"Freedom is slavery" and "Ignorance is strength" - What kind of rhetorical strategy is this?

Orwell's post-1945 writings (Animal Farm and 1984), are powerful allegories on the totalitarianism of the then recent decades. There was general scepticism concerning the possible shape of the political future. His slogans (of which All animals are equal, but some are more equal than others is perhaps the most famous) satirised those of the great dictators, not only the Soviet ones but those of the Third Reich, such as Arbeit macht frei ('work makes you free'.) written above the entrance gates of places like Auschwitz.

In 1984 Orwell attempts to show how public opinion is managed through the deft use of description in the names of government departments . The War Ministry is The Ministry of Peace, the Secret Police headquarters with its departmental torture chambers is The Ministry of Love, and the Information Ministry is The Ministry of Truth -where they only tell lies etc.

This is the Art-Deco, 1930s built Senate House, the administrative HQ of the University of London, in Bloomsbury.

During the Second World War, the building's use by the Ministry of Information inspired two works of fiction by English writers. The earliest, Graham Greene's novel The Ministry of Fear (1943), inspired a 1944 film adaptation directed by Fritz Lang set in Bloomsbury.[2] The description of the Ministry of Truth in George Orwell's novel Nineteen Eighty-Four (1949) matches the Senate House. His wife Eileen worked in the building for the Censorship Department of the Ministry of Information. Wikipedia.

I can never enter the building without sensing the sinister presence of Big Brother.

So the name of the rhetorical strategy I would suggest is (and I confess I am no rhetorician) satirical allegory.

This sounds like classic newspeak to me.

It seems to be an example of the big lie technique - a lie so "colossal" that no one would believe that someone "could have the impudence to distort the truth so infamously.". It also edges on the famous quote [mis]attributed to Joseph Goebbels: If you repeat a lie often enough, people will believe it, and you will even come to believe it yourself..

The exaggeration and boldness of these obviously untrue statements highlight how strong the influence of the Party and how complete the lack of any resistance at that point was. Some claims found in North-Korean propaganda of the modern day, e.g. the semi-miraculous stories surrounding the birth and childhood of the country's leaders, are actually not far from Orwell's wildest phantasies.