Consensus Trust Root

The ROFL app example already contains an embedded root of trust called the consensus trust root. The preconfigured trust root is valid for the current deployment of Sapphire Testnet. This chapter briefly describes what the trust root is, how it can be securely derived and configured in your ROFL app.

The Root of Trust

In order to ensure that the ROFL app can securely authenticate it is talking to the actual consensus layer and not a fork, you need to configure it with a suitable consensus trust root. The trust root is a well-known consensus block header that is used to bootstrap the light client which verifies everything else.

Having a correct trust root configured makes it impossible even for the node operator who is running your ROFL app to forge any queries as integrity of all results is verified against the consensus layer trust root. One should try to use a somewhat recent trust root which can be refreshed during application upgrades.

caution

The consensus trust root represents the root of security for the ROFL app. Not configuring it makes your application vulnerable to man-in-the-middle attacks by the node operator.

Embedding the Root

In order to obtain a suitable consensus trust root you can leverage the Oasis CLI as follows (note the correct network and paratime). Note that you should use a node you trust to query this information (the example below uses the default public gRPC endpoints).

oasis rofl trust-root --network testnet --paratime sapphire

Which should output something like the following:

TrustRoot {
    height: 22110615,
    hash: "95d1501f9cb88619050a5b422270929164ce739c5d803ed9500285b3b040985e".into(),
    runtime_id: "000000000000000000000000000000000000000000000000a6d1e3ebf60dff6c".into(),
    chain_context: "0b91b8e4e44b2003a7c5e23ddadb5e14ef5345c0ebcb3ddcae07fa2f244cab76".to_string(),
}

You can then use this in your ROFL app definition by adding the following method to your App trait implementation.

fn consensus_trust_root() -> Option<TrustRoot> {
    Some(TrustRoot {
        height: 22110615,
        hash: "95d1501f9cb88619050a5b422270929164ce739c5d803ed9500285b3b040985e".into(),
        runtime_id: "000000000000000000000000000000000000000000000000a6d1e3ebf60dff6c".into(),
        chain_context: "0b91b8e4e44b2003a7c5e23ddadb5e14ef5345c0ebcb3ddcae07fa2f244cab76"
            .to_string(),
    })
}