I don’t see it suggest anywhere that you know which particular input is part of the back door input set. I think you just have to identify which inputs are attacks and which are not.
I believe synthesizing a back door set falls within the Trojan horse problem and could be very hard as the back door set may just be random numbers. If you can synthesize the back door set you can probably solve the Trojan horse problem.
I don’t see it suggest anywhere that you know which particular input is part of the back door input set. I think you just have to identify which inputs are attacks and which are not.
I believe synthesizing a back door set falls within the Trojan horse problem and could be very hard as the back door set may just be random numbers. If you can synthesize the back door set you can probably solve the Trojan horse problem.