Random Challenges and Their Results are Stored and Sent to Host

[WilfredTA]

This makes the PoR answer unpredictable and variable. Challenges cannot be reused.

Benefits of this method:

1. Higher degree of confidence in audit accuracy: if the host passes, we can be more confident that they have the file.

Cons of this method:

1. Introduces an O(number of audits) space complexity for the data owner
2. Places an upper bound on the number of audits a data owner can do (they will have to download and re-upload the file if they run out of audits, which is more costly)
3. It is computationally costly for the data host, who has to process the entirety of the file data for each audit