Strong enough?

There are bits of advice that anybody who has ever used seen a computer will have heard 1,000 times. Titbits so clichéd in their overuse that even a mono-syllabic footballing neanderthal should be too ashamed to use.

1. Back up your work every 5 minutes.
Ha! Occasionally I will remember this little golden nugget and think "I'll save this as soon as I finish this section". Of course I am usually 5 minutes of stubbing pointer and middle at the keyboard from the end of the section - and 4 minutes from a power cut. Some people live and learn - I prefer the thrill of living on the edge, never knowing what will happen next.

2. Make sure you use a strong password
Generally this can be paraphrased as "Don't use the name of your pets, children, spouse, favourite football team or any word from the dictionary".

The trick is to use some system that will make your password easy for you to remember but difficult for other people to guess. Generally this involves picking a word or phrase and using a mix of upper and lower case characters and/or replacing some letters with numbers (i.e. 3 for E, 1 for I or 0 for O).

Today I had the pleasure of remotely logging into a client network. The password they had assigned my account was a completely random collection of 20 numbers, letters and special characters. It was certainly a strong password as, short of suddenly developing autism, I had no chance of ever remembering it. So.... I wrote it down.

Doesn't that kind of defeat the purpose?

Is it possible to create a password so strong that is ultimately weak?