v0.8.0b2

This release focuses on enhanced security, memory management, and code clarity for the Post-Quantum Feldman VSS library.

Major Highlights:

• Enhanced Memory Management: Implemented a MemoryMonitor class and integrated memory safety checks throughout the code to prevent excessive memory allocation and potential denial-of-service vulnerabilities. This drastically improves the library's robustness, especially when dealing with large threshold values and bit lengths.
• Improved Error Handling and Forensics: Enhanced exception handling throughout the codebase with more detailed forensic data included in exceptions for debugging/auditing purposes. Added get_forensic_data to errors for better debugging. Sanitized errors are used by default to prevent information leakage.
• Enhanced Security: Further hardened constant-time operations, Byzantine fault tolerance, and memory safety. Enhanced comments and documentation for security-sensitive areas of the code.

Detailed Changes:

• Core Security Enhancements:

  • constant_time_compare: Added input validation for gmpy2.mpz types.
  • secure_redundant_execution: Added a deterministically selected result to prevent timing side-channels, and added a more robust approach for gathering results in concurrent.futures.ThreadPoolExecutor.
  • _find_secure_pivot: Updated with constant-time update to minimum value and added more secure swaps. Added improved error check- ensure we're not returning a row with a zero pivot.
  • _compute_combined_randomizer Added type hints for function parameter.
  • _process_echo_consistency: Added input validation and more comprehensive Byzantine evidence collection.
  • _detect_byzantine_behavior: Added more explicit checks for malformed commitments and safer element access. Now explicitly requires passing the zero commitment check.
  • ``_generate_invalidity_evidence`: Added additional evidence about consistency checks.
  • secure_exp: Optimization: For safe primes p=2q+1, reduce modulo q instead of p-1. Check memory safety before proceeding.
  • create_polynomial_proof: Removed the use of id() for commitment keys and replaced it with the use of a secure cryptographic hashing algorithm to generate commitment keys, significantly improving the uniqueness and security of the keys.

• Memory Management:

  • MemoryMonitor Class: Added a MemoryMonitor class to track allocated memory and prevent exceeding limits.
  • check_allocation, allocate, release, get_usage_stats: Implemented methods for memory tracking and management.
  • check_memory_safety: Added comprehensive memory safety checks throughout the code.
  • estimate_mpz_size: Added a function to estimate memory usage of gmpy2.mpz numbers.
  • Integrated memory safety checks within CyclicGroup.exp, CyclicGroup.efficient_multi_exp, FeldmanVSS._evaluate_polynomial, and FeldmanVSS._secure_matrix_solve.

• Error Handling & Forensic Data:

  • Custom Exception Classes: Enhanced SecurityError, SerializationError, VerificationError, and ParameterError with fields like detailed_info, severity, timestamp, data_format, checksum_info, parameter_name, parameter_value, and expected_type for more comprehensive error reporting. Added get_forensic_data to errors for better debugging.
  • Detailed Error Messages: Added forensic data collection for debugging/auditing purposes.
  • Sanitized Errors: Sanitized errors are used by default to prevent information leakage.
  • Enhanced Input Validation: Added additional input validation and logging to various methods.
  • Corrected potential errors: Fixed a potential error that might occur if the input was undefined

• Code Quality & Clarity:

  • Type Hinting: Added type hints throughout the code for improved readability and maintainability.
  • Docstring Improvements: Enhanced docstrings for better clarity and consistency.
  • Removed Unnecessary Code: Removed code to free up memory in a class, as it is automatically handled by garbage collector.
  • Function Renaming: Renamed memory_safe_mpz_mul to check_memory_safety for more clarity.

• Bug Fixes:

  • Fixed an error with the input type of a function.

• Dependency Updates:

  • Updated requires-python version.
  • Updated dependencies version.

• Documentation:

  • Updated the documentation to accurately reflect the current codebase.
  • Enhanced docstrings throughout the code for better clarity and consistency.
  • Updated System Requirements section.
  • Added PyPi link.

Breaking Changes:

• Some exceptions now inherit from the custom classes (SecurityError, SerializationError, VerificationError, ParameterError) to provide additional diagnostic information. This should be backwards compatible in most cases, but code that specifically catches Exception may need to be updated.

Security Notes:

• This release addresses potential denial-of-service vulnerabilities related to excessive memory allocation.
• This release adds a deterministically selected result to prevent timing side-channels.
• This release adds a challenge consistency check to help detect malicious tampering.
• As a reminder, this library still has timing side-channel and fault injection vulnerabilities that cannot be adequately addressed in pure Python. These issues require implementation in a lower-level language like Rust to fix properly.

Upgrade Notes:

• It is highly recommended to upgrade to this version for improved security and stability.
• Pay special attention to the "Breaking Changes" section if your code relies on catching specific exception types.

Future Work:

• Further hardening of constant-time operations.
• More comprehensive testing and auditing.
• Fixing issues with Type Hints by creating custom stubs