CBTF · Module 2 of 5 · 12 min

Quorum certificates and offline receipts

A quorum certificate is a set of 2f + 1 signed votes for the same digest at the same sequence. Anyone holding the replicas' public keys can verify it offline.

Quorum-QaaS sells exactly this: send the SHA-256 digest of a record, get back the replicas' Ed25519-signed votes as a receipt. The record itself never leaves the customer.

Consensus orders and notarizes. It cannot make an unauthorized action authorized.

Key points

QC = 2f + 1 signed votes on one digest.
Verifiable offline with replica keys.
Only digests leave the customer.
Consensus notarizes, never authorizes.

In the CAIN-42 codebase

scripts/cain42_bft/verify_qaas_receipt.py — standalone receipt verifier
scripts/cain42_bft/verify_pbft_qc_bundle.py — QC bundle verifier

▶ Notarize a record live

Practice check

Practice 1 · choose one

What does a Quorum-QaaS customer send?

Practice 2 · true or false

Quorum certificates and offline receipts

Key points

In the CAIN-42 codebase

Practice check

What does a Quorum-QaaS customer send?

“A quorum certificate can authorize a denied action.”