Quickie: Powershell Base64 and Base64URL encoding and decoding functions

 

function Base64Encode ( $s)

{

    return [System.Convert]::ToBase64String([System.Text.Encoding]::UTF8.GetBytes($s))

}

function Base64Decode ( $s)

{

    return [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($s))

}

function Base64URLEncode ( $s)

{

    $s = $s.Split('=')[0] #Remove trailing '='s

    $s = $s.Replace('+','-');

    $s = $s.Replace('/','_');

    return Base64Encode ($s) 

    # Thanks https://stackoverflow.com/a/33113820/7834195

}

function Base64URLDecode ($s)

{

    $s = $s.Replace('-','+');

    $s = $s.Replace('_','/');

    switch ($s.Length % 4) #// Pad with trailing '='s

    {

        0 { break } # No pad chars in this case 

        2 { $s+='=='; break } # Two pad chars

        3 { $s+='='; break; } # One pad char

        Default { throw "Illegal base64url string!" }

     }

    #[string]$stringToEncode=$text

    $return = Base64Decode($s)

    return $return

    # Thanks https://stackoverflow.com/a/33113820/7834195

}