Read file, gzip and convert to base64.

read-file-gzip-base64.ps1

$filepath = "/etc/passwd"
$fs = New-Object IO.FileStream($filepath, [System.IO.FileMode]::Open)
$ms = New-Object System.IO.MemoryStream;
$gzs = New-Object System.IO.Compression.GzipStream($ms, [System.IO.Compression.CompressionMode]::Compress);
$fs.CopyTo($gzs);
$fs.Close();
$gzs.Close();
$ms.Close();

[System.Convert]::ToBase64String($ms.ToArray());