You can use TXT lookups to get data in to an organisation.

You can use the following PowerShell scripts to convert Base64 into Binary.

$plainText = "Hello World"
$sanitisedPlainText = [System.Text.Encoding]::UTF8.GetBytes($plaintext)
$base64Text = [System.Convert]::ToBase64String($sanitisedPlainText)
$base64Text
$newPlainText = [System.Convert]::FromBase64String($base64Text)
$newSanitisedPlainText = [System.Text.Encoding]::UTF8.GetString($newPlainText)
$newSanitisedPlainText