Canton Daml Authorization

Overview

Daml is built for mutually distrusting parties: templates and choices guarantee nobody can cheat. Authorization is declarative (no msg.sender) and enforced at the protocol level. This skill covers the formal model and the workflow patterns that satisfy it.

The core problem: who must sign?

A contract signed only by its issuer is unsafe for the owner — the issuer could archive it unilaterally. To give the owner guarantees, add them as a signatory:

template Iou
  with
    issuer : Party
    owner : Party
    cash : Cash
  where
    signatory issuer, owner          -- both authorities required