This is interesting. As someone who's been reading literature related to WebAuthn and FIDO2, I was very much curiously looking at various vault designs that sto

This is interesting. As someone who's been reading literature related to WebAuthn and FIDO2, I was very much curiously looking at various vault designs that stored secrets away (either ed-dsa identity subkeys or 25519-dh encryption subkeys) other than in FIDO2-certified server-vaults or user-held FIDO2 keys. From among the designs that looked decent to my untrained eye (not a cryptographer) were that of Apple's and Signal's [0]. The thing they had in common was they wanted to gatekeep attempts to brute-force (one half of the) the secret they stored on behalf of the user, via either binding them in HSMs or secure enclaves. Keybase instead do what they call TripleSec [1], which seems like a cheaper solution compared to Apple's / Signal's, and relies on multi-cipher encryption scheme to thwart brute-force attempts. One area that I've been increasingly looking at is OPRF (Oblivious Pseudo Random Functions) [2] and the use-cases it may enable, especially in replacing the HSMs or secure enclaves whilst retaining similar properties against brute-force attacks. [0] https://news.ycombinator.com/item?id=21838413 https://news.ycombinator.com/item?id=21838413 [1] https://keybase.io/triplesec https://keybase.io/triplesec [2] https://blog.cloudflare.com/opaque-oblivious-passwords/ https://blog.cloudflare.com/opaque-oblivious-passwords/