Of Passwords and PINS (1)

25 08 2012

In the world of Information Security, few things generate more debate and argument than how to authenticate a user.
Authentication is one of the two pillars of access, the other being authorisation. One to prove who you are, the other to control what you are allowed to do. You can have authorisation without authentication (for example anyone can use Google to search for something on the web) and you can have authentication without authorisation (“you may well be David, but you aren’t getting in here my son!”).
The most common authentication mechanism around is the good old userid/password combination. The biggest problem with this is that the userid is often easy to guess (or may even be made public intentionally), so it really falls back to the password on its own and for a password to be acceptable the party who owns what is to be accessed has to trust that the person who presents the password is actually the person who is meant to know it. We’ve all seen the films where the bad guys find out the secret password for entry to the castle and then massacre everyone inside. If you rely on a password as the authentication method then you have to rely on the person who knows it keeping it secret, and that it is pretty hard to guess!
Therein lies the problem. If you only have to remember one userid/password combination then it’s not beyond the wit of man to make it complex and keep it safe in your head, however a very quick count will show that you have lots of accounts which require you to authenticate yourself before you are granted access. Actually, let’s just take a few minutes to do just that. Count up all of the different computer accounts you have; at work, at home, with your bank(s?), e-mail accounts, Facebook, Twitter, don’t forget your phone, laptop, car(?) etc. etc. Passed 20 yet? Thirty, Forty, One Hundred? OK, now think how many DIFFERENT passwords you use across those accounts, is it one for all of them or a different one for each?
This is where the real world and ‘best practice’ collide, and where I will disagree with many of my colleagues. ‘Best practice’ for account management will offer you the following rules: 1. Have a different password for each account; 2. Never write your password down; 3. Change your password frequently; 4. Make your password hard to guess but easy to remember; 5. Never share your password with anyone.
4 and 5 I’ll go along with, and there are lots of places you can go to help you with the first part of 4, however the challenge can be achieving the second part at the same time. R&h(0kl.!B may well be a very strong password, but you’ll be hard pressed to remember it. I’ll come back to how to achieve both parts of (4) in the next post. To my mind 5 is a no brainer, but (and there is always a but), I’m sure you can think of situations where you want to share because it’s easier, and that is where Corporate rules and Personal choice can collide. Your employer may make it a disciplinary offence to share the password to your company account with a colleague, but you may choose to share your personal e-mail password with your partner (only you can decide if that is a good idea!!).
So let’s have a look at 1,2 and 3.
1. Have a different password for each account. Are you serious?? It’s hard enough to remember the separate accounts without having to remember all those passwords.
2. Never write your password down. You’ve just told me to have 50 different passwords, and now you expect me to remember them all? Dream on!
3. Change your password frequently. So, not only do I have to remember 50 separate, complex passwords, without writing them down, I’ve now got to change them every month or so.
And we wonder why users get upset with us.
So what can you do? This may not work for you, but it’s my solution and it seems to have kept me safe for a few years.
First step is to separate your accounts into their relative importance (perform a risk assessment if you will). Ask yourself how much pain you will suffer if someone else can use the account that you are protecting. If it’s your online bank account, then you want it pretty secure, other things you may care less about. For the ones I really care about, as there are not many of them and it’s not a massive overhead, I apply rules 1-5 in full. I then temper the rules as the risk decreases, to the point where I have a couple of passwords that I use for all of the unimportant accounts (insurance quotes, or brochure sites which feel obliged to force you to log in for some reason). Rules 4 and 5 still apply to these though.
So lets look at Rule 1. You may also decide to have one password to cover a particular group of accounts (e.g. your e-mail accounts, or your social media accounts), this has the advantage that you only have to remember one password and when it comes to changing it you only have to think up one new value. It does of course have the disadvantage that if it is compromised then all of those accounts could be at risk, so as soon as you think someone knows your password CHANGE IT! Hence the risk assessment.
On to Rule 2. If you are going to write your passwords down, then don’t write the password next to the account name it belongs to. As I said in an earlier posting, Information Security is basically common sense, and that would be plain stupid. Think of a clever way of making the relationship obvious to you, but impossible to guess for someone else. If you don’t need to carry them with you (and let’s be honest you probably don’t), then store them in a file on your computer (and don’t name it ‘my passwords’), which you could always protect with another password!
Finally Rule 3. When it comes to changing passwords, other than your Corporate accounts, I’m pretty sure that none will ever remind you, and most will never expire. Two tips here; one – if you hear about a company you have an account with being ‘hacked’ (such as the recent stories about Sony, LinkedIn and World of Warcraft), then change your passwords immediately, and 2 – never change your password in a hurry or when your mind is on something else. You WILL have forgotten it the next time you log in!

So, that’s a first toe-dip into the world of authentication. Lots more to cover in later postings, but in the meantime, as always, keep safe online, and remember –
Just because you’re paranoid it doesn’t mean they’re not out to get you!

David

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