I recently went to change my password at AliPay, and found out that there are a few restrictions on the password:
- It can only be digits
- It must be six digits
- It can not consist of consecutive digits (123456, 234567, etc.)
- It can not consist of a repeated single digit (111111, 222222, etc.)
This all seems idiotic to me. First off, six characters is not a lot. Six digits contain even less entropy. And to top it off, they remove some more possible combinations.
To be fair, I guess things like 123456 or 111111 would be at the top of any hackers "dictionary" if they were to brute force it. However, there are still only less than a billion possible combinations to try, which in this day and age is not a lot (right?).
Can there ever be any valid reason whatsoever to restrict a password like this? I use a password manager and usually default to 20 characters of random digits, letters and symbols. For a payment service in 2016 I'd expect long passwords containing random symbols to be allowed (or even demanded by the system).
So am I missing something here, or are the people who come up with these limitations just not that security minded?