zstr+secstr.ps1

function encode($s){
    return $s | ConvertTo-SecureString -AsPlainText -Force | ConvertFrom-SecureString
}

function decode($s){
    $SecureString = $s | ConvertTo-SecureString
	  $BSTR = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($SecureString)
	  $PlainString = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto($BSTR)
    return $PlainString
}

function zstr($s) {
    $data = [System.Text.Encoding]::UTF8.GetBytes($s)
    $ms = New-Object IO.MemoryStream
    $msd = New-Object IO.MemoryStream
    $ms.Write($data, 0, $data.Length)
    $ms.Seek(0,0) | Out-Null
    $cs = New-Object IO.Compression.GZipStream($msd, [IO.Compression.CompressionMode]::Compress)
    $ms.CopyTo($cs)
    $ms.Close()
    $cs.Close()
    return [System.Convert]::ToBase64String($msd.ToArray())
}

function unzstr($s) {
    $data = [System.Convert]::FromBase64String($s)
    $ms = New-Object IO.MemoryStream
    $msd = New-Object IO.MemoryStream
    $ms.Write($data, 0, $data.Length)
    $ms.Seek(0,0) | Out-Null
    $cs = New-Object IO.Compression.GZipStream($ms, [IO.Compression.CompressionMode]::Decompress)
    $cs.CopyTo($msd)
    $ms.Close()
    $cs.Close()
    $msd.Close()
    return [System.Text.Encoding]::UTF8.GetString($msd.ToArray())
}

function Compress-String {
    param (
        [Parameter(Mandatory=$true)]
        [string]$inputString
    )

    $compressedString = ""

    $charCount = 1
    $prevChar = $inputString[0]

    for ($i = 1; $i -lt $inputString.Length; $i++) {
        $currentChar = $inputString[$i]

        if ($currentChar -eq $prevChar) {
            $charCount++
        }
        else {
            if ($charCount -ge 3) {
                $compressedString += "$prevChar{$charCount}"
            }
            else {
                $compressedString += [string]$prevChar * $charCount
            }

            $charCount = 1
            $prevChar = $currentChar
        }
    }

    if ($charCount -ge 3) {
        $compressedString += "$prevChar{$charCount}"
    }
    else {
        $compressedString += [string]$prevChar * $charCount
    }

    return $compressedString
}

function Decompress-String {
    param (
        [Parameter(Mandatory=$true)]
        [string]$compressedString
    )

    $decompressedString = ""

    $i = 0
    while ($i -lt $compressedString.Length) {
        $currentChar = $compressedString[$i]

        if ($currentChar -ne "{" -and $currentChar -ne "}") {
            $decompressedString += $currentChar
            $i++
        }
        elseif ($currentChar -eq "{") {
            $endIndex = $compressedString.IndexOf("}", $i)
            $substring = $compressedString.Substring($i + 1, $endIndex - $i - 1)
            $repeatCount = [int]$substring - 1

            $decompressedString += [string]$compressedString[$i - 1] * $repeatCount

            $i = $endIndex + 1
        } else {
            $i++
        }
    }

    return $decompressedString
}