4 ms·
They accidentally used the example key from AES-CMAC RFC, the full details are in the accompanying blog post: https://bughunters.google.com/blog/542484235747328
by taviso 2y ago
They accidentally used the example key from AES-CMAC RFC, the full details are in the accompanying blog post: https://bughunters.google.com/blog/5424842357473280/zen-and-the-art-of-microcode-hacking https://bughunters.google.com/blog/5424842357473280/zen-and-...
- timewizard 2y agoTaking "never roll your own" too far.
- deleted 2y ago[deleted]
- RachelF 2y agoYikes! One would have expected a little more code review or a design review from a hardware manufacturer, especially of security system. A system that people have been worried about since the Pentium FDIV bug. I guess this one just slipped through the cracks?
- garaetjjte 2y agoI suppose the reuse wasn't accidental, but they mistakenly thought the key doesn't matter for CMAC.
- bmenrigh 2y agoI feel like using the example key isn’t really the big failure here. They didn’t need a keyed hash at all, they needed a collision resistant hash. SHA256 would have eliminated this vuln and it has a hardcoded “key” built into it. Using a secret key for CMAC would not have been more secure, it would have just meant sophisticated hardware extraction of the key was required before this attack could be mounted.