PowerShell Random Password Generator

PowerShell Random Password Generator

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On a project earlier this year, I had to create random passwords for user accounts as part of a provisioning tool.  Perpetually trying to find the fastest way to do something, I came up with a one-liner that you can use to create a random text string from the following ASCII printable characters:

!”#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_abcdefghijklmnopqrstuvwxyz{|}~0123456789

To create the passwords, I use this bit of magic:

PS> $Password = ([char[]]([char]33..[char]95) + ([char[]]([char]97..[char]126)) + 0..9 | sort {Get-Random})[0..8] -join ''
PS> $Password
Z-=$fNgb!

Image result for password gif

That will create an 9 character password using the range operator [0..8]. And, if you want to concatenate it with a plaintext counterpart:

PS> $Password = ([char[]]([char]33..[char]95) + ([char[]]([char]97..[char]126)) + 0..9 | sort {Get-Random})[0..8] -join ''
PS> $Password = "Welcome"+$Password
PS> $Password
WelcomeZ-=$fNgb!

Maybe not the most difficult passwords in the world, but probably good enough to give new users the first time they log on to a system.

But then, I found this gem, too:

$Password = "Welcome" + ([System.Web.Security.Membership]::GeneratePassword(x,y))

Where:

x = length in characters
y = minimum number of non-alphanumeric characters

With “y”, you’ll specify a number from 0 to a maximum of what “x” is.

What ideas do you have?

Published by Aaron Guilmette

Helping companies conquer inferior technology since 1997. I spend my time developing and implementing technology solutions so people can spend less time with technology. Specialties: Active Directory and Exchange consulting and deployment, Virtualization, Disaster Recovery, Office 365, datacenter migration/consolidation, cheese.

Reader Comments

  2. As this post is well over a year old, you probably already know that “y” is the MINUMIM number of non-alphanumeric characters – it’s not possible to specify the exact number

  3. I recently found a method that uses the System.Web method from .NET framework. The below script will generate 10 passwords with eight characters, and will have at least 1 non-alphanumeric character. Gives me the ability to choose a suitable password for my end user:

    [Reflection.Assembly]::LoadWithPartialName(“System.Web”)

    $i = 0
    while ($i -lt 9) {
    [System.Web.Security.Membership]::GeneratePassword(8,0)
    $i++
    }

  4. I found small limitation in your script – it will use each character exactly once. This somehow bother me, and it also slightly decrease the complexity :-o, finally the length of password is always same :-o, so here is my take on it:

    $asci = [char[]]([char]33..[char]95) + ([char[]]([char]97..[char]126))
    $password = (1..$(Get-Random -Minimum 9 -Maximum 14) | % {$asci | get-random}) -join “”

  5. Thank you for this script. I ran a quick loop to check and like the results. I only wish I could exclude one character that has given me trouble in cloudformation scripts. The Ampersand (Char 37).

    Here is my quick loop script to validate this one liner.

    0..9 | % {$Password = ([char[]]([char]33..[char]95) + ([char[]]([char]97..[char]126)) + 0..9 | sort {Get-Random})[0..15] -join ”;$Password}

    Returns nine 16 character passwords.
    [{\7>h8<(R1MQj@,
    YX7ua"%j?V^PyS-b
    O%P2uA7E-hw@6oH^
    Ngs~KvE-T8G5Wu%7
    uR9=x)S2nDC,z7"H
    j)|a<7s(LO_2W31Q
    c<x5%pw4svybq,Yt
    G%Npu17W'vA*t4QS
    7V1[2ihr5cgq|=^y
    e5S?gf_41<5@o8O}

    1. You could use the Replace(x,y) method on your final password (in this example, I replace the & with the number 5):

      0..9 | % {$Password = ([char[]]([char]33..[char]95) + ([char[]]([char]97..[char]126)) + 0..9 | sort {Get-Random})[0..15] -join ”;$Password.Replace(“&”,”5″)}

      L%64uBV:\Epqk,mU
      l9V@/0cTW(‘gn,.[
      IO]G2f5;5$137″g(
      .:wIa00f”lFQimLg
      *i52^DTLm$@z,\!r
      2d\c4;LBy)D9!*U’
      _p”)i!6^dJP95/Bq
      W6602″xB\fev-Lcp
      <P|[uYF}mnbi3~6S
      0:9nQ{W@h\da5;p4

    1. What version of PowerShell are you using?

      I tested in both Windows Server 2012 and 2008 R2:

      PS C:\> $PSVersionTable

      Name Value
      —- —–
      CLRVersion 2.0.50727.5485
      BuildVersion 6.1.7601.17514
      PSVersion 2.0
      WSManStackVersion 2.0
      PSCompatibleVersions {1.0, 2.0}
      SerializationVersion 1.1.0.1
      PSRemotingProtocolVersion 2.1

      PS C:\> $Password = ([char[]]([char]33..[char]95) + ([char[]]([char]97..[char]126)) + 0..9 | sort {Get-Random})[0..8] -j
      oin ”
      PS C:\> $Password
      E8{(f)1@T
      PS C:\>
      ———-
      PS C:\> $PSVersionTable

      Name Value
      —- —–
      PSVersion 4.0
      WSManStackVersion 3.0
      SerializationVersion 1.1.0.1
      CLRVersion 4.0.30319.34209
      BuildVersion 6.3.9600.17400
      PSCompatibleVersions {1.0, 2.0, 3.0, 4.0}
      PSRemotingProtocolVersion 2.2

      PS C:\> $Password = ([char[]]([char]33..[char]95) + ([char[]]([char]97..[char]126)) + 0..9 | sort {Get-Random})[0..8] -join ”
      PS C:\> $Password
      _bK{a-k0Z
      PS C:\>

  7. First, thank you. Second, do you need the “+ 0..9”? I see numbers in the char[33] to char[95] section. I guess it increases the chance for a number to be included.

    1. Joe–you are right. 0-9 are included in the earlier [char] ranges. I included it again, though, since the problem I found is that if you’re using any password complexity filters, it was occasionally possible to generate a password that only included letters. Once you introduce those extra 10 digits, the probability of you generating a password that the system won’t accept is much lower.

      Maybe there’s a slick way to create a one-liner that pulls “n” number of characters from various character groups to ensure complexity rules are matched?

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