dsfx/docs/requirements/fr-6-user-control-and-access-management.md

# FR-6: User Control and Access Management

## 1. Overview

This document outlines the detailed requirements for ensuring that users retain complete control over their data through robust access management mechanisms. In FR-6, every user interaction—whether sharing files, granting or revoking access, or reviewing audit logs—must be transparent, auditable, and secure. The design requires that all access requests are cryptographically verified and logged in a tamper-evident manner. This functionality is critical for sustaining user trust, as it empowers individuals to manage who can access, modify, or share their information.

## 2. Objectives & Scope

### 2.1 Objectives

- **User Empowerment:**
  - Provide intuitive controls that allow users to manage permissions for file access and sharing.
  - Ensure that users maintain direct control over data access without relying on intermediaries.
- **Transparency and Auditability:**
  - Guarantee that all access-related operations are recorded in an immutable, auditable log.
  - Enable users to review historical access events and changes in permissions.
- **Secure Access Management:**
  - Employ strong cryptographic measures for authenticating access requests and validating user identity.
  - Ensure that operations such as grant, revoke, and modification of access rights are executed securely.
- **Multi-Device Coordination:**
  - Support consistency of access controls across devices in a multi-device environment by synchronizing audit logs and control data.

### 2.2 Scope

- Covers all interactions related to granting, modifying, or revoking access to file data and shared nodes.
- Applies to both local user interactions (via CLI or future web interfaces) and automated peer-to-peer replication processes.
- Includes integration with the audit logging system, ensuring that every access control change is verifiable.
- Interfaces with authentication, key management (ADR-0003), and secure communication modules (ADR-0007) to safely carry out access operations.

## 3. Detailed Requirements

### 3.1 Access Control Mechanisms

- **Cryptographic Credentials:**

  - All access requests (both granting and revoking rights) must be digitally signed using each user’s private key.
  - The system must verify these signatures on the server or node before processing permission changes.

- **Access Rights Definitions:**
  - Users shall be able to define granular access rights for different operations (read, write, share, delete) on individual files or groups of files.
  - Access rights definitions must be stored securely and associated with file metadata in the manifest.

### 3.2 User-Driven Permission Management

- **Granting Access:**

  - Users must be able to grant access to file data or specific file operations by explicitly specifying user identities or node credentials (public key-based).
  - The granting process should provide options for temporary or indefinite access, as needed.

- **Revoking Access:**

  - Users must have the ability to revoke access permissions at any time.
  - Revocation actions must immediately take effect and propagate to all nodes holding cached or replicated data.

- **Access Review and Audit:**
  - The interface should allow users to view a detailed list of all current access permissions for their files.
  - Audit logs must capture every grant, modification, or revocation event, including timestamps, user/node identifiers, and the nature of the access change.

### 3.3 Audit Logging and Transparency

- **Tamper-Evident Logs:**

  - All access control events must be recorded in an immutable, append-only log that is chained cryptographically (following the design from ADR-0006).
  - These logs should be integrated into the overall manifest, ensuring that any unauthorized changes will be immediately detectable.

- **Real-Time Notifications:**
  - The system should provide real-time feedback on critical access control events such as unexpected revocations or unauthorized access attempts.
  - Alerts should also be available in the UI for administrative review.

### 3.4 Interfacing with Multi-Device Synchronization

- **Consistent Access State:**

  - In a multi-device environment, access control changes should be synchronized across all active devices in near real-time.
  - Mechanisms such as manifest merging (ADR-0010) must be employed to ensure that permission changes are consistently reflected across each device.

- **Conflict Management:**
  - When multiple devices simultaneously update access permissions, the system must detect and resolve conflicts deterministically using logical timestamps.
  - Any ambiguities must be flagged for user review.

### 3.5 Error Handling and Recovery

- **Robustness in Adverse Conditions:**

  - The system should provide clear error messages and fallback procedures if an access control change fails (e.g., due to network issues or simulation-induced faults).
  - Automatic retry mechanisms must be integrated so that transient failures do not compromise overall security.

- **Verification on Recovery:**
  - After a reconnection or system recovery event, all access permissions must be revalidated to ensure consistency with the audit log.

## 4. Measurable Criteria & Test Cases

### 4.1 Automated End-to-End Tests

- **Access Permission Grant Test:**

  - Simulate a user granting read and write permissions to another user.
  - Verify via audit logs and manifest entries that the access grant is recorded accurately and that the delegated user can access the designated file operations accordingly.

- **Revocation Integrity Test:**

  - Execute user-driven revocation of access, then attempt access with the revoked credentials to ensure the operation is immediately blocked.
  - Check corresponding audit logs for the revocation event and ensure notifications were issued.

- **Synchronization Consistency Test:**
  - On multiple devices, change access permissions and confirm that all devices reflect the updated permissions within a predefined time window.
  - Validate that conflicting updates are resolved deterministically and logged appropriately.

### 4.2 Performance and Stress Testing

- **Response Time Measurement:**

  - Benchmark the time taken from initiating an access control change to the update propagating across the entire system.
  - Validate that response times meet target criteria under both normal and simulated adverse network conditions.

- **Audit Log Integrity Under Load:**
  - Stress-test the audit logging subsystem by generating a high volume of access control changes.
  - Ensure that logs remain tamper-evident and that retrieval and verification operations continue to perform within acceptable limits.

## 5. Dependencies & Integration Points

- **Key Management Module:**

  - This requirement collaborates closely with the key management strategy (ADR-0003) to ensure that cryptographic keys and digital signatures are managed securely.

- **Immutable Manifest and Audit Log:**

  - Integrates with the manifest system (ADR-0006) to provide a tamper-evident history of access control operations.

- **Communication Protocols:**

  - Secure messaging defined in ADR-0007 ensures that all access control messages are transmitted with confidentiality and integrity.

- **Multi-Device Synchronization Mechanisms:**
  - Leverages the versioning and manifest merging processes described in ADR-0010 to maintain consistent access rules across devices.

## 6. Security Considerations

- **Protection of Credentials:**

  - Ensure that private keys used for signing access control requests remain strictly on the client and are never transmitted over the network.

- **Prevention of Unauthorized Access:**

  - Implement robust authentication to prevent impersonation and unauthorized modifications of access rights.

- **Audit and Compliance:**

  - Strictly enforce audit logging to support compliance with policies or regulatory requirements regarding data access and user privacy.

- **Mitigation of Replay Attacks:**
  - Utilize nonce values or timestamps in access control messages to protect against replay attacks.

## 7. Conclusion

FR-6 establishes a comprehensive, secure, and user-centric model for managing access permissions and ensuring that all operations are fully transparent and auditable. By integrating strong cryptographic verification, tamper-evident logging, and consistent updates across multiple devices, this requirement not only empowers users with full control over their data but also reinforces the trustworthiness and integrity of the entire system—even under simulated adverse conditions.