CAIN-42 CAIN StudioCFVE · Module 3 of 5 · 11 min
Proof-carrying actions and code
A proof-carrying action ships with evidence that it satisfies policy, which the receiver checks cheaply instead of trusting the sender.
In CAIN, proofs are bound to the exact action by hash: change any parameter and the proof no longer matches.
The receiver verifies; it never assumes. A missing or mismatched proof is a refusal.
Key points
- Ship the proof with the action.
- Bind proof to action by hash.
- Missing/mismatched proof = refuse.
In the CAIN-42 codebase
cain/cain_proof_carrying_code.py— proof-carrying codeactionproof/— ActionProof
Practice check
Practice 1 · choose one
A parameter changes after the proof was made. The proof…
Practice 2 · true or false