In an earlier post I talked about password hygiene, and about the challenges we have in keeping passwords secret.  I realised that I’d missed the opportunity to talk about why we need passwords – so I thought I’d cover it now.

Computers will – if set up “normally” – ask for a username and password after you switch it on.  This is a process called authentication (though more commonly we call it logging in or logging on), and in the early days (before the Internet existed) was seen as quite a good way of ensuring that the person entering the username is who they say they are.  One reason why this is important is so that there is some accountability on systems: if something bad has happened, it can often be tracked back to a specific username. The person who “owns” that user name can be held accountable – and those who don’t “own” it can be discounted as the culprit.  It’s therefore quite a good protection mechanism for the other users.

Once that single computer was connected to lots of others, and particularly when connected over the Internet, some people found a challenge in trying to access those remote systems by trying to guess usernames and passwords (at a very basic level this is what hackers try to do).  Passwords which are easy to guess mean that the bad guys don’t have to work very hard to access your account.  Once they have access to your computer, they will often try to see what else they can get access to, such as your bank account, financial details, holiday plans etc.

Have a look at the image below:

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It’s obvious that the most common passwords (and therefore the easiest to guess) haven’t changed much over the previous 5 years.  This is bad!

The bad guys use a range of software tools to try to break (or crack) passwords, and generally speaking the longer the password, the better.  But, length alone isn’t the answer.  If the password is just numbers, the bad guys “only” need to try combinations of 0 to 9 in increasing lengths i.e. 0,00,01,02,03 etc. If it’s just lower or upper case letters ie a to z or A to Z, then there are 26 variables which they need to try before moving on to a longer length.

Mixing numbers, upper and lower case letters and special characters (eg !@£$%^) gives a much longer set of variables which need to be tried, and this mix is what is called a complex password.  In all cases, the longer the combination of these the better, but the industry standard is a minimum of 8 characters long.  Personally, I prefer at least 15 characters, because the maths shows that with current computing power complex passwords of that length are very, very difficult to crack

Obviously, the longer and more complex the password, the more likely you are to forget it, which is why good password hygiene is required.  Password hygiene can be compared to personal hygiene, and more particularly your underwear.

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So – keep your passwords to yourself, change them regularly, and don’t show them to anyone else!

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