Cruel Summer: hybrid signatures, Downfall, Zenbleed, 2G downgrades

We're back from our summer vacation! We're covering a bunch of stuff we saw and did:

Transcript: 
https://securitycryptographywhatever.com/2023/09/13/cruel-summer/

Links:
- Zenbleed: https://lock.cmpxchg8b.com/zenbleed.html
- Downfall: https://downfall.page
- Post-quantum Yubikeys: https://security.googleblog.com/2023/08/toward-quantum-resilient-security-keys.html

"Security Cryptography Whatever" is hosted by Deirdre Connolly (@durumcrustulum), Thomas Ptacek (@tqbf), and David Adrian (@davidcadrian)