  SAFE is a data-centric platform for building multi-domain networked systems,
i.e., systems whose participants are controlled by different principals.
Participants make trust decisions by issuing local queries over logic content
exchanged in certificates. The contribution of SAFE is to address a key barrier
to practical use of logical trust: the problem of identifying, gathering, and
assembling the certificates that are relevant to each trust decision.
  SAFE uses a simple linking abstraction to organize and share certificates
according to scripted primitives that implement the application's trust kernel
and isolate it from logic concerns. We show that trust scripting with logical
data exchange yields compact trust cores for example applications: federated
naming, nested groups and roles, secure IP prefix delegation and routing,
attestation-based access control, and a federated infrastructure-as-a-service
system. Linking allows granular control over dynamic logic content based on
dependency relationships, enabling a logic server to make secure inferences at
high throughput.
