Yeah, https://lwn.net/Articles/762152/ has a full source code to Speck. It's like - OK, where is the backdoor, is eight the backdoor, or is three? Did the NSA sneak a backdoor into the idea of binary arithmetic when that was invented?
If people want to pick fights with the NSA, fine, but this may have been the dumbest possible fight to pick.
How does the implementation of HPolyC look in terms of whether I would notice if you hid something naughty in there?