I am implementing a system using some sort of 32bytes OTC (One-Time Code) and signing it with ECDSA to get verification of a public key owner.
The key I'm using is
Since the nature of this mechanism is very short-lived (say I will refresh the OTC within 1 minute), I doubt whether I can shorten the OTC in some sense that it still gives acceptable security.
Therefore I would like to know the following as a direction to measure the security strength:
- The probability of best attack known to
secp256r1key per trial, with variable "length of the message-to-be-signed"
- The expected number of trials to make expected value of success = 1
I'm okay if you just refer some papers or guidance and not doing the calculation here; or any other direction of such measurement.