Re: fun with nonces

On 7/5/2024 1:46 PM, Stefan Claas wrote:

Chris M. Thomasson wrote:

On 7/4/2024 10:47 AM, Stefan Claas wrote:

Let's assume Bob travels a lot and he wishes to
communicate encrypted with Alice, while using an
encryption program which uses a nonce as additional
input parameter.
>
He does not need to send Alice the nonces, once he
arrived, because they both have a shared secret.
Alice and Bob can generate them by themselves, no
matter what timezone they are in and the nonces will
be random and can be re-generated with the same values
again, per day.
>
https://github.com/stefanclaas/nfs
>
I Have to do a README which explains this scenario
a bit. Hope you like the idea!
>

>
Hopefully the nonces were created by a TRNG such that they cannot be
repeated expect by pure chance... Fair enough?
>
Every PRNG has a period and a way to set the starting point.

 Well, they can be also pseudo-random. Mine are deterministic,
based on a passphrase and date while using hkdf.
 

Can somebody try to get at things where they can gain educated guesses at your schedule, so to speak?