As noted by userbinator: https://news.ycombinator.com/item?id=49220030
Not a backdoor, but a documented CPU feature.
The whitepaper about rosenbridge cannot be published because it would constitute scientific fraud.
Calling it a "backdoor" is subjective, because it looks enough like an unintentional exploitable bug that one could make that argument. Is an accidental backdoor still a backdoor? That's pure semantics.
> Not a backdoor, but a documented CPU feature.
I would be even more explicit and call it “Not a backdoor, but a documented feature of ancient de facto unused Via C3 CPU.”