PowerShell - Password Generator - How to always include number in string?

Question

I have the following PowerShell script that creates a random string of 15 digits, for use as an Active Directory password.

The trouble is, this works great most of t

Answer 1

I wrote a secure password generator function in PowerShell, maybe this will be useful to someone.

Similar to the accepted answer, this script also uses Get-Random (twice), and also regular expression matching to ensure the output is secure. The difference in this script is that the password length can also be randomised.

(To hard set a password length, just set the MinimumPasswordLength and MaximumPasswordLength values to the the same length.)

It also allows an easy to edit character set, and also has a regex to ensure a decent password has been generated with all of the following characteristics:

(?=.*\d) must contain at least one numerical character

(?=.*[a-z]) must contain at least one lowercase character

(?=.*[A-Z]) must contain at least one uppercase character

(?=.*\W) must contain at least one non-word character

The answer to your question about always including a number in your generated output can be solved by checking the output with a regex match (just use the parts of the regex that you need, based on the explanations above), the example here checks for uppercase, lowercase, and numerical:

$Regex = "(?=.*\d)(?=.*[a-z])(?=.*[A-Z])"

do {
        $Password = ([string]($AllowedPasswordCharacters |
        Get-Random -Count $PasswordLength) -replace ' ')
    }    until ($Password -cmatch $Regex)

$Password

Here is the full script:

Function GeneratePassword
{
    cls
    $MinimumPasswordLength = 12
    $MaximumPasswordLength = 16
    $PasswordLength = Get-Random -InputObject ($MinimumPasswordLength..$MaximumPasswordLength)
    $AllowedPasswordCharacters = [char[]]'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!?@#£$%^&'
    $Regex = "(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*\W)"

    do {
            $Password = ([string]($AllowedPasswordCharacters |
            Get-Random -Count $PasswordLength) -replace ' ')
       }    until ($Password -cmatch $Regex)

    $Password

}

GeneratePassword