Canton Privacy Model

Overview

Most blockchains buy integrity with global visibility — every validator sees every transaction. Canton resolves the integrity-vs-privacy tension with sub-transaction privacy: a transaction is decomposed into views, and each party sees only the parts it's entitled to. Other parts reveal no payload and no metadata (not even which parties/participants are involved). The synchronizer sees only encrypted messages and confirmation results.

How it works

For a multi-party transaction, Canton does not send the whole transaction to everyone:

1. Decomposition — split into views by stakeholder relationships.
2. Encryption — each view encrypted to its recipients.
3. Distribution — synchronizer delivers only entitled views.
4. Validation — each participant validates its view independently.
5. Confirmation — participants confirm based on their view alone.

Example ("Alice pays Bob, Bob pays Charlie"): Alice sees only her payment to Bob; Bob sees both (he's in both); Charlie sees only his receipt — not Alice's involvement or the source of funds.

The two visibility rules

1. You see actions you have a stake in. Signatories always see the contract and all events on it; observers see it by explicit declaration; controllers see the choices they can exercise.
2. If you see an action, you see its consequences. You see the creates/archives it produces — which lets you independently verify the action was executed correctly.