This has been bothering me, a lot. Google talks [1] about how Passkey replication is e2e encrypted between devices, but AFAICT they're just using a pin + key derivation. A six digit pin is like 20 bits of entropy before a KDF. [2]
Has anyone seen any docs that might help characterize how much entropy the keys have for e2e encryption (Android/iOS)?
I must be missing something, because I can't see how Google would call something e2e encrypted if the keys only have like 30-35 bits of "effective" entropy after a KDF. But that seems like it's the case??
[1] "From the user's point of view, this means that when using
a passkey for the first time on the new device, they will
be asked for an existing device's screen lock in order to
restore the end-to-end encryption keys"
Has anyone seen any docs that might help characterize how much entropy the keys have for e2e encryption (Android/iOS)?
I must be missing something, because I can't see how Google would call something e2e encrypted if the keys only have like 30-35 bits of "effective" entropy after a KDF. But that seems like it's the case??
[1] https://security.googleblog.com/2022/10/SecurityofPasskeysin...[2] https://www.omnicalculator.com/other/password-entropy?c=SGD&...