QRCLib implements post-quantum cryptographic algorithms that are designed to be secure against both classical and quantum computer attacks. This document outlines security considerations and best practices for using the library.

• Kyber: Lattice-based key encapsulation mechanism (KEM) that is secure against quantum computer attacks.
• Dilithium: Lattice-based digital signature scheme that provides quantum-resistant signatures.
• Both algorithms are NIST Post-Quantum Cryptography finalists.

1. Constant-Time Operations

   • All sensitive operations are implemented to run in constant time
   • Prevents timing attacks that could leak secret information
   • Uses constant-time comparison for signature verification

2. Secure Random Number Generation

   • Uses Python's secrets module for cryptographically secure randomness
   • Avoids using the standard random module which is not cryptographically secure
   • Implements proper seeding and entropy gathering

3. Memory Management

   • Sensitive data is overwritten when no longer needed
   • Avoids leaving secret keys in memory
   • Implements proper error handling to prevent information leaks

1. Key Generation

   • Generate new keys for each session/use case
   • Store private keys securely
   • Never reuse nonces or random values

2. Key Storage

   • Use secure key storage mechanisms
   • Encrypt private keys at rest
   • Implement proper access controls

3. Key Distribution

   • Use secure channels for key distribution
   • Verify key authenticity
   • Implement proper key rotation policies

1. Message Preparation

   • Hash messages before signing
   • Use constant-time operations
   • Validate input data

2. Signature Verification

   • Always verify signatures before trusting messages
   • Implement proper error handling
   • Use constant-time comparison

1. Secure Error Messages

   • Do not leak sensitive information in error messages
   • Use generic error messages for security-related failures
   • Implement proper logging without exposing secrets

2. Exception Handling

   • Catch and handle all exceptions properly
   • Do not expose internal state in exceptions
   • Maintain security invariants during error conditions

1. Code Review

   • Review security-critical code thoroughly
   • Follow secure coding guidelines
   • Use static analysis tools

2. Testing

   • Implement comprehensive test suites
   • Include security-focused test cases
   • Test error handling paths

3. Documentation

   • Document security assumptions
   • Provide clear security guidelines
   • Keep documentation up to date

1. Configuration

   • Use appropriate security parameters
   • Follow recommended key sizes
   • Implement proper key management

2. Integration

   • Use the library as intended
   • Do not modify security-critical code
   • Keep the library updated

3. Monitoring

   • Monitor for security issues
   • Implement proper logging
   • Have an incident response plan

1. Side-Channel Attacks

   • While we implement constant-time operations, the library may still be vulnerable to some side-channel attacks
   • Hardware-level attacks are not addressed
   • Cache timing attacks may still be possible

2. Implementation Constraints

   • Pure Python implementation may be slower than optimized C/C++ versions
   • Memory usage may be higher than optimal
   • Some operations may not be fully constant-time due to Python limitations

1. Version Control

   • All security fixes are documented
   • Security patches are clearly marked
   • Version numbers follow semantic versioning

2. Security Advisories

   • Security issues are published as advisories
   • CVEs are assigned when appropriate
   • Users are notified of security updates

3. Reporting Security Issues

   • Report security issues privately
   • Use responsible disclosure
   • Contact maintainers directly for security concerns

1. Standards

   • Follows NIST post-quantum cryptography standards
   • Implements FIPS-compliant random number generation
   • Adheres to cryptographic best practices

2. Auditing

   • Code is open for security audits
   • Changes are reviewed for security impact
   • Security issues are tracked and resolved

For security-related issues or concerns:

• Email: m@aiya.sh
• GitHub Security Advisories: https://github.com/BlockSavvy/QRCLib/security/advisories