Following your suggestion, I went ahead and modified the scrambling formula. The crux of the problem is that the secret is allowed to be absolutely anything (it

Following your suggestion, I went ahead and modified the scrambling formula. The crux of the problem is that the secret is allowed to be absolutely anything (it's user provided). As a consequence, it's a bad idea to depend on it for the multiplier. Now, the secret key only function is to be a mask, while the multiplier is under implementation control, guaranteeing a good prime.