Identities & Policies

Identities and Policies are the foundation of nXCC’s security model. They provide a verifiable, on-chain root of trust for all off-chain operations, ensuring that only authorized workers can access sensitive data and perform actions.

Identities: On-Chain Root of Trust

An nXCC Identity is a standard ERC-721 NFT deployed on an EVM-compatible blockchain. This provides several key advantages:

• Ownership: Each identity has a clear owner, which can be an Externally Owned Account (EOA) or a smart contract like a multisig or DAO.
• Verifiability: Anyone can verify the existence and ownership of an identity on-chain.
• Composability: As a standard NFT, identities can be managed with existing wallets, marketplaces, and smart contract tooling.

The core of the identity is the Identity.sol smart contract. Its most important function is setPolicyURL, which allows the owner of the NFT to set its tokenURI. In nXCC, this URI points directly to the Policy that governs the identity.

Managing Identities

You can manage identities using the @nxcc/cli or any standard smart contract interaction tool like Foundry’s cast.

Example: Transferring an Identity with cast

# Assuming environment variables are set
cast send $IDENTITY_CONTRACT_ADDRESS "safeTransferFrom(address,address,uint256)" \
  $OWNER_ADDRESS $RECIPIENT_ADDRESS $IDENTITY_ID \
  --private-key $SIGNER_PK --rpc-url $RPC_URL

Policies: Programmable Access Control

A Policy is a special type of worker that acts as a programmable gatekeeper for an Identity’s secrets. When a process (like another worker) wants to access an identity’s secrets, an nXCC node fetches the policy from the URL stored on-chain and executes it inside a secure TEE.

How Policies Work

A policy is a stateless worker that must implement a fetch handler. It receives a POST request containing a JSON array of PolicyExecutionRequest contexts. For each context, it must return a boolean decision (true for allow, false for deny).

Example: A Simple Allow-All Policy

This policy approves every request it receives.

policy.ts

export default {
  async fetch(request: Request): Promise<Response> {
    if (request.method !== "POST") {
      return new Response("Invalid method", { status: 405 });
    }
    try {
      const contexts = await request.json();
      if (!Array.isArray(contexts)) {
        return new Response("Expected an array of contexts", { status: 400 });
      }
      // This is a simple allow-all policy. It returns `true` for every request.
      const decisions = contexts.map(() => true);
      return new Response(JSON.stringify(decisions), {
        headers: { "Content-Type": "application/json" },
      });
    } catch (e) {
      return new Response("Invalid JSON payload", { status: 400 });
    }
  },
};

The PolicyExecutionRequest Context

The real power of policies comes from the context they receive. The PolicyExecutionRequest object contains verifiable information about the requester that the policy can use to make a decision.

• secret_ids: An array of SecretIds being requested.
• consumer: Information about the worker requesting access, including the hash of its code bundle (bundle_hash).
• env_report: The TEE attestation report from the node making the request. This report cryptographically proves that the requester is running genuine nXCC software in a secure, un-tampered environment.

Example: An Attestation-Based Policy

A more secure policy would inspect the env_report to ensure the request is coming from a trusted TEE.

// A more secure policy that checks the TEE measurement.
export default {
  async fetch(request: Request): Promise<Response> {
    const contexts: PolicyExecutionRequest[] = await request.json();

    const TRUSTED_MEASUREMENT = "0x..."; // The expected TEE measurement hash

    const decisions = contexts.map((ctx) => {
      // Check if the requester's TEE measurement matches our trusted value.
      return ctx.env_report.attestation.measurement === TRUSTED_MEASUREMENT;
    });

    return new Response(JSON.stringify(decisions));
  },
};

By combining on-chain identity NFTs with off-chain, TEE-executed policy workers, nXCC provides a flexible and powerful framework for building secure, decentralized applications.