Isn’t propaganda just a form of persuasion? What about propaganda separates it from advertising or interpersonal communication?
Edit: Not all propaganda involves lying. For some reason, we seem to be more comfortable with a person lying to us than we are with viewing a propaganda poster that uses verifiable facts.
Edit 2: Another interesting note is that in some countries, propaganda is not viewed negatively like it is in English speaking countries.
Dictionaries seem to disagree with your definition.
Wiktionary suggests lying isn’t necessary:
It’s very similar to the OED definition returned from Google.