Your challenge is to keep Algeria an integral part of France, with a POD no earlier than 1945.
Hard. Very hard. Had the POD-limitation been five years earlier, I could have an idea of how to do it (or, at least, how to make it less hard), but with 1945...
Canaris's idea would have the problems that France's legimatacy would be hit hard by such an event, and the Algerian independence movement was already too strong at this point (even with very harsh methods, clearing out partisans perpetually from an area with a population sympathetic to them, and parts of it with a geography good for hiding, isn't exactly the easiest thing: and even military leaders would probably balk at committing genocide against the Arabs). Basically, De Gaulle thought he couldn't keep Algeria in France: he was too much of a nationalist to grant them independence otherwise, and I'm inclined to agree with him.
The military coup would result in Algeria being a part of France longer, granted, but other things will go downhill for France, and sooner or later they would either have to drop Algeria, or face
severe problems.
And given that the OP implies that it should persist to 'present date', I don't think that's enough

.