# Security and Trust Steering Document

**Version**: 1.0  
**Last Updated**: 2025-01-16  
**Status**: Active  

## Executive Summary

This document establishes the security principles, trust models, and cryptographic standards for Saorsa Core. Security is foundational to P2P networks, where traditional perimeter defenses don't apply and trust must be established through cryptographic means and reputation systems.

## Security Philosophy

### Zero Trust Architecture

**Principle**: Never trust, always verify.

**Implementation**:
- All network communications are authenticated and encrypted
- Every operation includes cryptographic proof of authorization
- Node reputation is continuously evaluated and updated
- No implicit trust relationships exist

**Rationale**: P2P networks operate in hostile environments where any participant could be malicious. Traditional network security models based on perimeter defense are ineffective.

### Defense in Depth

**Principle**: Multiple independent security layers provide resilience against various attack vectors.

**Layers**:
1. **Cryptographic Layer**: Encryption, signatures, proof-of-work
2. **Network Layer**: Rate limiting, connection management, traffic analysis
3. **Reputation Layer**: EigenTrust, Byzantine detection, peer scoring
4. **Application Layer**: Access controls, audit logging, anomaly detection

### Proactive Security

**Principle**: Anticipate and mitigate threats before they manifest.

**Implementation**:
- Post-quantum cryptography for future-proofing
- Continuous security monitoring and threat detection
- Regular security audits and penetration testing
- Automated vulnerability scanning and patching

## Cryptographic Standards

### Current Cryptographic Primitives

#### Digital Signatures
- **Algorithm**: ML-DSA (post-quantum)
- **Security Level**: 128-bit equivalent
- **Performance**: ~70,000 signatures/second, ~25,000 verifications/second
- **Key Size**: 32-byte public keys, 64-byte signatures
- **Rationale**: Excellent performance, resistance to timing attacks, deterministic signatures

#### Key Exchange
- **Algorithm**: ML-KEM (post-quantum key encapsulation)
- **Security Level**: 128-bit equivalent
- **Performance**: ~100,000 operations/second
- **Key Size**: 32-byte keys
- **Rationale**: Fast key agreement with perfect forward secrecy

#### Symmetric Encryption
- **Algorithm**: ChaCha20-Poly1305
- **Security Level**: 256-bit key strength
- **Performance**: ~1 GB/sec encryption throughput
- **Rationale**: Constant-time implementation, strong authentication

#### Hashing
- **Algorithm**: BLAKE3
- **Security Level**: 256-bit output (configurable)
- **Performance**: ~3 GB/sec on modern CPUs
- **Features**: Parallelizable, tree hashing, incremental updates
- **Rationale**: Faster than SHA-2, suitable for Merkle trees

#### Key Derivation
- **Algorithm**: HKDF with BLAKE3
- **Purpose**: Derive multiple keys from master secret
- **Security**: Information-theoretic security with proper entropy
- **Use Cases**: Session keys, encryption keys, authentication tokens

### Post-Quantum Cryptography

#### Digital Signatures (Future)
- **Algorithm**: ML-DSA (Dilithium)
- **Security Level**: NIST Level 3 (equivalent to AES-192)
- **Implementation**: Behind feature flag for gradual deployment
- **Migration Strategy**: Hybrid signatures during transition period

#### Key Exchange (Future)
- **Algorithm**: ML-KEM (Kyber)
- **Security Level**: NIST Level 3
- **Implementation**: PQC-only via saorsa-pqc and ant-quic
- **Timeline**: Deployment by 2027 based on quantum computer development

### Cryptographic Key Management

#### Key Generation
- **Entropy Source**: Hardware random number generator (HRNG) when available
- **Fallback**: ChaCha20-based CSPRNG seeded from OS entropy
- **Key Derivation**: HKDF for deriving child keys from master keys
- **Storage**: Encrypted with user-derived keys, never stored in plaintext

#### Key Rotation
- **Schedule**: Automatic rotation every 30 days for session keys
- **Trigger**: Manual rotation on compromise detection
- **Process**: Gradual rollout with backward compatibility period
- **Verification**: Cryptographic proof of rotation authority

#### Key Escrow
- **Policy**: No key escrow for user data encryption
- **Exception**: Network infrastructure keys may have secure backup
- **Implementation**: Threshold secret sharing for infrastructure keys
- **Access Control**: Multi-party authorization required for key recovery

## Trust and Reputation System

### EigenTrust Algorithm

#### Core Concept
EigenTrust computes global trust values based on local trust relationships, using the principal eigenvector of the trust matrix.

#### Mathematical Foundation
```
Trust Matrix: T[i,j] = normalized local trust from node i to node j
Global Trust: t = (cT^T + (1-c)p)t
Where c = damping factor (0.85), p = pre-trust vector
```

#### Implementation Details
- **Local Trust Computation**: Based on successful/failed interactions
- **Trust Aggregation**: Weighted by reputation of recommending nodes
- **Convergence**: Power iteration method with early stopping
- **Performance**: O(n log n) computation for sparse trust graphs

#### Security Properties
- **Sybil Resistance**: Requires trusted pre-trust relationships
- **Byzantine Tolerance**: Robust against malicious recommendations
- **Transitivity**: Trust propagates through network relationships
- **Adaptability**: Updates based on observed behavior

### Placement System Integration

#### Trust-Based Node Selection
The placement system integrates EigenTrust scores using the weighted formula:
```
w_i = (τ_i^α) * (p_i^β) * (c_i^γ) * d_i
```
Where:
- `τ_i`: EigenTrust reputation score (0.0-1.0)
- `α`: Trust weight exponent (typically 0.4)
- Higher trust scores exponentially increase selection probability

#### Byzantine Fault Tolerance
- **Model**: f-out-of-3f+1 Byzantine tolerance
- **Detection**: Continuous audit system identifies Byzantine behavior
- **Response**: Automatic reputation penalties and placement exclusion
- **Recovery**: Gradual reputation rehabilitation for reformed nodes

#### Trust Feedback Loop
1. **Placement**: Select nodes based on trust scores
2. **Monitoring**: Continuous audit of storage and retrieval performance
3. **Evaluation**: Measure node reliability and responsiveness
4. **Update**: Adjust trust scores based on observed behavior
5. **Propagation**: Share trust updates with network peers

### Reputation Metrics

#### Performance Metrics
- **Availability**: Percentage of successful connection attempts
- **Latency**: Average response time for requests
- **Bandwidth**: Sustained throughput for data transfers
- **Reliability**: Consistency of performance over time

#### Security Metrics
- **Authentication**: Rate of valid cryptographic signatures
- **Integrity**: Frequency of data corruption detection
- **Compliance**: Adherence to protocol specifications
- **Cooperation**: Participation in network maintenance tasks

#### Behavioral Metrics
- **Uptime**: Duration of continuous network participation
- **Churn**: Frequency of connection/disconnection cycles
- **Resource Sharing**: Contribution to network storage and bandwidth
- **Protocol Updates**: Adoption of new protocol versions

## Threat Model and Mitigations

### Network-Level Threats

#### Sybil Attacks
**Threat**: Adversary creates multiple fake identities to gain influence.
**Mitigation**: 
- EigenTrust requires pre-trusted relationships
- Proof-of-work for identity creation
- Geographic diversity requirements
- Resource-based admission control

#### Eclipse Attacks
**Threat**: Adversary isolates victim from honest network.
**Mitigation**:
- Diverse peer selection algorithms
- Geographic diversity in connections
- Reputation-based peer prioritization
- Out-of-band peer discovery mechanisms

#### Distributed Denial of Service (DDoS)
**Threat**: Coordinated attack overwhelms network resources.
**Mitigation**:
- Rate limiting per peer and globally
- Proof-of-work for expensive operations
- Connection limits with prioritization
- Automatic blacklisting of attack sources

#### Traffic Analysis
**Threat**: Passive adversary analyzes communication patterns.
**Mitigation**:
- Onion routing for sensitive communications
- Traffic padding to obscure patterns
- Random delays and batching
- Cover traffic generation

### Data-Level Threats

#### Data Tampering
**Threat**: Malicious nodes modify stored data.
**Mitigation**:
- Cryptographic hashes for integrity verification
- Digital signatures for authenticity
- Byzantine-fault-tolerant storage
- Continuous audit and verification

#### Data Availability Attacks
**Threat**: Adversary prevents access to stored data.
**Mitigation**:
- Redundant storage across multiple nodes
- Geographic distribution of replicas
- Automated repair and re-replication
- Incentive mechanisms for storage provision

#### Privacy Breaches
**Threat**: Unauthorized access to private data.
**Mitigation**:
- End-to-end encryption for all user data
- Zero-knowledge proofs for privacy-preserving operations
- Secure multi-party computation for analytics
- Data minimization principles

### Cryptographic Threats

#### Quantum Computing
**Threat**: Large-scale quantum computers break current cryptography.
**Timeline**: Estimated 10-20 years for cryptographically relevant quantum computers.
**Mitigation**:
- Post-quantum cryptography implementation
- Hybrid classical/post-quantum schemes during transition
- Continuous monitoring of quantum computing progress
- Rapid deployment capability for new algorithms

#### Cryptographic Vulnerabilities
**Threat**: Discovery of weaknesses in cryptographic algorithms.
**Mitigation**:
- Diverse cryptographic primitives to avoid single points of failure
- Regular security audits and cryptographic reviews
- Automatic update mechanisms for critical security patches
- Fallback algorithms for emergency situations

#### Side-Channel Attacks
**Threat**: Information leakage through timing, power, or electromagnetic emissions.
**Mitigation**:
- Constant-time cryptographic implementations
- Hardware security modules (HSMs) for key operations
- Randomization and blinding techniques
- Regular side-channel analysis and testing

## Security Incident Response

### Incident Classification

#### Critical (P0)
- Cryptographic key compromise
- Network-wide denial of service
- Mass data breach or corruption
- **Response Time**: <1 hour
- **Team**: Full security team activation

#### High (P1)
- Individual node compromise
- Protocol vulnerability exploitation
- Significant reputation system manipulation
- **Response Time**: <4 hours
- **Team**: Security team lead + specialists

#### Medium (P2)
- Performance degradation attacks
- Minor protocol violations
- Suspicious activity patterns
- **Response Time**: <24 hours
- **Team**: Security team rotation

#### Low (P3)
- Configuration issues
- Documentation security gaps
- Monitoring alert tuning
- **Response Time**: <72 hours
- **Team**: Individual security engineer

### Response Procedures

#### Detection and Analysis
1. **Automated Detection**: Security monitoring systems identify anomalies
2. **Manual Reporting**: Community members report suspicious activity
3. **Impact Assessment**: Evaluate scope and severity of incident
4. **Evidence Collection**: Preserve logs and forensic evidence

#### Containment and Mitigation
1. **Immediate Containment**: Isolate affected systems
2. **Damage Assessment**: Determine extent of compromise
3. **Temporary Mitigations**: Deploy emergency fixes
4. **Communication**: Notify affected parties and community

#### Recovery and Lessons Learned
1. **Root Cause Analysis**: Determine how incident occurred
2. **Permanent Fixes**: Implement comprehensive solutions
3. **Process Improvements**: Update procedures and monitoring
4. **Post-Incident Review**: Document lessons learned and improvements

## Security Monitoring and Auditing

### Continuous Monitoring

#### Network Monitoring
- **Connection Patterns**: Detect unusual peer relationships
- **Traffic Analysis**: Identify anomalous communication patterns
- **Performance Metrics**: Monitor for degradation attacks
- **Protocol Compliance**: Verify adherence to specifications

#### Cryptographic Monitoring
- **Key Usage**: Track key rotation and expiration
- **Signature Verification**: Monitor signature validation rates
- **Entropy Quality**: Assess random number generation quality
- **Algorithm Performance**: Benchmark cryptographic operations

#### Reputation Monitoring
- **Trust Score Changes**: Track rapid reputation fluctuations
- **Behavior Patterns**: Identify coordinated malicious activity
- **Network Topology**: Monitor for centralization attacks
- **Economic Metrics**: Track resource usage and incentives

### Audit Procedures

#### Regular Security Audits
- **Frequency**: Quarterly comprehensive audits
- **Scope**: Code review, architecture assessment, penetration testing
- **External Audits**: Annual third-party security assessments
- **Bug Bounty**: Continuous community-driven vulnerability discovery

#### Compliance Auditing
- **Privacy Regulations**: GDPR, CCPA compliance verification
- **Cryptographic Standards**: FIPS 140-2, Common Criteria evaluation
- **Industry Standards**: ISO 27001, SOC 2 compliance
- **Open Source**: License compliance and supply chain security

#### Incident Post-Mortems
- **Timeline Reconstruction**: Detailed incident timeline
- **Contributing Factors**: Analysis of root causes
- **Effectiveness Review**: Evaluate response procedures
- **Improvement Recommendations**: Concrete action items

## Security Best Practices

### Development Practices

#### Secure Coding Standards
- **Input Validation**: Validate and sanitize all external inputs
- **Error Handling**: Fail securely with minimal information disclosure
- **Memory Safety**: Use Rust's ownership system to prevent memory vulnerabilities
- **Dependency Management**: Regular updates and vulnerability scanning

#### Code Review Process
- **Security Focus**: All changes reviewed for security implications
- **Cryptographic Review**: Specialized review for cryptographic code
- **Threat Modeling**: Consider attack vectors for new features
- **Testing Requirements**: Security test cases for all functionality

#### Deployment Security
- **Build Security**: Reproducible builds with signed artifacts
- **Infrastructure Security**: Hardened deployment environments
- **Secrets Management**: Secure handling of cryptographic keys
- **Update Mechanisms**: Secure and verifiable software updates

### Operational Practices

#### Access Control
- **Principle of Least Privilege**: Minimum necessary permissions
- **Multi-Factor Authentication**: Strong authentication for critical systems
- **Regular Access Reviews**: Periodic permission audits
- **Separation of Duties**: No single person controls critical operations

#### Backup and Recovery
- **Encrypted Backups**: All backups encrypted with strong cryptography
- **Offline Storage**: Critical backups stored offline for ransomware protection
- **Recovery Testing**: Regular disaster recovery exercises
- **Business Continuity**: Comprehensive continuity planning

#### Communication Security
- **Secure Channels**: Encrypted communication for all sensitive discussions
- **Information Classification**: Clear data classification and handling procedures
- **Incident Communication**: Secure channels for incident response
- **Public Communication**: Responsible disclosure for security issues

## Future Security Considerations

### Emerging Threats

#### AI-Powered Attacks
- **Threat**: Machine learning used to optimize attacks
- **Timeline**: Already emerging in sophisticated attacks
- **Mitigation**: AI-powered defense systems, behavioral analysis

#### Supply Chain Attacks
- **Threat**: Compromise of development tools and dependencies
- **Timeline**: Increasing frequency and sophistication
- **Mitigation**: Dependency verification, build security, code signing

#### Quantum Computing Progress
- **Threat**: Earlier than expected quantum computer development
- **Timeline**: Potentially accelerated by breakthrough discoveries
- **Mitigation**: Accelerated post-quantum cryptography deployment

### Research and Development

#### Privacy-Preserving Technologies
- **Zero-Knowledge Proofs**: Scalable privacy-preserving verification
- **Secure Multi-Party Computation**: Collaborative computation without data disclosure
- **Homomorphic Encryption**: Computation on encrypted data
- **Differential Privacy**: Statistical privacy guarantees

#### Advanced Cryptography
- **Threshold Cryptography**: Distributed cryptographic operations
- **Identity-Based Encryption**: Simplified key management
- **Attribute-Based Encryption**: Fine-grained access control
- **Verifiable Random Functions**: Cryptographically provable randomness

#### Network Security Innovations
- **Mesh Networking**: Resilient peer-to-peer topologies
- **Software-Defined Perimeters**: Dynamic security boundaries
- **Behavioral Analytics**: AI-powered anomaly detection
- **Quantum Key Distribution**: Ultimate communication security

## Conclusion

Security in P2P networks requires a fundamentally different approach than traditional centralized systems. By implementing defense in depth, maintaining cryptographic agility, and fostering a security-conscious culture, Saorsa Core can provide robust security in the face of evolving threats.

The integration of EigenTrust reputation management with the placement system provides a novel approach to Byzantine fault tolerance that scales with network size while maintaining strong security properties. Continuous monitoring, regular audits, and proactive threat mitigation ensure the network remains secure as it grows and evolves.

## References

- [EigenTrust: Reputation Management in P2P Networks](https://nlp.stanford.edu/pubs/eigentrust.pdf)
- [NIST Post-Quantum Cryptography Standardization](https://csrc.nist.gov/projects/post-quantum-cryptography)
- [The Byzantine Generals Problem](https://lamport.azurewebsites.net/pubs/byz.pdf)
- [Practical Byzantine Fault Tolerance](http://pmg.csail.mit.edu/papers/osdi99.pdf)
- [Zero Trust Architecture](https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-207.pdf)
- [Cryptographic Agility and Interoperability](https://tools.ietf.org/html/rfc7696)
