Zen and the Art of Microcode Hacking
bughunters.google.com
3 threads
> We noticed that the key from an old Zen 1 CPU was the example key of the NIST SP 800-38B publication (Appendix D.1 2b7e1516 28aed2a6 abf71588 09cf4f3c) and was reused until at least Zen 4 CPUs.
Oops!
> AMD Zen CPUs use an almost standard RSASSA-PKCS1-v1_5 algorithm; however, instead of using one of the recommended hash functions, an alternative that is prone to collisions was selected.
[Etc.]
Sounds like Yet Another Fail for DIY Crypto.
This is really interesting just for the details on the microcode mechanisms inside the chip (and there's a link to similar research on Intel chips.)