[gh02t]

Generating a shared sequence of random numbers is the basis of zero knowledge proofs, hence it could be useful for authentication. I can think of one interesting feature this scheme would have, if we assume the numbers from GPS are truly random. If you know the shared secret then you can predict the output as far back in time as you want, but you can't predict more than a day ahead.

[viraptor]

> Generating a shared sequence of random numbers is the basis of zero knowledge proofs

Could you give an example? The zero knowledge proofs I know are of the type: here's an X, tell me f(secret, X) - which doesn't require any shared information (apart from the secret you're verifying).

[gh02t]

It'd be more correct to say pseudorandom. The way I was taught ZKPs was in terms comparing the output of pseudorandom number generators seeded by a challenge and a shared secret, but you can also explain it in terms of hash functions instead.

What I was thinking was that the random number from GPS (or some sequence derived from it) could serve as the challenge, basically akin to a 2FA scheme like HOTP. Or a variety of other schemes, hinging on the trait that you can't predict the next output of the random number from GPS.