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Password management
Message
De
27/05/2013 13:20:33
 
 
À
27/05/2013 11:49:41
Information générale
Forum:
ASP.NET
Catégorie:
Autre
Versions des environnements
Environment:
VB 9.0
OS:
Windows 7
Network:
Windows 2003 Server
Database:
MS SQL Server
Application:
Web
Divers
Thread ID:
01574811
Message ID:
01574848
Vues:
33
>>>>>>>We had a discussion recently in the team about the length of what a password should be. Some would say the longest is the better. Well, while this may be good as an answer, I would be curious to know, before encryption, what is the length you usually have in your application for the member's table password.
>>>>>>
>>>>>>
>>>>>>I'd go for at least 6 chars. You can ask for eg at least one upper case char, two lower case, one digit, .. Such a test is easily done with a Regex
>>>>>
>>>>>Just vaguely wondering about the maths of password strength. Say you have a simple two character password. If you stipulate that one must upper case and one must be lower case then you are actually reducing the number of available combinations to 26x26 rather than the 52x52 which would otherwise apply :-}
>>>>
>>>>
>>>>
>>>>In that case (one upper and one lower) there are 26 * 26 * 2 possibilities ( or 52 * 26) since you can start with either upper case or lower case
>>>
>>>But still not as many as if 2 lower or two upper were also allowed.
>>
>>
>>True - but if you say at least 6, with at least one lower case and at least one upper case, then the possibilities of two (out of the 6) chars are reduced to 26. And you still have to figure out where they are
>
>True. But if I'm trying to crack a password I still have less combinations to test if I know that at least one of the characters is upper case and at least one is lower case.


I'm curious now

Say 6 chars with at least one upper and at least one lower

6 chars upper/lower is 52 ^ 6

4 chars upper/lower, one lower, one upper

is more than 26^2 * 52^4 ( since the place of the upper/lower ones are not fixed) but less than 52 ^ 6


(1) How would you go about cracking the password ?

(2) How many possibilities would you say there are ( have tried myself but ended up with more than 52 ^ 6)
Gregory
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