How can I base64 encode a string on linux so it matches windows "Unicode.GetBytes.ToBase64String"?

Question

This question probably has been answered, but I couldn't find it

Question

How can I 'base64 encode' a string in bash so it matches "what windows expects", i.e. "Unicode.GetBytes.ToBase64String"

Context

The powershell help text has this example

$command='dir'
$bytes = [System.Text.Encoding]::Unicode.GetBytes($command)
$encodedCommand = [Convert]::ToBase64String($bytes)
echo $encodedCommand
powershell.exe -encodedCommand $encodedCommand

Windows Output

The encoded output is this:

ZABpAHIA

Very Different results on linux

If I do the same thing on linux, I get this:

echo "dir" | base64
ZGlyCg==

Encodings?

I've tried using "iconv" to convert encodings, but no luck, i.e same results.

echo dir |iconv -f ASCII -t UTF-8 |base64

Differences

So you can see two differences:

• Alphanumeric characters differ
• Trailing "===" appears on linux

Solution

Unicode in Powershell is UTF16 LE, not UTF8.

Unicode: Encodes in UTF-16 format using the little-endian byte order.

Source: Set-Content for FileSystem

I don't use linux, but if your utf8-sample above works, then you could try:

iconv -f ASCII -t UTF-16 mycmd.txt |base64

If you plan to bring a string encoded in Powershell into Linux then do the following, first encode in Powershell

$string = "That's no moon!"
[system.convert]::ToBase64String([System.Text.Encoding]::unicode.getbytes($String))

VABoAGEAdAAnAHMAIABuAG8AIABtAG8AbwBuACEA

Then in Linux do the following:

echo VABoAGEAdAAnAHMAIABuAG8AIABtAG8AbwBuACEA | base64 -d | iconv -f utf-16 -t utf-8; echo

That's no moon!