Generating Random Passwords

PowerShell Script

The following function generates a random complex password string.

By default it will return a 16 character pattern featuring:

• At least 1 lower case letter
• At least 1 upper case letter
• At least one number; and
• 6 non-alpha characters.

It’s length and number of non-alphanumeric characters are parameterised and may be supplied if desired.

function New-ComplexPassword {
    [CmdletBinding()]
    [OutputType([String])]
    param
    (
        [Parameter(
            Mandatory = $false,
            ValueFromPipelineByPropertyName = $true,
            Position = 0)]
        [ValidateNotNull()]
        [Int]
        $PasswordLength = 16,

        # A validation is done here otherwise it may never meet the criteria for upper, lower, number etc
        [Parameter(
            Mandatory = $false,
            ValueFromPipelineByPropertyName = $true,
            Position = 1)]
        [ValidateScript( { $_ -lt $PasswordLength - 2 })]
        [Int]
        $NumNonAlphaChars = 6
    )
    process {
        # Using the .NET supplied method with customisations.
        Add-Type -AssemblyName 'System.Web'
        $validPassword = $false
        do {
            $generatedPassword = [System.Web.Security.Membership]::GeneratePassword($PasswordLength, $NumNonAlphaChars)
            If ($generatedPassword -cmatch "(?=.*\d)(?=.*[a-z])(?=.*[A-Z])") {
                $validPassword = $True
            }
        } While ($validPassword -eq $false)
        $generatedPassword
    }
}

PowerShell Sample Output

New-ComplexPassword

U]+1M?05+bf]Q)ZD

New-ComplexPassword -PasswordLength 8 -NumNonAlphaChars 2

Z75{If>7