Skip to main content

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).

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

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.

PPS This will not protect the user against disclosure of an individual password. Two factor systems like Google Authenticator do help there. Always enable two factor authentication if it is available.

PPPS If you read this blog post and only take one action... go make sure your email is secured.


heavymark said…
Hard to imagine anyone technical and diligent enough to generate and write down every password using diceware and use that pad for manually writing it in and every time but not smart/willing enough to use software to store the passwords.

It sounds like a tremendous amount of work, since all a person would have to do is compromise the users email account, and then when the user is sleeping reset all the passwords of accounts they find most desireable without needing to figure out the passwords of any of those other accounts.

Or for people who do use a password manager software like 1Password, even if it stores 1000s of different unique diceware passwords, a person only needs to guess the single password used to encrypt that database to access all the passwords. And most likely that single password is a common easy one since they have to type it in everytime.

With all these password schemes always best to focus on the weakest link in my opinion.
Jon Major said…
Storing passwords in a vault is my preference, especially with so many support two factor authentication now. Even if you wanted to own the data, Secret Server (free edition) supports two factor via Email. Or LastPass, if you don't mind an online solution, supports numerous two factor methods including Google Authenticator.
hl2run said…
I have my credit card PIN (I'm in Europe, so we use PIN) written on it with a bunch of random numbers in different colors and only I know the pattern I have to go thru to get the PIN :)
Don P said…
I like as I can store my passwords in a Google Doc or even Chrome bookmarks ... but only I can "unlock" the password using a single master password (I only have to remember 1 password!).

Popular posts from this blog

Your last name contains invalid characters

My last name is "Graham-Cumming". But here's a typical form response when I enter it: Does the web site have any idea how rude it is to claim that my last name contains invalid characters? Clearly not. What they actually meant is: our web site will not accept that hyphen in your last name. But do they say that? No, of course not. They decide to shove in my face the claim that there's something wrong with my name. There's nothing wrong with my name, just as there's nothing wrong with someone whose first name is Jean-Marie, or someone whose last name is O'Reilly. What is wrong is that way this is being handled. If the system can't cope with non-letters and spaces it needs to say that. How about the following error message: Our system is unable to process last names that contain non-letters, please replace them with spaces. Don't blame me for having a last name that your system doesn't like, whose fault is that? Saying "Your

How to write a successful blog post

First, a quick clarification of 'successful'. In this instance, I mean a blog post that receives a large number of page views. For my, little blog the most successful post ever got almost 57,000 page views. Not a lot by some other standards, but I was pretty happy about it. Looking at the top 10 blog posts (by page views) on my site, I've tried to distill some wisdom about what made them successful. Your blog posting mileage may vary. 1. Avoid using the passive voice The Microsoft Word grammar checker has probably been telling you this for years, but the passive voice excludes the people involved in your blog post. And that includes you, the author, and the reader. By using personal pronouns like I, you and we, you will include the reader in your blog post. When I first started this blog I avoid using "I" because I thought I was being narcissistic. But we all like to read about other people, people help anchor a story in reality. Without people your bl

The Elevator Button Problem

User interface design is hard. It's hard because people perceive apparently simple things very differently. For example, take a look at this interface to an elevator: From flickr Now imagine the following situation. You are on the third floor of this building and you wish to go to the tenth. The elevator is on the fifth floor and there's an indicator that tells you where it is. Which button do you press? Most people probably say: "press up" since they want to go up. Not long ago I watched someone do the opposite and questioned them about their behavior. They said: "well the elevator is on the fifth floor and I am on the third, so I want it to come down to me". Much can be learnt about the design of user interfaces by considering this, apparently, simple interface. If you think about the elevator button problem you'll find that something so simple has hidden depths. How do people learn about elevator calling? What's the right amount of