The authors actually noticed doing only rotation would be easy to attack, this is why they added matrices A1 and A2. However, as it turns out, `A1/|A1|` and `A2/|A2|` are rotation matrices. Then we can describe A1 and A2 as rotation matrices multiplied by some scalar value: `A1 = k1 rot(λ1)` and `A2 = k2 rot(λ2)`.
**[Original write-up](https://github.com/epicleet/write-ups/blob/master/2019/hxp_36c3/peerreviewed/README.md)**