Powershell AD PW Changer

#*=============================================================================
#* Script Name: adpwchange2014.ps1
#* Created: 2014-10-07
#* Author:
#* Purpose: This is a simple script that queries AD users.
#* Reference Website: http://theboywonder.co.uk/2012/07/29/executing-powershell-using-php-and-iis/
#*
#*=============================================================================

#*=============================================================================
#* PARAMETER DECLARATION
#*=============================================================================
param(
[string]$base64_username,
[string]$base64_newpassword,
[string]$base64_oldpassword,
[string]$rand
)

#*=============================================================================
#* IMPORT LIBRARIES
#*=============================================================================

if ((Get-Module | where {$_.Name -match "ActiveDirectory"}) -eq $null){
    #Loading module
    Write-Host "Loading module AcitveDirectory..."
    Import-Module ActiveDirectory
    }else{
    write-output "Error: Please install ActiveDirectory Module"
    EXIT
    NUL
    Stop-Process -processname powershell*
    }
#*=============================================================================
#* PARAMETERS
#*=============================================================================
$username = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($base64_username))
$newpassword = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($base64_newpassword))
$oldpassword = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($base64_oldpassword))

#*=============================================================================
#* INITIALISE VARIABLES
#*=============================================================================
# Increase buffer width/height to avoid PowerShell from wrapping the text before
# sending it back to PHP (this results in weird spaces).
$pshost = Get-Host
$pswindow = $pshost.ui.rawui
$newsize = $pswindow.buffersize
$newsize.height = 1000
$newsize.width = 300
$pswindow.buffersize = $newsize

#*=============================================================================
#* EXCEPTION HANDLER
#*=============================================================================

#*=============================================================================
#* FUNCTION LISTINGS
#*=============================================================================

    Function Test-ADAuthentication {
        Param($Auth_User, $Auth_Pass)
        Write-Output "Running Function Test-ADAuthenication"
        $domain = $env:USERDOMAIN

        Add-Type -AssemblyName System.DirectoryServices.AccountManagement
        $ct = [System.DirectoryServices.AccountManagement.ContextType]::Domain
        $pc = New-Object System.DirectoryServices.AccountManagement.PrincipalContext($ct, $domain)
        $pc.ValidateCredentials($Auth_User, $Auth_Pass).ToString()
        }

    Function Set-ADAuthentication{
        Param($Auth_User,$Auth_OldPass, $Auth_NewPass)
        Write-Output "Running Function Set-ADAuthenication"
        $domain = $env:USERDOMAIN
        $SecureString_NewPass = ConvertTo-SecureString $Auth_NewPass -AsPlainText -Force
        $SecureString_OldPass = ConvertTo-SecureString $Auth_OldPass -AsPlainText -Force
        #Running -whatif to simulate results
        #Therefore we expect "Failed: Validation of Password Change" as it was not changed
        Set-ADAccountPassword -Identity $Auth_User -NewPassword $SecureString_NewPass -OldPassword $SecureString_OldPass -PassThru

        $authentication = Test-ADAuthentication $Auth_User $Auth_NewPass
        if ($authentication -eq $TRUE) {
            Write-Output "Success:$rand Validation of Password Changed"
            }elseif ($authentication -eq $FALSE) {
            Write-Output "Failed:$rand Validation of Password Change"
            }else{
                Write-Output "Error: EOS"
                EXIT
                NUL
                Stop-Process -processname powershell*
                }
        }

#*=============================================================================
#* Function: function1
#* Purpose: This function does X Y Z
#* =============================================================================

#*=============================================================================
#* END OF FUNCTION LISTINGS
#*=============================================================================

#*=============================================================================
#* SCRIPT BODY
#*=============================================================================
Write-Output $PSVersionTable
Write-Output "  "
$authentication = Test-ADAuthentication "$username" "$oldpassword"
if ($authentication -eq $TRUE) {
    Set-ADAuthentication $username $oldpassword $newpassword
    }elseif ($authentication -eq $FALSE) {
    Write-Output "Failed:$rand Authentication"
    }else {Write-Output "Error: EOS"
    EXIT
    NUL
    Stop-Process -processname powershell*
    }

#*=============================================================================
#* SCRIPT Exit
#*=============================================================================
Write-Output "End Of Script"
EXIT
NUL
Stop-Process -processname powershell*