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by exabrial 2447 days ago
Great writeup. Once again, physical access owns. This line stuck out:

> The attack required 11000 signatures

For a smartcard, this seems rather impractical in the real world. My Nitrokey has 1938 total signs after a month of usage, signing every git commit to our company repository and using it to authenticate over ssh (gpg-agent)

1 comments

We are working on lowering that number :)

It is quite a conservative estimate, we didn't want to claim something our PoC couldn't deliver. Also, it is with minimal attack runtime, as in, after you have those signatures and timings it takes a few minutes to get the private key. There is a trade-off where you can get around some of the noise and thus need less signatures if you just throw more computation resources at it.