We all carry debit cards, credit cards and mobile phones, and most of these items require a four digit pin to unlock them. Shockingly, it appears that one in every 10 people uses the same pin – 1234.
Theoretically, there are 10,000 possible four-digit combinations the numbers 0 to 9 can be arranged into, and if everyone selected a number entirely at random that would offer a reasonable level of protection.
People, however, seem to exhibit a staggering lack of imagination and select very predictable numbers. This is probably because people choose numbers that are easy to remember, but this unoriginality leaves them vulnerable.
Recently, I performed detailed analysis on 3.4m four-digit pins that had been exposed online: you can see the full details of the research here. The table below shows the top 20 pin numbers in use.
1234 accounts for 10.7% of all pins, followed by 1111 and 0000. Just these three combinations account for 18.6% of pins and the most common 20 combinations are responsible for more than a quarter of all pins in use. Statistically, to get a third of all pins you'd need to try just 61 combinations, and to guess half would require only 426 distinct combinations.
The most common numbers are repeating patterns, couplets and straights, but also high on the frequency charts are years (all the 19xx numbers occur in the top 20% of all pin numbers), as well as significant dates (1984 and 2001, for example) and popular culture references: in homage to James Bond, 0070 and 0007 also appear very high in the charts.
Also significant are keyboard patterns, such as 2580, which is a "straight-shot" down the middle of a keypad, and "across the corners" combinations are similarly popular.
What appear to be birthdays or anniversaries are present in the dataset in both the European format (DDMM) and American format (MMDD), and this is a another security pit as these are easy for a potential thief to obtain.
In America, a driver's licence, which everyone carries in their wallet with their ATM card, contains birthday information providing a thief with both the lock and key in the same location. If you have difficulty remembering a pin and elect to use a birth date, at least use that of your spouse.
At the other end of the scale, the least frequently used number I found in my dataset was 8068. Out of all the combinations of numbers this appeared to be the least interesting. It's not a date in history, it's not a pattern, it's not a birthday, it's not easy to type. It's the perfect pin … or it would have been until now. If your pin appears in the top 20 I suggest you go and find your own uninteresting number.
