Unique Memorable PasswordsPublished: Sun, 15 Jul 2012 14:15:28 GMT
I’m sure you’ve seen reports in the news recently of all the online services which have been hacked causing their users' passwords to be exposed.
Assuming the website has followed best practice and only stored salted password hashes, this shouldn’t be a big deal as it will take the hackers some time to decode the password and in that time you can log on and change your password. However, a lot of people will use the same password on multiple services. This means that, if a hacker gets access to one password, he may be able to log into lots of other services using your account.
The Security industry is constantly reminding people not to use the same password for multiple services, but this is an almost impossible task.
I recently spent a couple of days tracking down all my online accounts and setting secure passwords on all of them – I found 78 different accounts – there is no way I could remember 78 unique passwords without some sort of reminder.
A few years ago I came up with one solution, but I think I now have the beginnings of a better one.
My original solution was to come up with a password which I would be able to remember – I used a line from a book, taking the first letter of each word to make up the password.
For example, if I chose the line “It was a bright cold day in April, and the clocks were striking thirteen.”, my password would be IwabcdiA,atcws13. That’s not a bad starting point as it’s easily memorable, 17 characters long, it has upper and lower case letters, numbers and symbols. But, we now need some way to make it unique to each site.
I added the consonants from the site name to the middle of the password. For example, www.google.com would become “Ggl” and my password would be IwabcdiA,Gglatcws13.
My twitter password would be IwabcdiA,Twttratcws13.
The problem with this system is that an attacker who finds one of your passwords might recognise the string “Twttr” as being related to Twitter and be able to guess your other passwords.
I realised that it would be more secure to have completely unique passwords for every site, and tried to find a way of performing some sort of hashing algorithm on the domain name with and appended salt mentally to produce a unique password. It turns out this is pretty difficult to do.
I came up with the following system which will allow you to work out your password with a pen and paper – I think this is better than having your passwords written down, and does not rely on having access to a password manager (although I have a solution to that too!)
Ok, bare with me – this gets a bit complicated, but after you have done it a couple of times it becomes easier. I’m not a cryptographer, so I can’t vouch for this being at all secure, use it at your own risk.
In my opinion, though, it must be more secure than using the same password in multiple places.
- Firstly, choose a secret number, say 5 numbers long. I’ll use 35187 as an example – this is used for every password
- Next, take the domain name – example.com
- Use RotX on each of the numbers where X is a digit of your secret number. RotX just means to count X letters through the alphabet from your starting letter. So, C Rot5 would become H (count in your head “C,d,e,f,g,H”) We will change our domain name e+3, x+5, a+1, m+8, p+7 (then repeat your number as necessary) l+3, e+5, .+1 (I’ll come back to the dot in a second), c+ 8, o+7, m+3
- We now have hcbuwoj.kvp
- Where there is punctuation, count the number of characters before the symbol and use [shift]+number to create a symbol. In this case, hcbuwoj has 7 characters, and [shift]+7 gives an & symbol.
- We now have hcbuwoj&kvp
- Transpose (swap) each pair of characters – this becomes chubow&jvkp
- Capitalise all characters which are on the left side of the keyboard – this becomes ChuBoW&jkp
- Before each group of capital letters, enter the number of preceding lower case letters – we now have 0Chu2Bo1W&jkp
- Before each number insert [shift]+[n+1], that is, increase the number by one and insert the symbol which you get by typing shift and the number. On a UK keyboard, this gives !0Chu£2Bo”1W&jkp which is your final password.
You can, of course, come up with your own set of steps and customise to suit your own taste. The idea is to come up with a password which looks as random as possible and does not obviously relate to the original domain name. This system may be useful where you are travelling across borders and do not want to transport passwords which could be intercepted by the authorities.
You can make some changes to the above steps to speed up the generation process – for example step 8 can be done at the same time as step 3.
Do you have any better systems, or see any holes in the system? Let me know in the comments!