@dangoodin "To uncover the side channel, the researchers reverse-engineered the Infineon cryptographic library, a heavily fortified collection of code that the manufacturer takes great pains to keep confidential." Security through obscurity. If I remember correctly Tropic Square commented on this when they were launching their effort to develop a open and transparent security chip. I'll try to find that blog post.
@dangoodin Here it is https://blog.trezor.io/introducing-tropic-square-why-transparency-matters-a895dab12dd3 the chapter I am referring to is "Our Dive into Secure Element, NDA chips and how we broke them"