MVC .net password validation using regular expression

Question

I'm writing a regular expression to validate a password. The conditions are:

Password must contain at least two special characters
Password must be at least eight characters long
Password must be alpha numeric

I'm able to make sure that there are atleast 8 characters, atleast one alphabet, atleast one number and atleast one special character using the below Regular expression:

(?=.*[A-z])(?=.*[0-9])(?=.*?[!@#$%\^&*\(\)\-_+=;:'""\/\[\]{},.<>|`]).{8,32}

Only condition i'm not able to get is there must be atleast two special characters (Above Reg exp is atleast one special characters). Does anyone have any idea on this?

Thanks in advance.

if it's an alphanumeric then how come it allows special chars.? — Avinash Raj
– Avinash Raj, Commented Mar 25, 2015 at 12:00
@AvinashRaj: by alphanumberic, i mean there must be both alphabet and numbers. Only issue is how to make sure that there are atleast 2 special characters. — Zax
– Zax, Commented Mar 25, 2015 at 12:02

Avinash Raj · Accepted Answer · 2015-03-25 12:02:04Z

1

Only condition i'm not able to get is there must be atleast two special characters.

Make it twice by putting the pattern which was present inside the lookahead inside a group and then make it to repeat exactly two times.

^(?=.*[A-Za-z])(?=.*[0-9])(?=(?:.*?[!@#$%\^&*\(\)\-_+=;:'""\/\[\]{},.<>|`]){2}).{8,32}$

If you want to allow atleast 8 characters then you don't need to include 32 inside the range quantifier, just .{8,} would be enough.

answered Mar 25, 2015 at 12:02

Avinash Raj

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4 Comments

Zax Over a year ago

Thanks for the reply. Tried this, this will make sure that the two special characters are appearing continiously

Avinash Raj Over a year ago

no, it asserts that the string must contain atleast two special chars. And it won't be continuous. See i make the .*? also to repeat.

Zax Over a year ago

there must be 2 special characters, but they might or might not appear continuously one behind another in the input string

Avinash Raj Over a year ago

And also [A-z] matches also the chars other than A-Z and a-z. So that i added [A-Za-z]

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