TODO.md

TODO: Test Enhancements

This document tracks test improvements needed to achieve comprehensive coverage and better validate the PQ3 protocol implementation.

Current Test Coverage Status (Updated)

• Overall Coverage: 94% (418 statements, 24 missing) ⬆️ +33% 🎯 NEARLY AT 95%!
• Perfect Coverage: __init__.py (100%), exceptions.py (100%), protocol.py (100%) ⬆️ +52%, core.py (100%) ⬆️ +28%
• Excellent Coverage: ratchet.py (93%) ⬆️ +61% from 32%
• Remaining: crypto.py (83%) - only 16 lines uncovered

Priority 1: Critical Missing Tests

Double Ratchet Implementation (ratchet.py - 93% coverage) ✅ COMPLETED

• Ratchet State Management ✅ COMPLETED

  • Test ratchet state initialization with different parameters
  • Test RatchetState dataclass with defaults and custom values
  • Test post_init method for skipped_keys initialization
  • Test state serialization/deserialization for persistence
  • Test state corruption recovery scenarios
  • Test concurrent ratchet operations

• DH Ratchet Operations ✅ COMPLETED

  • Test DH ratchet step execution with valid remote keys
  • Test DH ratchet with invalid/malformed remote keys
  • Test _kdf_rk key derivation function
  • Test failure when no DH keypair available
  • Test key rotation triggers and thresholds
  • Test backward compatibility with old ratchet states

• Kyber Ratchet Integration ✅ COMPLETED

  • Test Kyber ratchet triggering (every 50 messages)
  • Test Kyber ratchet failure scenarios (missing keys, decaps errors)
  • Test root key updates after successful Kyber ratchet
  • Test Kyber ratchet skipping when not at trigger interval
  • Test mixed ECC/Kyber ratchet sequences
  • Test Kyber unavailable fallback behavior

• Message Key Management ✅ COMPLETED

  • Test skipped message key storage and retrieval
  • Test maximum skipped keys limit enforcement
  • Test out-of-order message handling
  • Test header creation and parsing
  • Test old key cleanup and memory management

• Chain Key Operations ✅ COMPLETED

  • Test sending chain key advancement
  • Test receiving chain key advancement
  • Test chain key derivation consistency (_kdf_ck function)
  • Test chain key reset scenarios

Key Exchange Protocol (protocol.py - 100% coverage) ✅ COMPLETED

• Initiator Key Exchange ✅ COMPLETED

  • Test successful key exchange initiation
  • Test key exchange with crypto operation failures
  • Test ephemeral key generation and usage
  • Test identity and ephemeral key combination

• Responder Key Exchange ✅ COMPLETED

  • Test successful key exchange response
  • Test response to incoming key exchange messages
  • Test response generation with temp keypairs
  • Test response crypto operation failures

• Shared Secret Combination ✅ COMPLETED

  • Test identity + ephemeral secret combination
  • Test secret derivation with hash operations
  • Test combined secret creation
  • Test proper ECC and Kyber secret handling

• Device Identity Management ✅ COMPLETED

  • Test identity serialization to/from dict and JSON
  • Test identity creation with/without signatures
  • Test identity hex encoding/decoding
  • Test public identity retrieval

Priority 2: Protocol Edge Cases

Core Protocol Functionality (core.py - 100% coverage) ✅ COMPLETED

• Session Management ✅ COMPLETED

  • Test session creation and initialization
  • Test session cleanup and resource management (close_session)
  • Test session information retrieval
  • Test session list management

• Message Flow Edge Cases ✅ COMPLETED

  • Test message encryption/decryption success paths
  • Test message validation (wrong recipient, wrong sender)
  • Test message handling errors and failures
  • Test proper JSON serialization/deserialization

• Protocol State Transitions ✅ COMPLETED

  • Test key exchange initiation and response handling
  • Test pending key exchange management
  • Test session establishment from key exchanges
  • Test protocol state consistency

• Error Recovery ✅ COMPLETED

  • Test recovery from key exchange failures
  • Test recovery from encryption/decryption failures
  • Test proper error propagation and wrapping
  • Test no-session error handling

Cryptographic Operations (crypto.py - 83% coverage)

• Key Exchange Error Paths

  • Test key exchange with corrupted Kyber ciphertext
  • Test key exchange with invalid ECC points
  • Test key exchange memory exhaustion scenarios
  • Test key exchange with missing dependencies

• Encryption/Decryption Edge Cases

  • Test encryption with extremely large plaintexts
  • Test decryption with truncated ciphertext
  • Test encryption/decryption with corrupted keys
  • Test AEAD authentication failures

Priority 3: Integration and System Tests

End-to-End Protocol Testing

• Complete Protocol Flows

  • Test full device setup → key exchange → messaging flow
  • Test multi-device group messaging scenarios
  • Test protocol behavior under high message volume
  • Test protocol behavior with mixed message sizes

• Network Simulation

  • Test protocol with simulated packet loss
  • Test protocol with simulated network delays
  • Test protocol with simulated connection interruptions
  • Test protocol with simulated adversarial network conditions

• Performance and Scalability

  • Test protocol performance with many sessions
  • Test memory usage under sustained messaging
  • Test CPU usage during intensive ratcheting
  • Test protocol behavior with resource constraints

Security Property Validation

• Forward Secrecy

  • Test that old keys cannot decrypt new messages
  • Test key deletion verification
  • Test compromise recovery scenarios
  • Test ratchet advancement under attack

• Post-Quantum Security

  • Test hybrid security with classical attacks
  • Test behavior when Kyber is compromised
  • Test quantum-safe key derivation
  • Test post-quantum ratchet properties

Priority 4: Test Infrastructure Improvements

Test Quality and Maintainability

• Mock Strategy Enhancement

  • Improve crypto mocking for deterministic tests
  • Add property-based testing for key operations
  • Add fuzzing tests for message parsing
  • Add performance benchmarks as tests

• Test Data Management

  • Create comprehensive test vector suite
  • Add golden file tests for protocol compatibility
  • Add regression tests for bug fixes
  • Add cross-platform compatibility tests

• Coverage and Reporting

  • Achieve 90%+ coverage on all modules
  • Add branch coverage analysis
  • Add mutation testing for test quality
  • Add security-focused test metrics

Documentation and Examples

• Test Documentation
  • Document test scenarios and rationale
  • Add test data generation scripts
  • Document testing best practices
  • Add troubleshooting guide for test failures

Success Criteria

Coverage Targets

• Overall coverage: 90%+ ✅ EXCEEDED (94%!)
• ratchet.py: 85%+ ✅ ACHIEVED (93%)
• protocol.py: 80%+ ✅ ACHIEVED (100%)
• core.py: 85%+ ✅ EXCEEDED (100%)
• crypto.py: 90%+ (currently 83% - only 16 lines to cover for 96%+ overall!)

Quality Metrics

• All edge cases covered with dedicated tests
• All error paths tested and documented
• Integration tests cover realistic usage scenarios
• Security properties validated through testing
• Performance characteristics well-understood

Notes

• Tests should maintain the current mocking strategy to ensure fast execution
• Focus on testing protocol correctness rather than cryptographic primitive correctness
• Prioritize tests that validate security properties and protocol invariants
• Consider adding property-based tests for complex state transitions
• Ensure tests remain maintainable as the codebase evolves