Похоже на работу base64
$text_file = "C:\Temp\1.bin.txt"
$bin_file = "C:\Temp\1.bin"
# binary -> text
[io.file]::WriteAllText($text_file, [Convert]::ToBase64String([io.file]::ReadAllBytes($bin_file)))
# text -> binary
[io.file]::WriteAllBytes($bin_file, [System.Convert]::FromBase64String([io.file]::ReadAllText($text_file)))