Get Encryption Key

Get-EncryptionKey.ps1

function Get-EncryptionKey()
{
  <#
    .SYNOPSIS
    Retrieves a 128/192/256-bit encryption key using the given keyphrase.
    
    .PARAMETER KeyPhrase
    Specifies the phrase to use to create the 128-bit key.
    
    .PARAMETER Length
    Specifies the number of bits to make the length.   Use either 128, 192, or 256 bits.  Default is 128.

    .OUTPUTS
    [byte[]]
    Returns a 128/192/256-bit (32/48/64-byte) array that represents the keyphrase.
    
  #>
  [CmdletBinding()]
  param
  (
    [Parameter(Mandatory=$true,Position=0,ValueFromPipeline=$true)] 
    [string] $KeyPhrase,

    [ValidateSet(128,192,256)] [int] $Length = 128
  )
    
  process
  {
    $enc = [System.Text.Encoding]::UTF8;
    
    $bytes = $Length / 4;
    $KeyPhrase = $KeyPhrase.PadRight($bytes, "0").SubString(0,$bytes);
    $enc.GetBytes($KeyPhrase);
  }
}