I learned the other day that FIDO2 keys have a counter so that if an attacker does manage to clone the key, and both keys continue to be used, the counter for them will desync and the server can detect the clone.
Pretty cool, wonder how that plays out in practice.
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Like I'm pretty sure the recommendation is allow for two keys but AWS still doesn't, so I'm a bit doubtful that the average backend is detecting/ handing this, but I'm certainly curious to hear otherwise.
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Should allow for more than 2 keys since adding more keys is the best way to offer recovery.
My Google account has 3 security keys: YubiKey 5, Trezor Model T and Pixel 5 Titan M.
Can restore Trezor by fetching 2/3 Cryptosteel backups and setting the 2FA counter to Unix time.
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So in this case (with Trezor) you're cloning the seed/ counters across devices? I'm not super familiar with that system.
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Trezor generates a high entropy seed as a BIP39 seed phrase (they created the standard) and has you write it down or physically store it via an approach like cryptosteel.com and enter it again to confirm.
You only need the seed phrase to recovery if it's broken or lost.
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Most sites don't even allow you to have security keys as the only 2FA mechanism. My Google account is opted into the Advanced Protection Program so it's the only option. It's quite important since it's my domain registrar and OVH recovery email.
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Yeah, we SSO through Google and enroll every employee to APP + we use Context Aware Access to tie sessions to Chromebooks (presumably via titan key).
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