dsfx/docs/adr/0009-trust-access-control-and-replication-policies.md

# ADR-0009: Trust, Access Control, and Replication Policies

## Status

Proposed

## Context

Our system’s secure and resilient operation depends on how nodes establish trust, manage access, and enforce replication policies. Since users explicitly configure their node networks, trust is built on manually approved connections using public key credentials, ensuring that data sharing and replication occur strictly among verified peers (FR-4, FR-5). Further, robust access control mechanisms are essential to prevent unauthorized access while ensuring that all replication actions remain transparent and auditable (FR-6, NFR-1).

Given our focus on privacy and user control, the system must enforce policies that guarantee replication happens only within a set of trusted nodes and that access privileges can be granted or revoked as needed. These policies need to integrate seamlessly with our deterministic simulation testing framework to validate behavior under various adverse conditions (NFR-2, NFR-6).

## Decision

We will implement trust, access control, and replication policies with the following design principles:

- **Explicit Trust Management:**
  Trust is established based on user-approved connections. Each node connection is verified through public key authentication and explicit configuration by the user. No automatic trust propagation is allowed, ensuring that all participating nodes have been deliberately authorized.

- **Access Control Mechanisms:**
  The system will enforce access controls using cryptographic credentials. Each access request to file data or node resources must be signed and verified. Audit logs will capture every access grant or revocation, enhancing transparency and security in line with our auditability requirements (FR-6, NFR-1).

- **Automated Replication Within Trusted Networks:**
  Replication policies are enforced automatically within the user-configured network. The system continuously monitors the availability and integrity of file chunks, replicating data only among nodes that have been explicitly authorized by the user. This automated process is transparent to the user, ensuring that data remains available and consistent without manual intervention.

- **Policy Verification and Simulation:**
  The entire trust and access control mechanism is designed to be fully testable within our deterministic simulation framework. This will allow us to validate the performance and reliability of trust validation, access control, and replication policies under simulated network and disk failure conditions (NFR-2, NFR-6).

## Consequences

- **Advantages:**

  - **Enhanced Security:** Explicit trust management and strong cryptographic access controls ensure that only authorized nodes participate in data replication and file sharing, greatly reducing the risk of unauthorized access (FR-4, NFR-1).
  - **Transparent Operations:** All access and replication events are logged and auditable, reinforcing our commitment to transparency and enabling clear tracking of every file operation (FR-6, NFR-5).
  - **User-Centric Control:** By centralizing trust management in the hands of the user, the system upholds the principle of digital self-ownership and ensures that replication policies operate strictly within user-defined networks.

- **Trade-offs:**
  - **Increased Configuration and Management Overhead:** Relying on explicit, user-managed trust relationships demands careful configuration and may result in higher initial setup efforts. However, this overhead is justified by the resulting security and privacy benefits.
  - **Complexity in Policy Enforcement:** Integrating automated replication with strict access controls adds layers to the system’s complexity. These must be rigorously tested to maintain performance under various conditions.
  - **Testing Requirements:** Ensuring that trust and access control mechanisms behave as intended under simulated adverse conditions requires a robust deterministic simulation framework, increasing the scope of testing efforts.

## References to Requirements

- **Functional Requirements:**

  - FR-4: Peer-to-Peer Node Interaction – Trust management ensures that nodes only interact when explicitly authorized.
  - FR-5: Replication and Redundancy Management – Automated replication is restricted to user-approved nodes for data consistency.
  - FR-6: User Control and Access Management – Strong access control is vital for ensuring that all operations are transparent and auditable.

- **Non-Functional Requirements:**
  - NFR-1: Security & Privacy – Cryptographic access controls and explicit trust verification directly support our stringent security and privacy mandates.
  - NFR-2: Performance & Responsiveness – The design of these policies ensures that, even under simulated adverse conditions, the system maintains timely responses through efficient policy enforcement.
  - NFR-6: Deployability & Maintainability – The mechanisms are designed to be verifiable through deterministic simulations, aiding in predictable deployment and straightforward maintenance.

## Conclusion

Implementing stringent trust, access control, and replication policies ensures that our file storage system operates securely and transparently. By requiring explicit, user-approved node connections and enforcing robust cryptographic access controls, the system guarantees that replication occurs only among trusted nodes. This design not only meets our functional and non-functional requirements but also embodies our overarching mission of providing secure, user-controlled digital storage.