you have is the password (since it’s written down and not something you can remember) and the something you know is how to transform the password into what you actually type in.

For example, suppose the password written down is anger lunar greek worry brown hole . The second factor might be that the second letter of each word will be capitalized. So the user would type in aNger lUnar gReek wOrry bRown hOle .

Or maybe it’s that the first vowel in each word is omitted: the user types in nger lnar grek wrry brwn hle .

Or that the first and last letters of each word are swapped: rngea runal kreeg yorrw nrowb eolh .

Or the letters at the end and start of each word are swapped: angel runag rreew korrb wrowh nole .

Or that the password is followed by digits giving the number of consonants in each word:  anger lunar greek worry brown hole333442.

Or that the number of consonants in each word is multiplied together to create a number added at the end:  anger lunar greek worry brown hole864.

There are all manner of schemes someone can use to make possession of the book useless and it’s a good way to get a user who isn’t interested in password security engaged in the topic. The goal should be something easy to remember that’s reasonably easy to compute in your head.

Of course, this doesn’t protect against an attack where a single password has leaked and someone has access to the book because they may be able to figure out the scheme used, but this is a huge advance on the poor habits of most users.

PS If you are planning to do this… please consider using a password manager first.

Two factor paper passwords

If you enjoyed this blog post, you might enjoy my travel book for people interested in science and technology: The Geek Atlas . Signed copies of The Geek Atlas areavailable.

posted by John Graham-Cumming at11:33 Permalink

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