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Security vs usability: the choice with passwords

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Why do we keep ignoring advice about strong passwords?

We all need some kind of authentication process if we are to access information systems at work or at home. We know why we need to do it: to make sure we have access to our data and unauthorised people don’t.

So why do we routinely ignore such advice, particularly given the constant advice from cyber security professionals about the need for strong passwords that are changed frequently? It seems there is a significant disparity about what we do and what we want: is it security or is it usability?

Most authentication we encounter today is typically implemented in one (or more) of three ways:

·         Something you know (such as the humble password)

·         Something you have (a smart card)

·         Something you are (a fingerprint).

Many systems use a username/password pair for access control, largely because the interfaces to most systems have typically been some sort of keyboard. Some smart phones use a PIN or fingerprint and bank ATMs use a combination of something you have (a card) and something you know (a PIN).

The trouble with passwords

Having a long random password is good advice. It provides a measure of security for guarding access to important information, such as your online banking account.

Unfortunately, when faced with having to remember several random 15 character passwords (characters being A to Z, a to z, 0 to 9 and an assortment of other printable characters such as ! @ # $ and %), most users apply a judgement to the value of the information protected by the password and act accordingly.

Some accounts may have a relatively weak password, because of the cost of undue information leakage or harm to the owner if the account is compromised. Other accounts might have a stronger password, because users don’t want their money siphoned off by a cyber-criminal. These are judgements about the perceived value of the information.

How safe is your password?

If you must use a password, what makes a good one? How fast can a password be cracked?

There are several websites that publish lists of common passwords. I have used a list of 14 million passwords as a test with a local science discovery centre in Perth.

Attendees at the centre (mostly high school students) were asked to enter what they thought was a secure password and this was checked against the list. If not found on the list (a rare occurence), the password was sent to a fast computer for further processing.

This computer could crack a random six character password in under two seconds, using a brute-force attack by trying to match “aaaaaa”, then “aaaaab”, then “aaaaac” and so on through all combination of six characters.

It was surprising how little the fast computer had to do. Many users assume that words or phrases taken from well-established literature are somehow secure. They are not (forget anything from Lord of the Rings or War and Peace).

A longer password takes longer to crack. A random 15-character password might take a week, but then the argument comes back to the time value of information. If a cyber-criminal has to wait a week, your account will still be there and will you change your random 15-character password every week?

One way to add an extra level of security to your password is to enable any two-step authentication, whereby another code is sent to a device, such as your mobile phone, after a password is entered. Plenty of online services already offer this service.

 

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