dsfx/docs/requirements/nfr-1-security-and-privacy.md

# NFR-1: Security & Privacy

## 1. Overview

This document defines the non-functional requirements related to the security and privacy aspects of the self-hosted encrypted file storage system. The goal is to ensure that every component of the system—from client-side encryption to inter-node communication—is designed, implemented, and maintained with robust security measures. These measures must protect user data against unauthorized access, tampering, and breaches while maintaining user privacy, even in the face of simulated adverse conditions.

## 2. Objectives & Scope

### 2.1 Objectives

- **Data Confidentiality:**
  Ensure that no sensitive plaintext data is exposed during file upload, download, storage, or transmission.

- **Data Integrity:**
  Guarantee that data remains unaltered during transit and storage by using cryptographic checks (e.g., SHA-256) and authenticated encryption.

- **Strong Cryptographic Standards:**
  Enforce the use of industry-standard, authenticated encryption algorithms (e.g., AES-GCM or ChaCha20-Poly1305) and robust key derivation functions (e.g., Argon2, scrypt, or PBKDF2).

- **Secure Communication:**
  Ensure all network communications (client-to-server, inter-node) are secured with protocols like TLS or equivalent secure channels that are resistant to man-in-the-middle (MitM) attacks.

- **Privacy by Design:**
  Architect the system so that sensitive operations, including encryption, decryption, and key management, occur entirely on the client side, minimizing exposure of sensitive data.

### 2.2 Scope

- Applies to all components and interactions within the system including file operations, node communication, audit logging, and user access controls.
- Covers cryptographic operations, secure transport layers, and the handling and storage of keys.
- Includes integration with deterministic simulation testing to ensure security measures remain effective even under simulated network and system failure conditions.

## 3. Detailed Requirements

### 3.1 Strong Cryptographic Practices

- **Encryption Algorithms:**

  - The system must utilize authenticated encryption algorithms (e.g., AES-GCM or ChaCha20-Poly1305) to ensure both confidentiality and integrity.
  - Algorithms must be chosen based on hardware capabilities (e.g., AES-NI for AES-GCM) and fallback to alternatives when necessary.

- **Key Derivation and Management:**
  - Keys must be derived using strong key derivation functions (e.g., Argon2, scrypt, or PBKDF2) on the client side.
  - Private encryption keys shall be generated and stored securely on the client, never transmitted or replicated externally.
  - Integration with OS-level keychains or HSMs should be supported for environments that offer hardware-backed key management.

### 3.2 Secure Communication Protocols

- **Transport Layer Security:**

  - All communications (client-server and inter-node) must use secure transport protocols such as TLS.
  - Certificates and mutual authentication should be enforced to prevent unauthorized access and MitM attacks.

- **Custom Protocol Security:**
  - For inter-node communication through custom binary protocols, built-in encryption and integrity checks (e.g., message authentication codes) must be provided, ensuring those protocols meet equivalent security standards to TLS.

### 3.3 Data Integrity and Verification

- **Cryptographic Hashes:**

  - File data, including subdivided file chunks, must be associated with cryptographic hashes (e.g., SHA-256) that are used to verify data integrity during storage and transmission.
  - Integrity checks must be performed before and after encryption/decryption to ensure that no data corruption or tampering has occurred.

- **Auditability:**
  - Security events, including encryption operations and communication handshakes, must be logged in a tamper-evident format.
  - Logs should be maintained in an append-only manner with cryptographic chaining to support auditability and forensic analysis.

### 3.4 Privacy Preservation

- **Client-Side Security:**

  - Critical operations such as encryption, decryption, and key derivation must occur exclusively on the client side.
  - Sensitive data (e.g., plaintext files, encryption keys) must not leave the client environment.

- **Minimal Exposure:**
  - Only ciphertext should be transmitted or stored; any metadata transmitted must be carefully chosen to avoid leaking sensitive information.

### 3.5 Integration with Deterministic Simulation

- **Simulation of Adverse Conditions:**
  - The security measures must be verified under deterministic simulation to test for vulnerabilities and operational integrity under scenarios like network intercepts, simulated tampering, or system faults.
  - The simulation framework should be used to validate that secure communications remain intact and that cryptographic operations are consistently performed without exposing sensitive data.

## 4. Measurable Criteria & Test Cases

### 4.1 Security Testing

- **Penetration Testing:**

  - Conduct penetration tests to confirm that no critical vulnerabilities (e.g., exposure of plaintext data, weak ciphers) are present.
  - Tests should simulate various attack vectors including MitM attacks, replay attacks, and side-channel attacks.

- **Cryptographic Validation:**
  - Automated tests must verify that encryption and decryption functions produce correct and consistent results (i.e., round-trip tests) and that decryption fails when data integrity is compromised.
  - Performance metrics for key derivation should be measured to ensure adequate protection against brute-force attacks.

### 4.2 Communication & Network Security Tests

- **TLS and Protocol Testing:**
  - Validate that all endpoints enforce TLS, and that communications cannot be downgraded to insecure channels.
  - Use controlled environments to capture network traffic and confirm that no plaintext data is transmitted.

### 4.3 Integration with Simulation

- **Simulated Attack Scenarios:**
  - Utilize the deterministic simulation framework to simulate network attacks (e.g., packet tampering, replay) and confirm that security mechanisms correctly detect and mitigate such events.
  - Test the system’s ability to maintain integrity and confidentiality under induced adversarial conditions.

## 5. Dependencies & Integration Points

- **Key Management Module:**

  - Relies on secure key management strategies (described in ADR-0003) to ensure that encryption keys are generated, stored, and utilized exclusively on the client side.

- **Communication Protocols:**

  - Built upon secure protocols as defined in ADR-0007 and the custom security measures listed therein.

- **Audit and Manifest Systems:**

  - Works in conjunction with the immutable manifest (ADR-0006) to guarantee that all security events are logged and traceable.

- **Deterministic Simulation Framework:**
  - Integration with the simulation framework is critical to validating security functionalities under controlled test conditions.

## 6. Security Considerations

- **Resilience Against Breaches:**

  - The system should be designed to minimize damage in case of a breach, ensuring that attackers cannot easily derive keys or intercept sensitive operations.

- **Monitoring and Response:**

  - Real-time monitoring should detect abnormal activities (e.g., unusual authentication failures) and alert administrators or trigger automated countermeasures.

- **Compliance and Best Practices:**
  - The implementation must comply with industry-standard security practices and regulatory requirements where applicable.
  - Regular security audits and updates must be scheduled to address emerging threats and vulnerabilities.

## 7. Conclusion

NFR-1 establishes the comprehensive security and privacy framework essential for a trustworthy encrypted file storage system. By enforcing strong cryptographic practices, ensuring secure communications, maintaining data integrity, and integrating rigorous testing and simulation, the system is designed to protect user data throughout its lifecycle. These measures form the foundation for user trust and the overall resilience of the system.
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											2025-03-21 16:42:01 -04:00
+								# NFR-1: Security & Privacy
 								## 1. Overview
 								This document defines the non-functional requirements related to the security and privacy aspects of the self-hosted encrypted file storage system. The goal is to ensure that every component of the system—from client-side encryption to inter-node communication—is designed, implemented, and maintained with robust security measures. These measures must protect user data against unauthorized access, tampering, and breaches while maintaining user privacy, even in the face of simulated adverse conditions.
 								## 2. Objectives & Scope
 								### 2.1 Objectives
 								- **Data Confidentiality:**
 								  Ensure that no sensitive plaintext data is exposed during file upload, download, storage, or transmission.
 								- **Data Integrity:**
 								  Guarantee that data remains unaltered during transit and storage by using cryptographic checks (e.g., SHA-256) and authenticated encryption.
 								- **Strong Cryptographic Standards:**
 								  Enforce the use of industry-standard, authenticated encryption algorithms (e.g., AES-GCM or ChaCha20-Poly1305) and robust key derivation functions (e.g., Argon2, scrypt, or PBKDF2).
 								- **Secure Communication:**
 								  Ensure all network communications (client-to-server, inter-node) are secured with protocols like TLS or equivalent secure channels that are resistant to man-in-the-middle (MitM) attacks.
 								- **Privacy by Design:**
 								  Architect the system so that sensitive operations, including encryption, decryption, and key management, occur entirely on the client side, minimizing exposure of sensitive data.
 								### 2.2 Scope
 								- Applies to all components and interactions within the system including file operations, node communication, audit logging, and user access controls.
 								- Covers cryptographic operations, secure transport layers, and the handling and storage of keys.
 								- Includes integration with deterministic simulation testing to ensure security measures remain effective even under simulated network and system failure conditions.
 								## 3. Detailed Requirements
 								### 3.1 Strong Cryptographic Practices
 								- **Encryption Algorithms:**
 								  - The system must utilize authenticated encryption algorithms (e.g., AES-GCM or ChaCha20-Poly1305) to ensure both confidentiality and integrity.
 								  - Algorithms must be chosen based on hardware capabilities (e.g., AES-NI for AES-GCM) and fallback to alternatives when necessary.
 								- **Key Derivation and Management:**
 								  - Keys must be derived using strong key derivation functions (e.g., Argon2, scrypt, or PBKDF2) on the client side.
 								  - Private encryption keys shall be generated and stored securely on the client, never transmitted or replicated externally.
 								  - Integration with OS-level keychains or HSMs should be supported for environments that offer hardware-backed key management.
 								### 3.2 Secure Communication Protocols
 								- **Transport Layer Security:**
 								  - All communications (client-server and inter-node) must use secure transport protocols such as TLS.
 								  - Certificates and mutual authentication should be enforced to prevent unauthorized access and MitM attacks.
 								- **Custom Protocol Security:**
 								  - For inter-node communication through custom binary protocols, built-in encryption and integrity checks (e.g., message authentication codes) must be provided, ensuring those protocols meet equivalent security standards to TLS.
 								### 3.3 Data Integrity and Verification
 								- **Cryptographic Hashes:**
 								  - File data, including subdivided file chunks, must be associated with cryptographic hashes (e.g., SHA-256) that are used to verify data integrity during storage and transmission.
 								  - Integrity checks must be performed before and after encryption/decryption to ensure that no data corruption or tampering has occurred.
 								- **Auditability:**
 								  - Security events, including encryption operations and communication handshakes, must be logged in a tamper-evident format.
 								  - Logs should be maintained in an append-only manner with cryptographic chaining to support auditability and forensic analysis.
 								### 3.4 Privacy Preservation
 								- **Client-Side Security:**
 								  - Critical operations such as encryption, decryption, and key derivation must occur exclusively on the client side.
 								  - Sensitive data (e.g., plaintext files, encryption keys) must not leave the client environment.
 								- **Minimal Exposure:**
 								  - Only ciphertext should be transmitted or stored; any metadata transmitted must be carefully chosen to avoid leaking sensitive information.
 								### 3.5 Integration with Deterministic Simulation
 								- **Simulation of Adverse Conditions:**
 								  - The security measures must be verified under deterministic simulation to test for vulnerabilities and operational integrity under scenarios like network intercepts, simulated tampering, or system faults.
 								  - The simulation framework should be used to validate that secure communications remain intact and that cryptographic operations are consistently performed without exposing sensitive data.
 								## 4. Measurable Criteria & Test Cases
 								### 4.1 Security Testing
 								- **Penetration Testing:**
 								  - Conduct penetration tests to confirm that no critical vulnerabilities (e.g., exposure of plaintext data, weak ciphers) are present.
 								  - Tests should simulate various attack vectors including MitM attacks, replay attacks, and side-channel attacks.
 								- **Cryptographic Validation:**
 								  - Automated tests must verify that encryption and decryption functions produce correct and consistent results (i.e., round-trip tests) and that decryption fails when data integrity is compromised.
 								  - Performance metrics for key derivation should be measured to ensure adequate protection against brute-force attacks.
 								### 4.2 Communication & Network Security Tests
 								- **TLS and Protocol Testing:**
 								  - Validate that all endpoints enforce TLS, and that communications cannot be downgraded to insecure channels.
 								  - Use controlled environments to capture network traffic and confirm that no plaintext data is transmitted.
 								### 4.3 Integration with Simulation
 								- **Simulated Attack Scenarios:**
 								  - Utilize the deterministic simulation framework to simulate network attacks (e.g., packet tampering, replay) and confirm that security mechanisms correctly detect and mitigate such events.
 								  - Test the system’s ability to maintain integrity and confidentiality under induced adversarial conditions.
 								## 5. Dependencies & Integration Points
 								- **Key Management Module:**
 								  - Relies on secure key management strategies (described in ADR-0003) to ensure that encryption keys are generated, stored, and utilized exclusively on the client side.
 								- **Communication Protocols:**
 								  - Built upon secure protocols as defined in ADR-0007 and the custom security measures listed therein.
 								- **Audit and Manifest Systems:**
 								  - Works in conjunction with the immutable manifest (ADR-0006) to guarantee that all security events are logged and traceable.
 								- **Deterministic Simulation Framework:**
 								  - Integration with the simulation framework is critical to validating security functionalities under controlled test conditions.
 								## 6. Security Considerations
 								- **Resilience Against Breaches:**
 								  - The system should be designed to minimize damage in case of a breach, ensuring that attackers cannot easily derive keys or intercept sensitive operations.
 								- **Monitoring and Response:**
 								  - Real-time monitoring should detect abnormal activities (e.g., unusual authentication failures) and alert administrators or trigger automated countermeasures.
 								- **Compliance and Best Practices:**
 								  - The implementation must comply with industry-standard security practices and regulatory requirements where applicable.
 								  - Regular security audits and updates must be scheduled to address emerging threats and vulnerabilities.
 								## 7. Conclusion
 								NFR-1 establishes the comprehensive security and privacy framework essential for a trustworthy encrypted file storage system. By enforcing strong cryptographic practices, ensuring secure communications, maintaining data integrity, and integrating rigorous testing and simulation, the system is designed to protect user data throughout its lifecycle. These measures form the foundation for user trust and the overall resilience of the system.