Powershell script to convert a binary file to/from a base64 text file

convert_binary_file_to_base64.ps1

Param(
	$filePath,
	[switch]$reverse = $false
)

## Usage
#
# From binary to UTF8 base-64 file with "b64" extension:
#     .\convert_binary_file_to_base64.ps1 path\to\file.bin
#
# From UTF8 base-64 file back to binary:
#     .\convert_binary_file_to_base64.ps1 -reverse path\to\file.bin.b64
#
# Update (20241010): Add compatibility with PowerShell major versions >5, increase conversion speed with "-Raw" arg.
##

$base64ext = ".b64"
$encodingArg = if ([int](Get-Host).Version.Major -gt 5) {@{AsByteStream = $true}} else {@{Encoding = "Byte"}}

if ($reverse)
{
	$contentString = Get-Content $filePath -Encoding UTF8
	$binary = [Convert]::FromBase64String($contentString)
	$originalFileName = ($filePath -split $base64ext)[0]
	$ext = [IO.Path]::GetExtension($originalFileName)
	$filenameWithoutExt = [IO.Path]::GetFileNameWithoutExtension($originalFileName)
	$parentDir = [IO.Path]::GetPathRoot($originalFileName)
	$unixTimeStamp = [DateTimeOffset]::UtcNow.ToUnixTimeSeconds()
	$newFileName = ("{0}{1}{2}{3}{4}" -f $parentDir, $filenameWithoutExt, ".", $unixTimeStamp , $ext)
	Set-Content -Path $newFileName -Value $binary @encodingArg
}
else
{
	$contentBytes = Get-Content $filePath -Raw @encodingArg
	$base64 = [Convert]::ToBase64String($contentBytes)
	Set-Clipboard -Value ($base64).ToString()
	Set-Content -Path ("{0}{1}" -f $filePath, $base64ext) -Value $base64
}

Also copies the base-64 contents to the clipboard when converting to a base-64 file.

Thanks for sharing the combination of encodings that makes this work without tacking on extra characters like it did when I tried.
I wrapped this in a function and added a line after 28 to print the generated file name to stdout so I can pipe that filename to another script. I'm guessing there's a more elegant 'idiomatic Powershell' way of doing that but I'm more familiar with Bash (where base64 encoding and decoding is commonly available and simple).

thanks a lot

Powershell Core no longer knows about the Byte encoding .
->
Set-Content -Path $newFileName -Value $binary -AsByteStream

@janv8000 Updated; thanks for letting me know. Looks like only PowerShell Core 6.2.3 was out when I originally wrote it, and it definitely wasn't on my radar yet. 😅 Is now, though!