# BZZZ Security Model

**Version 2.0 - Phase 2B Edition**  
Comprehensive security architecture and threat analysis for BZZZ's unified semantic context publishing platform.

## Table of Contents

1. [Security Overview](#security-overview)
2. [Threat Model](#threat-model)
3. [Cryptographic Design](#cryptographic-design)
4. [Role-Based Access Control](#role-based-access-control)
5. [Key Management](#key-management)
6. [Network Security](#network-security)
7. [Data Protection](#data-protection)
8. [Consensus Security](#consensus-security)
9. [Audit & Compliance](#audit--compliance)
10. [Security Operations](#security-operations)

## Security Overview

BZZZ Phase 2B implements a comprehensive security model designed to protect semantic context data in a distributed environment while maintaining usability and performance. The security architecture is built on proven cryptographic primitives and follows defense-in-depth principles.

### Security Objectives

1. **Confidentiality**: Only authorized roles can access specific content
2. **Integrity**: Content cannot be modified without detection
3. **Availability**: System remains operational despite node failures
4. **Authentication**: Verify identity of all system participants
5. **Authorization**: Enforce role-based access permissions
6. **Non-repudiation**: Actions are attributable to specific agents
7. **Forward Secrecy**: Compromise of keys doesn't affect past communications
8. **Consensus Security**: Admin elections are tamper-resistant

### Security Principles

- **Zero Trust**: No implicit trust between system components
- **Least Privilege**: Minimal necessary permissions for each role
- **Defense in Depth**: Multiple security layers and controls
- **Cryptographic Agility**: Ability to upgrade cryptographic algorithms
- **Transparent Security**: Security operations are observable and auditable
- **Distributed Security**: No single points of failure in security model

**Cross-References**:
- Implementation: `pkg/crypto/` and `pkg/election/` packages
- Architecture: [ARCHITECTURE.md](ARCHITECTURE.md#security-architecture)
- Configuration: [CONFIG_REFERENCE.md](CONFIG_REFERENCE.md#security-configuration)

## Threat Model

### Attack Surface Analysis

#### 1. Network-Based Attacks

**P2P Network Communication**:
```
Threats:
├── Man-in-the-Middle (MITM) attacks on P2P connections
├── Traffic analysis and metadata leakage
├── DHT poisoning and routing attacks
├── Eclipse attacks isolating nodes
├── DDoS attacks on bootstrap nodes
└── Eavesdropping on unencrypted channels

Mitigations:
├── Noise protocol for transport encryption
├── Peer identity verification via libp2p
├── Multiple bootstrap peers for redundancy
├── Rate limiting and connection management
├── Content-level encryption (independent of transport)
└── Peer reputation and blacklisting
```

**DHT-Specific Attacks**:
```
Threats:
├── Sybil attacks creating fake nodes
├── Content poisoning with malicious data
├── Selective routing attacks
├── Storage amplification attacks
└── Routing table poisoning

Mitigations:
├── Peer ID verification and validation
├── Content integrity via SHA256 hashes
├── Multiple content replicas across nodes
├── Rate limiting on storage operations
└── Merkle tree validation for large content
```

#### 2. Cryptographic Attacks

**Age Encryption Attacks**:
```
Threats:
├── Key compromise leading to content decryption
├── Weak random number generation
├── Side-channel attacks on encryption operations
├── Quantum computing threats to X25519
└── Algorithm implementation vulnerabilities

Mitigations:
├── Regular key rotation procedures
├── Secure random number generation (crypto/rand)
├── Constant-time implementations
├── Post-quantum migration planning
└── Cryptographic library audits and updates
```

**Shamir Secret Sharing Attacks**:
```
Threats:
├── Share collection attacks during elections
├── Insider attacks by node operators
├── Threshold attacks with colluding nodes
├── Share reconstruction timing attacks
└── Mathematical attacks on finite fields

Mitigations:
├── Secure share distribution protocols
├── Node authentication and authorization
├── Consensus validation of share reconstruction
├── Constant-time reconstruction algorithms
└── Large prime field (257-bit) for security
```

#### 3. System-Level Attacks

**Election System Attacks**:
```
Threats:
├── Election manipulation and vote buying
├── Split brain scenarios with multiple admins
├── Admin impersonation attacks
├── Consensus failure leading to DoS
└── Long-range attacks on election history

Mitigations:
├── Cryptographic vote verification
├── Split brain detection algorithms
├── Strong admin authentication requirements
├── Consensus timeout and recovery mechanisms
└── Election audit logs and validation
```

**Role-Based Access Attacks**:
```
Threats:
├── Privilege escalation attacks
├── Role impersonation
├── Authority bypass attempts
├── Configuration tampering
└── Social engineering attacks

Mitigations:
├── Strict role validation and enforcement
├── Cryptographic role binding
├── Immutable configuration signing
├── Multi-party authorization for role changes
└── Security awareness and training
```

### Adversary Model

#### Internal Adversaries (Malicious Nodes)

**Capabilities**:
- Full access to one or more BZZZ nodes
- Knowledge of system protocols and implementation
- Ability to modify local node behavior
- Access to local keys and configuration
- Network connectivity to other nodes

**Limitations**:
- Cannot break cryptographic primitives
- Cannot compromise more than minority of nodes simultaneously
- Cannot forge digital signatures without private keys
- Subject to network-level monitoring and detection

#### External Adversaries (Network Attackers)

**Capabilities**:
- Monitor network traffic between nodes
- Inject, modify, or block network messages
- Launch DoS attacks against individual nodes
- Attempt cryptanalysis of observed ciphertext
- Social engineering attacks against operators

**Limitations**:
- Cannot access node-internal state or keys
- Cannot break Age encryption or Shamir secret sharing
- Limited by network topology and routing
- Subject to rate limiting and access controls

#### Quantum Adversaries (Future Threat)

**Capabilities**:
- Break X25519 elliptic curve cryptography
- Break symmetric encryption with Grover's algorithm
- Compromise all current Age-encrypted content
- Threaten current consensus security mechanisms

**Mitigations**:
- Post-quantum cryptography migration planning
- Hybrid classical/quantum-resistant schemes
- Forward secrecy to limit exposure window
- Cryptographic agility for algorithm upgrades

**Cross-References**:
- Threat mitigation code: `pkg/crypto/age_crypto.go`, `pkg/election/election.go`
- Network security: [ARCHITECTURE.md](ARCHITECTURE.md#network-architecture)
- Monitoring: [MONITORING.md](MONITORING.md#security-monitoring)

## Cryptographic Design

### Age Encryption Implementation

#### Core Cryptographic Components

**X25519 Key Exchange**:
```
Algorithm: Curve25519 Elliptic Curve Diffie-Hellman
Key Size: 256 bits (32 bytes)
Security Level: ~128 bits (equivalent to AES-128)
Quantum Resistance: Vulnerable (Shor's algorithm)

Public Key Format: age1{52-char-base32}
Private Key Format: AGE-SECRET-KEY-1{64-char-base64}

Example:
Public:  age1abcdef1234567890abcdef1234567890abcdef1234567890ab
Private: AGE-SECRET-KEY-1ABCDEF1234567890ABCDEF1234567890ABCDEF1234567890ABCDEF1234567890
```

**ChaCha20-Poly1305 Encryption**:
```
Algorithm: ChaCha20 stream cipher + Poly1305 MAC
Key Size: 256 bits derived from X25519 exchange
Nonce: 96 bits (12 bytes) randomly generated
MAC: 128 bits (16 bytes) for authentication
Security Level: ~256 bits symmetric security

Benefits:
├── Constant-time implementation (side-channel resistant)
├── High performance on modern CPUs
├── Patent-free and widely audited
└── Quantum-resistant against Grover's algorithm (256→128 bits)
```

#### Multi-Recipient Encryption

**Algorithm Overview**:
```go
func EncryptForMultipleRoles(content []byte, roles []string) ([]byte, error) {
    // 1. Generate ephemeral key pair
    ephemeralPrivate, ephemeralPublic := GenerateX25519KeyPair()
    
    // 2. For each recipient role:
    recipients := make([]age.Recipient, 0, len(roles))
    for _, role := range roles {
        // Get role's public key
        roleKey := GetRolePublicKey(role)
        recipients = append(recipients, roleKey)
    }
    
    // 3. Age encrypt with multiple recipients
    return age.Encrypt(content, recipients...)
}
```

**Security Properties**:
- Each recipient can independently decrypt content
- Adding/removing recipients requires re-encryption
- No key sharing between recipients
- Forward secrecy: ephemeral keys not stored

#### Cryptographic Key Derivation

**Role Key Generation**:
```go
func GenerateRoleKeys() (*AgeKeyPair, error) {
    // Use cryptographically secure random number generator
    identity, err := age.GenerateX25519Identity()
    if err != nil {
        return nil, err
    }
    
    return &AgeKeyPair{
        PublicKey:  identity.Recipient().String(),
        PrivateKey: identity.String(),
    }, nil
}
```

**Key Validation**:
```go
func ValidateAgeKey(key string, isPrivate bool) error {
    if isPrivate {
        // Validate private key format and parse
        if !strings.HasPrefix(key, "AGE-SECRET-KEY-1") {
            return ErrInvalidPrivateKeyFormat
        }
        _, err := age.ParseX25519Identity(key)
        return err
    } else {
        // Validate public key format and parse
        if !strings.HasPrefix(key, "age1") {
            return ErrInvalidPublicKeyFormat  
        }
        _, err := age.ParseX25519Recipient(key)
        return err
    }
}
```

### Shamir Secret Sharing Design

#### Mathematical Foundation

**Finite Field Arithmetic**:
```
Field: GF(p) where p is 257-bit prime
Prime: 208351617316091241234326746312124448251235562226470491514186331217050270460481

Polynomial Construction:
f(x) = s + a₁x + a₂x² + ... + aₜ₋₁xᵗ⁻¹ (mod p)

Where:
- s = secret (admin private key)
- aᵢ = random coefficients
- t = threshold (3 for 3-of-5 scheme)
```

**Share Generation**:
```go
func (sss *ShamirSecretSharing) SplitSecret(secret string) ([]Share, error) {
    secretInt := new(big.Int).SetBytes([]byte(secret))
    prime := getPrime257()
    
    // Generate random polynomial coefficients
    coefficients := make([]*big.Int, sss.threshold)
    coefficients[0] = secretInt // Constant term is the secret
    
    for i := 1; i < sss.threshold; i++ {
        coeff, err := rand.Int(rand.Reader, prime)
        if err != nil {
            return nil, err
        }
        coefficients[i] = coeff
    }
    
    // Evaluate polynomial at different points
    shares := make([]Share, sss.totalShares)
    for i := 0; i < sss.totalShares; i++ {
        x := big.NewInt(int64(i + 1))
        y := evaluatePolynomial(coefficients, x, prime)
        shares[i] = Share{Index: i + 1, Value: encodeShare(x, y)}
    }
    
    return shares, nil
}
```

**Secret Reconstruction (Lagrange Interpolation)**:
```go
func lagrangeInterpolation(points []Point, targetX, prime *big.Int) *big.Int {
    result := big.NewInt(0)
    
    for i := 0; i < len(points); i++ {
        // Calculate Lagrange basis polynomial Lᵢ(targetX)
        numerator := big.NewInt(1)
        denominator := big.NewInt(1)
        
        for j := 0; j < len(points); j++ {
            if i != j {
                // numerator *= (targetX - points[j].X)
                temp := new(big.Int).Sub(targetX, points[j].X)
                numerator.Mul(numerator, temp)
                numerator.Mod(numerator, prime)
                
                // denominator *= (points[i].X - points[j].X)
                temp = new(big.Int).Sub(points[i].X, points[j].X)
                denominator.Mul(denominator, temp) 
                denominator.Mod(denominator, prime)
            }
        }
        
        // Calculate modular inverse and Lagrange term
        denominatorInv := modularInverse(denominator, prime)
        lagrangeBasis := new(big.Int).Mul(numerator, denominatorInv)
        lagrangeBasis.Mod(lagrangeBasis, prime)
        
        // Add yᵢ * Lᵢ(targetX) to result
        term := new(big.Int).Mul(points[i].Y, lagrangeBasis)
        result.Add(result, term)
        result.Mod(result, prime)
    }
    
    return result
}
```

#### Security Analysis

**Threshold Security**:
- Any t-1 shares provide no information about secret
- Information-theoretic security (unconditionally secure)
- Reconstruction requires exactly t shares minimum
- Additional shares improve fault tolerance

**Attack Resistance**:
```
Share Compromise: Up to t-1 shares can be compromised safely
Interpolation Attacks: Prevented by large finite field (257-bit prime)
Timing Attacks: Constant-time reconstruction implementation
Side Channel: Secure memory handling and zeroization
```

**Cross-References**:
- Cryptographic implementation: `pkg/crypto/age_crypto.go`, `pkg/crypto/shamir.go`
- Key management: Section [Key Management](#key-management)
- Test vectors: `pkg/crypto/age_crypto_test.go`, `pkg/crypto/shamir_test.go`

## Role-Based Access Control

### Authority Hierarchy

#### Access Control Matrix

```
┌─────────────────────────────────────────────────────────────────┐
│                   Role-Based Access Matrix                      │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│               Content Creator Role                              │
│            ┌────────┬──────────┬───────────┬──────────┐         │
│ Accessor   │ admin  │architect │developer  │observer  │         │
│ Role    ┌──┼────────┼──────────┼───────────┼──────────┤         │
│ admin   │  │   ✅   │    ✅    │     ✅    │    ✅    │         │
│ archit. │  │   ❌   │    ✅    │     ✅    │    ✅    │         │
│ dev.    │  │   ❌   │    ❌    │     ✅    │    ✅    │         │
│ obs.    │  │   ❌   │    ❌    │     ❌    │    ✅    │         │
│         └──┴────────┴──────────┴───────────┴──────────┘         │
│                                                                 │
│ Legend: ✅ Can decrypt, ❌ Cannot decrypt                        │
└─────────────────────────────────────────────────────────────────┘
```

#### Authority Level Definitions

**Master Authority (`admin`)**:
```yaml
authority_level: master
capabilities:
  - decrypt_all_content      # Can decrypt content from any role
  - admin_elections         # Can participate in admin elections
  - key_reconstruction      # Can reconstruct admin keys from shares
  - slurp_functionality     # SLURP context curation capabilities
  - system_administration   # Full system control
  - consensus_participation # Vote in all consensus operations

security_implications:
  - Highest privilege level in system
  - Can access all historical and current decisions
  - Critical for system recovery and maintenance
  - Must be distributed across multiple nodes (3-of-5 threshold)
```

**Decision Authority (`senior_software_architect`)**:
```yaml  
authority_level: decision
capabilities:
  - strategic_decisions     # Make high-level architectural decisions
  - decrypt_subordinate     # Decrypt content from lower authority levels
  - escalation_authority    # Escalate issues to admin level
  - cross_project_access    # Access decisions across multiple projects
  - team_coordination       # Coordinate across multiple development teams

security_implications:
  - Can access strategic and implementation level content
  - Cannot access admin-only system information
  - Trusted with sensitive architectural information
  - Can influence system direction through decisions
```

**Suggestion Authority (`backend_developer`, `frontend_developer`)**:
```yaml
authority_level: suggestion  
capabilities:
  - implementation_decisions # Make tactical implementation decisions
  - decrypt_own_content     # Decrypt own and subordinate content
  - project_specific_access # Access content within assigned projects
  - task_execution         # Execute assigned development tasks
  - peer_collaboration     # Collaborate with same-level peers

security_implications:
  - Limited to implementation-level information
  - Cannot access strategic architectural decisions
  - Project-scoped access reduces blast radius
  - Peer-level collaboration maintains team effectiveness
```

**Read-Only Authority (`observer`)**:
```yaml
authority_level: read_only
capabilities:
  - monitoring_access       # Access monitoring and status information
  - decrypt_observer_only   # Only decrypt content created by observers
  - system_health_viewing   # View system health and performance metrics
  - audit_log_access       # Read audit logs (observer-level only)

security_implications:  
  - Minimal security risk if compromised
  - Cannot access sensitive implementation details
  - Useful for external monitoring and compliance
  - No impact on system security if credentials leaked
```

### Access Validation Implementation

```go
// Role-based decryption validation
func (ac *AgeCrypto) CanDecryptContent(targetRole string) (bool, error) {
    currentRole := ac.config.Agent.Role
    if currentRole == "" {
        return false, fmt.Errorf("no role configured")
    }
    
    // Get current role definition
    roles := config.GetPredefinedRoles()
    current, exists := roles[currentRole]
    if !exists {
        return false, fmt.Errorf("role '%s' not found", currentRole)
    }
    
    // Check if current role can decrypt target role content
    for _, decryptableRole := range current.CanDecrypt {
        if decryptableRole == targetRole || decryptableRole == "*" {
            return true, nil
        }
    }
    
    return false, nil
}

// Authority level comparison  
func (cfg *Config) GetRoleAuthority(roleName string) (AuthorityLevel, error) {
    roles := GetPredefinedRoles()
    role, exists := roles[roleName]
    if !exists {
        return "", fmt.Errorf("role '%s' not found", roleName)
    }
    
    return role.AuthorityLevel, nil
}

// Hierarchical permission checking
func (cfg *Config) CanDecryptRole(targetRole string) (bool, error) {
    currentAuthority, err := cfg.GetRoleAuthority(cfg.Agent.Role)
    if err != nil {
        return false, err
    }
    
    targetAuthority, err := cfg.GetRoleAuthority(targetRole)  
    if err != nil {
        return false, err
    }
    
    // Master can decrypt everything
    if currentAuthority == AuthorityMaster {
        return true, nil
    }
    
    // Decision can decrypt decision, suggestion, read_only
    if currentAuthority == AuthorityDecision {
        return targetAuthority != AuthorityMaster, nil
    }
    
    // Suggestion can decrypt suggestion, read_only  
    if currentAuthority == AuthoritySuggestion {
        return targetAuthority == AuthoritySuggestion || 
               targetAuthority == AuthorityReadOnly, nil
    }
    
    // Read-only can only decrypt read-only
    return currentAuthority == targetAuthority, nil
}
```

### Role Configuration Security

**Immutable Role Definitions**:
```yaml
# Configuration signing for role integrity
role_configuration:
  signature: "sha256:abcdef1234..."  # SHA256 signature of role config
  signed_by: "admin"                # Must be signed by admin role
  timestamp: "2025-01-08T15:30:00Z"  # Signing timestamp  
  version: 2                        # Configuration version

roles:
  backend_developer:
    authority_level: suggestion
    can_decrypt: [backend_developer]
    model: "ollama/codegemma"
    age_keys:
      public_key: "age1..."
      private_key_ref: "encrypted_ref_to_secure_storage"
```

**Role Binding Cryptographic Verification**:
```go
func VerifyRoleBinding(agentID string, role string, signature []byte) error {
    // Construct role binding message
    message := fmt.Sprintf("agent:%s:role:%s:timestamp:%d", 
        agentID, role, time.Now().Unix())
    
    // Verify signature with admin public key
    adminKey := GetAdminPublicKey()
    valid := ed25519.Verify(adminKey, []byte(message), signature)
    if !valid {
        return fmt.Errorf("invalid role binding signature")
    }
    
    return nil
}
```

**Cross-References**:
- Role implementation: `pkg/config/roles.go`
- Access control validation: `pkg/crypto/age_crypto.go:CanDecryptContent()`
- Configuration security: [CONFIG_REFERENCE.md](CONFIG_REFERENCE.md#security-configuration)

## Key Management

### Key Lifecycle Management

#### Key Generation

**Role Key Generation**:
```go
func GenerateRoleKeyPair(roleName string) (*AgeKeyPair, error) {
    // Generate cryptographically secure key pair
    keyPair, err := GenerateAgeKeyPair()
    if err != nil {
        return nil, fmt.Errorf("failed to generate keys for role %s: %w", 
            roleName, err)
    }
    
    // Validate key format and functionality  
    if err := ValidateAgeKey(keyPair.PublicKey, false); err != nil {
        return nil, fmt.Errorf("generated public key invalid: %w", err)
    }
    
    if err := ValidateAgeKey(keyPair.PrivateKey, true); err != nil {
        return nil, fmt.Errorf("generated private key invalid: %w", err)
    }
    
    // Test encryption/decryption functionality
    testContent := []byte("key_validation_test_content")
    encrypted, err := testEncryptWithKey(testContent, keyPair.PublicKey)
    if err != nil {
        return nil, fmt.Errorf("key encryption test failed: %w", err)
    }
    
    decrypted, err := testDecryptWithKey(encrypted, keyPair.PrivateKey)
    if err != nil {
        return nil, fmt.Errorf("key decryption test failed: %w", err)
    }
    
    if !bytes.Equal(testContent, decrypted) {
        return nil, fmt.Errorf("key functionality test failed")
    }
    
    return keyPair, nil
}
```

**Admin Key Distribution**:
```go
func DistributeAdminKey(adminPrivateKey string, nodeIDs []string) error {
    // Create Shamir secret sharing instance (3-of-5)
    sss, err := NewShamirSecretSharing(3, 5)
    if err != nil {
        return fmt.Errorf("failed to create Shamir instance: %w", err)
    }
    
    // Split admin key into shares
    shares, err := sss.SplitSecret(adminPrivateKey)
    if err != nil {
        return fmt.Errorf("failed to split admin key: %w", err)
    }
    
    // Distribute shares to nodes via secure channels
    for i, nodeID := range nodeIDs {
        if i >= len(shares) {
            break
        }
        
        err := securelyDistributeShare(nodeID, shares[i])
        if err != nil {
            return fmt.Errorf("failed to distribute share to node %s: %w", 
                nodeID, err)
        }
    }
    
    // Verify reconstruction is possible
    testShares := shares[:3] // Use minimum threshold
    reconstructed, err := sss.ReconstructSecret(testShares)
    if err != nil {
        return fmt.Errorf("admin key reconstruction test failed: %w", err)
    }
    
    if reconstructed != adminPrivateKey {
        return fmt.Errorf("reconstructed admin key doesn't match original")
    }
    
    return nil
}
```

#### Key Rotation

**Regular Key Rotation Process**:
```yaml
key_rotation:
  schedule: quarterly                    # Every 3 months
  trigger_events:
    - security_incident                  # Immediate rotation on breach
    - employee_departure                 # Role-specific rotation
    - algorithm_vulnerability            # Cryptographic weakness discovery
    - compliance_requirement             # Regulatory requirements

rotation_process:
  1. generate_new_keys                   # Generate new key pairs
  2. update_configuration                # Update role configurations
  3. re_encrypt_content                  # Re-encrypt recent content with new keys
  4. distribute_new_keys                 # Secure distribution to authorized nodes
  5. validate_functionality              # Test new keys work correctly
  6. deprecate_old_keys                  # Mark old keys as deprecated
  7. monitor_usage                       # Monitor for old key usage
  8. revoke_old_keys                     # Permanently revoke after grace period
```

**Key Rotation Implementation**:
```go
func RotateRoleKeys(roleName string, gracePeriod time.Duration) error {
    // 1. Generate new key pair
    newKeyPair, err := GenerateRoleKeyPair(roleName)
    if err != nil {
        return fmt.Errorf("failed to generate new keys: %w", err)
    }
    
    // 2. Get current keys
    oldKeyPair := GetCurrentRoleKeys(roleName)
    
    // 3. Update configuration with new keys (keep old keys during grace period)
    err = UpdateRoleKeysWithGracePeriod(roleName, newKeyPair, oldKeyPair, gracePeriod)
    if err != nil {
        return fmt.Errorf("failed to update role keys: %w", err)
    }
    
    // 4. Re-encrypt recent content with new keys
    err = ReEncryptRecentContent(roleName, newKeyPair, time.Now().Add(-30*24*time.Hour))
    if err != nil {
        return fmt.Errorf("failed to re-encrypt content: %w", err)
    }
    
    // 5. Schedule old key revocation
    ScheduleKeyRevocation(roleName, oldKeyPair, gracePeriod)
    
    // 6. Audit log the rotation
    LogSecurityEvent(SecurityEventKeyRotation, map[string]interface{}{
        "role": roleName,
        "old_key_fingerprint": HashPublicKey(oldKeyPair.PublicKey),
        "new_key_fingerprint": HashPublicKey(newKeyPair.PublicKey),
        "grace_period": gracePeriod,
        "timestamp": time.Now(),
    })
    
    return nil
}
```

#### Key Storage Security

**Secure Key Storage**:
```yaml
key_storage:
  method: encrypted_at_rest              # Keys encrypted when stored
  encryption: AES-256-GCM               # Storage encryption algorithm
  key_derivation: PBKDF2                # Key derivation for storage passwords
  iterations: 100000                    # PBKDF2 iteration count
  file_permissions: 0600                # Restrictive file permissions
  directory_permissions: 0700           # Secure directory permissions
  backup_encryption: true               # Encrypt key backups
  secure_delete: true                   # Securely delete old keys

access_controls:
  user: bzzz                           # Dedicated user account
  group: bzzz                          # Dedicated group
  sudoers: false                       # No sudo access required
  selinux: enforcing                   # SELinux mandatory access control
  apparmor: complain                   # AppArmor additional confinement
```

**Key Storage Implementation**:
```go
func SecurelyStorePrivateKey(roleName, privateKey, password string) error {
    // 1. Derive storage key from password
    salt := make([]byte, 32)
    if _, err := rand.Read(salt); err != nil {
        return fmt.Errorf("failed to generate salt: %w", err)
    }
    
    storageKey := pbkdf2.Key([]byte(password), salt, 100000, 32, sha256.New)
    
    // 2. Encrypt private key with AES-256-GCM
    block, err := aes.NewCipher(storageKey)
    if err != nil {
        return fmt.Errorf("failed to create cipher: %w", err)
    }
    
    gcm, err := cipher.NewGCM(block)
    if err != nil {
        return fmt.Errorf("failed to create GCM: %w", err)
    }
    
    nonce := make([]byte, gcm.NonceSize())
    if _, err := rand.Read(nonce); err != nil {
        return fmt.Errorf("failed to generate nonce: %w", err)
    }
    
    encryptedKey := gcm.Seal(nil, nonce, []byte(privateKey), nil)
    
    // 3. Construct storage structure
    keyStorage := EncryptedKeyStorage{
        Salt:         salt,
        Nonce:        nonce,
        EncryptedKey: encryptedKey,
        Algorithm:    "AES-256-GCM",
        KDF:          "PBKDF2",
        Iterations:   100000,
        Timestamp:    time.Now(),
    }
    
    // 4. Save to secure file location
    keyPath := filepath.Join(getSecureKeyDirectory(), fmt.Sprintf("%s.key", roleName))
    return saveEncryptedKey(keyPath, keyStorage)
}
```

### Hardware Security Module (HSM) Integration

**HSM Configuration**:
```yaml
hsm_integration:
  enabled: true                        # Enable HSM usage
  provider: "pkcs11"                   # PKCS#11 interface
  library_path: "/usr/lib/libpkcs11.so" # HSM library location
  slot_id: 0                           # HSM slot identifier
  pin_file: "/etc/bzzz/hsm_pin"        # HSM PIN file (secure)
  
  key_generation:
    admin_keys: true                   # Generate admin keys in HSM
    role_keys: false                   # Generate role keys locally (performance)
    
  operations:
    signing: true                      # Use HSM for signing operations
    key_derivation: true               # Use HSM for key derivation
    random_generation: true            # Use HSM RNG for entropy
```

**Cross-References**:
- Key management implementation: `pkg/crypto/` package
- Configuration security: [CONFIG_REFERENCE.md](CONFIG_REFERENCE.md#key-management)
- HSM integration: `pkg/crypto/hsm.go` (future implementation)

## Network Security

### Transport Layer Security

#### libp2p Security Stack

**Security Transport Protocols**:
```yaml
libp2p_security:
  transport_protocols:
    - noise:                           # Primary transport security
        version: "Noise_XX_25519_ChaChaPoly_SHA256"
        features:
          - forward_secrecy: true
          - mutual_authentication: true
          - resistance_to_replay: true
          - post_compromise_security: true
    
    - tls:                            # Alternative transport security
        version: "1.3"
        cipher_suites:
          - "TLS_CHACHA20_POLY1305_SHA256"
          - "TLS_AES_256_GCM_SHA384"
        
  peer_authentication:
    method: "cryptographic_identity"   # Ed25519 peer IDs
    key_size: 256                     # 256-bit Ed25519 keys
    signature_validation: true        # Verify peer signatures
    
  connection_security:
    max_connections_per_peer: 10      # Limit connections per peer
    connection_timeout: 30s           # Connection establishment timeout
    handshake_timeout: 10s           # Security handshake timeout
    rate_limiting: true              # Rate limit connection attempts
```

#### Network-Level Protections

**DDoS Protection**:
```go
type ConnectionManager struct {
    maxConnections     int
    connectionsPerPeer map[peer.ID]int
    rateLimiter       *rate.Limiter
    blacklist         map[peer.ID]time.Time
    mutex             sync.RWMutex
}

func (cm *ConnectionManager) AllowConnection(peerID peer.ID) bool {
    cm.mutex.RLock()
    defer cm.mutex.RUnlock()
    
    // Check blacklist
    if banTime, exists := cm.blacklist[peerID]; exists {
        if time.Now().Before(banTime) {
            return false // Still banned
        }
        delete(cm.blacklist, peerID) // Ban expired
    }
    
    // Check rate limiting
    if !cm.rateLimiter.Allow() {
        cm.banPeer(peerID, 5*time.Minute) // Temporary ban
        return false
    }
    
    // Check connection limits
    if cm.connectionsPerPeer[peerID] >= cm.maxConnections {
        return false
    }
    
    return true
}

func (cm *ConnectionManager) banPeer(peerID peer.ID, duration time.Duration) {
    cm.blacklist[peerID] = time.Now().Add(duration)
    cm.logSecurityEvent("peer_banned", peerID, duration)
}
```

**Traffic Analysis Resistance**:
```yaml
traffic_protection:
  message_padding:
    enabled: true                     # Add random padding to messages
    min_size: 512                    # Minimum message size
    max_size: 4096                   # Maximum message size
    random_delay: true               # Add random delays
    
  decoy_traffic:
    enabled: false                   # Disable by default (performance)
    frequency: "10s"                 # Decoy message frequency
    size_variation: true             # Vary decoy message sizes
    
  connection_mixing:
    enabled: true                    # Mix connections across peers
    pool_size: 20                    # Connection pool size
    rotation_interval: "5m"          # Rotate connections every 5 minutes
```

### P2P Network Hardening

#### Peer Discovery Security

**mDNS Security**:
```yaml
mdns_security:
  service_name: "bzzz-peer-discovery" # Service identifier
  ttl: 300                           # Time-to-live for announcements
  rate_limiting: true                # Rate limit discovery messages
  authentication: true               # Authenticate discovery responses
  
  security_measures:
    - validate_peer_ids              # Cryptographically validate peer IDs
    - check_service_fingerprint      # Verify service fingerprints
    - rate_limit_responses           # Limit response frequency
    - blacklist_malicious_peers      # Blacklist misbehaving peers
```

**Bootstrap Peer Security**:
```yaml
bootstrap_security:
  peer_validation:
    cryptographic_verification: true  # Verify peer ID signatures
    reputation_tracking: true        # Track peer reputation scores
    health_monitoring: true          # Monitor bootstrap peer health
    
  failover_configuration:
    min_bootstrap_peers: 2           # Minimum working bootstrap peers
    max_bootstrap_peers: 10          # Maximum bootstrap peer connections
    health_check_interval: "30s"    # Health check frequency
    failover_timeout: "10s"          # Failover decision timeout
    
  bootstrap_peer_requirements:
    uptime_requirement: "99%"        # Minimum uptime requirement
    version_compatibility: "2.0+"   # Minimum BZZZ version required
    security_compliance: true       # Must meet security standards
```

#### DHT Security Measures

**Sybil Attack Protection**:
```go
type SybilProtection struct {
    peerReputation    map[peer.ID]*PeerReputation
    identityVerifier  *IdentityVerifier
    rateLimiter      *TokenBucket
    minimumAge       time.Duration
}

type PeerReputation struct {
    PeerID         peer.ID
    FirstSeen      time.Time
    SuccessfulOps  int64
    FailedOps      int64
    ReputationScore float64
    IsVerified     bool
}

func (sp *SybilProtection) ValidatePeer(peerID peer.ID) error {
    rep, exists := sp.peerReputation[peerID]
    if !exists {
        // New peer - add with low initial reputation
        sp.peerReputation[peerID] = &PeerReputation{
            PeerID:         peerID,
            FirstSeen:      time.Now(),
            SuccessfulOps:  0,
            FailedOps:      0,
            ReputationScore: 0.1, // Low initial reputation
            IsVerified:     false,
        }
        return nil
    }
    
    // Check minimum age requirement
    if time.Since(rep.FirstSeen) < sp.minimumAge {
        return fmt.Errorf("peer too new: %s", peerID)
    }
    
    // Check reputation score
    if rep.ReputationScore < 0.5 {
        return fmt.Errorf("peer reputation too low: %f", rep.ReputationScore)
    }
    
    return nil
}
```

**Content Integrity Verification**:
```go
func VerifyDHTContent(content []byte, metadata *UCXLMetadata) error {
    // 1. Verify content hash matches metadata
    hash := sha256.Sum256(content)
    expectedHash := metadata.Hash
    if fmt.Sprintf("%x", hash) != expectedHash {
        return fmt.Errorf("content hash mismatch")
    }
    
    // 2. Verify content size matches metadata  
    if len(content) != metadata.Size {
        return fmt.Errorf("content size mismatch")
    }
    
    // 3. Verify content is properly encrypted
    if !isValidAgeEncryption(content) {
        return fmt.Errorf("invalid Age encryption format")
    }
    
    // 4. Verify metadata signature (if present)
    if metadata.Signature != "" {
        err := verifyMetadataSignature(metadata)
        if err != nil {
            return fmt.Errorf("invalid metadata signature: %w", err)
        }
    }
    
    return nil
}
```

**Cross-References**:
- Network security implementation: `p2p/` and `pubsub/` packages
- DHT security: `pkg/dht/encrypted_storage.go`
- Connection management: `p2p/node.go`

## Data Protection

### Content Encryption

#### Encryption-at-Rest

**Local Storage Encryption**:
```yaml
storage_encryption:
  cache_encryption:
    algorithm: "AES-256-GCM"           # Symmetric encryption for cache
    key_derivation: "PBKDF2"          # Key derivation for cache keys
    iterations: 100000                # PBKDF2 iterations
    iv_generation: "random"           # Random IV per encrypted item
    
  configuration_encryption:
    method: "age_encryption"          # Age encryption for configuration
    recipient: "admin_key"            # Encrypt with admin public key
    backup_encryption: true          # Encrypt configuration backups
    
  log_encryption:
    audit_logs: true                 # Encrypt sensitive audit logs
    security_events: true            # Encrypt security event logs  
    key_operations: true             # Encrypt key operation logs
```

**DHT Storage Protection**:
```yaml
dht_protection:
  content_encryption:
    mandatory: true                  # All content must be encrypted
    algorithm: "Age"                 # Age encryption standard
    key_management: "role_based"     # Role-based key management
    integrity_checking: true        # SHA256 integrity verification
    
  metadata_protection:
    sensitive_metadata: true         # Protect sensitive metadata fields
    anonymization: true              # Anonymize where possible
    access_logging: true             # Log all metadata access
    
  replication_security:
    encrypted_replication: true      # Replicas remain encrypted
    integrity_across_peers: true    # Verify integrity across peers
    secure_peer_selection: true     # Select trustworthy peers for replicas
```

#### Data Classification

**Content Classification Levels**:
```yaml
classification_levels:
  public:
    description: "Information intended for public consumption"
    encryption_required: false
    access_control: none
    examples: ["system_announcements", "public_documentation"]
    
  internal:
    description: "Information for internal team use"
    encryption_required: true
    access_control: role_based
    examples: ["task_completions", "code_reviews"]
    
  confidential:
    description: "Sensitive business or technical information"
    encryption_required: true
    access_control: strict_role_based
    examples: ["architectural_decisions", "security_configurations"]
    
  restricted:
    description: "Highly sensitive information requiring special protection"
    encryption_required: true
    access_control: admin_only
    examples: ["admin_keys", "security_incidents", "audit_logs"]
```

**Automated Data Classification**:
```go
func ClassifyDecisionContent(decision *TaskDecision) ClassificationLevel {
    // Classify based on content type
    switch decision.Context["decision_type"] {
    case "security", "admin", "incident":
        return ClassificationRestricted
    case "architecture", "strategic":
        return ClassificationConfidential  
    case "code", "implementation":
        return ClassificationInternal
    case "announcement", "status":
        return ClassificationPublic
    default:
        return ClassificationInternal // Safe default
    }
}

func ApplyDataProtection(content []byte, level ClassificationLevel) ([]byte, error) {
    switch level {
    case ClassificationPublic:
        return content, nil // No encryption required
        
    case ClassificationInternal:
        return encryptForRole(content, getCurrentRole())
        
    case ClassificationConfidential:
        roles := getDecisionMakingRoles()
        return encryptForMultipleRoles(content, roles)
        
    case ClassificationRestricted:
        return encryptForRole(content, "admin")
        
    default:
        return nil, fmt.Errorf("unknown classification level: %v", level)
    }
}
```

### Privacy Protection

#### Data Minimization

**Metadata Minimization**:
```go
type MinimalMetadata struct {
    // Required fields only
    ContentHash    string    `json:"content_hash"`    // For integrity
    ContentType    string    `json:"content_type"`    // For categorization
    EncryptedFor   []string  `json:"encrypted_for"`   // For access control
    Timestamp      time.Time `json:"timestamp"`       // For ordering
    
    // Optional fields (privacy-preserving)
    AgentHash      string    `json:"agent_hash,omitempty"`      // Hash instead of ID
    ProjectHash    string    `json:"project_hash,omitempty"`    // Hash instead of name
    ApproxSize     int       `json:"approx_size,omitempty"`     // Size range, not exact
}

func CreateMinimalMetadata(fullMetadata *UCXLMetadata) *MinimalMetadata {
    return &MinimalMetadata{
        ContentHash:  fullMetadata.Hash,
        ContentType:  fullMetadata.ContentType,
        EncryptedFor: fullMetadata.EncryptedFor,
        Timestamp:    fullMetadata.Timestamp.Truncate(time.Hour), // Hour precision only
        AgentHash:    hashString(fullMetadata.CreatorRole),
        ProjectHash:  hashString(fullMetadata.Address.Project),
        ApproxSize:   roundToNearestPowerOf2(fullMetadata.Size),
    }
}
```

#### Anonymization Techniques

**k-Anonymity for Agent Identification**:
```go
type AnonymizedAgent struct {
    RoleCategory  string `json:"role_category"`  // "developer", "architect", etc.
    TeamSize      string `json:"team_size"`      // "small", "medium", "large"  
    ExperienceLevel string `json:"experience"`   // "junior", "senior", "expert"
    Specialization string `json:"specialization"` // "backend", "frontend", etc.
}

func AnonymizeAgent(agentID string) *AnonymizedAgent {
    agent := getAgentInfo(agentID)
    
    return &AnonymizedAgent{
        RoleCategory:    generalizeRole(agent.Role),
        TeamSize:        generalizeTeamSize(agent.TeamSize), 
        ExperienceLevel: generalizeExperience(agent.YearsExperience),
        Specialization:  agent.Specialization,
    }
}
```

**Differential Privacy for Metrics**:
```go
func AddNoise(value float64, sensitivity float64, epsilon float64) float64 {
    // Laplace mechanism for differential privacy
    scale := sensitivity / epsilon
    noise := sampleLaplaceNoise(scale)
    return value + noise
}

func PublishPrivateMetrics(rawMetrics map[string]float64) map[string]float64 {
    privateMetrics := make(map[string]float64)
    
    for metric, value := range rawMetrics {
        // Apply differential privacy with ε = 1.0
        privateValue := AddNoise(value, 1.0, 1.0)
        privateMetrics[metric] = math.Max(0, privateValue) // Ensure non-negative
    }
    
    return privateMetrics
}
```

**Cross-References**:
- Data protection implementation: `pkg/dht/encrypted_storage.go`
- Privacy utilities: `pkg/privacy/` (future implementation)
- Classification: `pkg/ucxl/decision_publisher.go:ClassifyDecision()`

## Consensus Security

### Election Security Model

#### Attack-Resistant Election Design

**Election Integrity Measures**:
```yaml
election_security:
  cryptographic_verification:
    candidate_signatures: true       # All candidate proposals signed
    vote_signatures: true           # All votes cryptographically signed
    result_signatures: true         # Election results signed by participants
    
  consensus_requirements:
    minimum_participants: 3         # Minimum nodes for valid election
    majority_threshold: "50%+1"     # Majority required for decision
    timeout_protection: true       # Prevent indefinite elections
    
  anti_manipulation:
    vote_validation: true           # Validate all votes cryptographically
    double_voting_prevention: true # Prevent multiple votes per node
    candidate_verification: true   # Verify candidate eligibility
    result_auditing: true          # Audit election results
```

**Byzantine Fault Tolerance**:
```go
type ByzantineProtection struct {
    maxByzantineNodes int    // Maximum compromised nodes (f)
    minHonestNodes    int    // Minimum honest nodes (3f + 1)
    consensusThreshold int   // Votes needed for consensus
}

func NewByzantineProtection(totalNodes int) *ByzantineProtection {
    maxByzantine := (totalNodes - 1) / 3  // f = (n-1)/3
    minHonest := 3*maxByzantine + 1       // 3f + 1
    threshold := 2*maxByzantine + 1       // 2f + 1
    
    return &ByzantineProtection{
        maxByzantineNodes:  maxByzantine,
        minHonestNodes:     minHonest,
        consensusThreshold: threshold,
    }
}

func (bp *ByzantineProtection) ValidateElectionResult(votes []Vote) error {
    if len(votes) < bp.consensusThreshold {
        return fmt.Errorf("insufficient votes for consensus: need %d, got %d", 
            bp.consensusThreshold, len(votes))
    }
    
    // Count votes for each candidate
    voteCounts := make(map[string]int)
    for _, vote := range votes {
        if err := bp.validateVoteSignature(vote); err != nil {
            return fmt.Errorf("invalid vote signature: %w", err)
        }
        voteCounts[vote.CandidateID]++
    }
    
    // Check if any candidate has sufficient votes
    for candidate, count := range voteCounts {
        if count >= bp.consensusThreshold {
            return nil // Consensus achieved
        }
    }
    
    return fmt.Errorf("no candidate achieved consensus threshold")
}
```

#### Split Brain Prevention

**Admin Conflict Resolution**:
```go
type SplitBrainDetector struct {
    knownAdmins      map[string]*AdminInfo
    conflictResolver *ConflictResolver
    electionManager  *ElectionManager
}

type AdminInfo struct {
    NodeID      string
    LastSeen    time.Time
    HeartbeatSequence int64
    PublicKey   []byte
    Signature   []byte
}

func (sbd *SplitBrainDetector) DetectSplitBrain() error {
    // Check for multiple simultaneous admin claims
    activeAdmins := make([]*AdminInfo, 0)
    cutoff := time.Now().Add(-30 * time.Second) // 30s heartbeat timeout
    
    for _, admin := range sbd.knownAdmins {
        if admin.LastSeen.After(cutoff) {
            activeAdmins = append(activeAdmins, admin)
        }
    }
    
    if len(activeAdmins) <= 1 {
        return nil // No split brain
    }
    
    // Multiple admins detected - resolve conflict
    return sbd.resolveSplitBrain(activeAdmins)
}

func (sbd *SplitBrainDetector) resolveSplitBrain(admins []*AdminInfo) error {
    // Resolve based on heartbeat sequence numbers and election timestamps
    legitimateAdmin := sbd.selectLegitimateAdmin(admins)
    
    // Trigger new election excluding illegitimate admins
    return sbd.electionManager.TriggerElection(ElectionReasonSplitBrain, legitimateAdmin)
}
```

### Consensus Attack Mitigation

#### Long-Range Attack Protection

**Election History Validation**:
```yaml
election_history:
  checkpoint_frequency: 100          # Create checkpoint every 100 elections
  history_depth: 1000               # Maintain 1000 election history  
  signature_chain: true             # Chain of election result signatures
  merkle_tree_validation: true      # Merkle tree for history integrity
  
  attack_detection:
    fork_detection: true             # Detect alternative election chains
    timestamp_validation: true      # Validate election timestamps
    sequence_validation: true       # Validate election sequence numbers
    participant_consistency: true   # Validate participant consistency
```

**Checkpoint-Based Security**:
```go
type ElectionCheckpoint struct {
    ElectionNumber  int64     `json:"election_number"`
    ResultHash      string    `json:"result_hash"`
    ParticipantHash string    `json:"participant_hash"`
    Timestamp       time.Time `json:"timestamp"`
    Signatures      []string  `json:"signatures"` // Multi-party signatures
}

func CreateElectionCheckpoint(electionNumber int64, 
    results []ElectionResult) (*ElectionCheckpoint, error) {
    
    // Create Merkle tree of election results
    resultHashes := make([][]byte, len(results))
    for i, result := range results {
        hash := sha256.Sum256(result.Serialize())
        resultHashes[i] = hash[:]
    }
    merkleRoot := calculateMerkleRoot(resultHashes)
    
    // Hash participant list
    participantHash := hashParticipants(results)
    
    checkpoint := &ElectionCheckpoint{
        ElectionNumber:  electionNumber,
        ResultHash:      fmt.Sprintf("%x", merkleRoot),
        ParticipantHash: fmt.Sprintf("%x", participantHash),
        Timestamp:       time.Now(),
        Signatures:      make([]string, 0),
    }
    
    // Get signatures from multiple admin nodes
    signatures, err := collectCheckpointSignatures(checkpoint)
    if err != nil {
        return nil, fmt.Errorf("failed to collect signatures: %w", err)
    }
    
    checkpoint.Signatures = signatures
    return checkpoint, nil
}
```

#### Eclipse Attack Resistance

**Diverse Peer Selection**:
```go
type PeerDiversityManager struct {
    peerSelectionStrategy string
    geographicDiversity   bool
    organizationDiversity bool  
    versionDiversity     bool
    minimumPeerSet       int
}

func (pdm *PeerDiversityManager) SelectDiversePeers(
    availablePeers []peer.ID, count int) ([]peer.ID, error) {
    
    if len(availablePeers) < pdm.minimumPeerSet {
        return nil, fmt.Errorf("insufficient peers for diversity requirement")
    }
    
    // Group peers by diversity attributes
    peerGroups := pdm.groupPeersByAttributes(availablePeers)
    
    // Select peers ensuring diversity across groups
    selectedPeers := make([]peer.ID, 0, count)
    
    // Round-robin selection across groups
    for len(selectedPeers) < count && len(peerGroups) > 0 {
        for groupName, peers := range peerGroups {
            if len(peers) == 0 {
                delete(peerGroups, groupName)
                continue
            }
            
            // Select random peer from group
            peerIndex := rand.Intn(len(peers))
            selectedPeer := peers[peerIndex]
            selectedPeers = append(selectedPeers, selectedPeer)
            
            // Remove selected peer from group
            peerGroups[groupName] = append(peers[:peerIndex], peers[peerIndex+1:]...)
            
            if len(selectedPeers) >= count {
                break
            }
        }
    }
    
    return selectedPeers, nil
}
```

**Cross-References**:
- Consensus implementation: `pkg/election/election.go`
- Byzantine fault tolerance: `pkg/election/consensus.go` (future)
- Election security: `pkg/election/security.go` (future)

## Audit & Compliance

### Security Logging

#### Comprehensive Audit Trail

**Security Event Types**:
```yaml
security_events:
  authentication:
    - agent_login
    - agent_logout  
    - authentication_failure
    - role_assignment
    - role_change
    
  authorization:
    - access_granted
    - access_denied
    - privilege_escalation_attempt
    - unauthorized_decrypt_attempt
    
  cryptographic:
    - key_generation
    - key_rotation
    - key_compromise
    - encryption_operation
    - decryption_operation
    - signature_verification
    
  consensus:
    - election_triggered
    - candidate_proposed
    - vote_cast
    - election_completed
    - admin_changed
    - split_brain_detected
    
  data:
    - content_stored
    - content_retrieved
    - content_modified
    - content_deleted
    - metadata_access
    
  network:
    - peer_connected
    - peer_disconnected
    - connection_refused
    - rate_limit_exceeded
    - malicious_activity_detected
```

**Security Log Structure**:
```go
type SecurityEvent struct {
    EventID     string                 `json:"event_id"`
    EventType   string                 `json:"event_type"`
    Severity    string                 `json:"severity"` // critical, high, medium, low
    Timestamp   time.Time              `json:"timestamp"`
    NodeID      string                 `json:"node_id"`
    AgentID     string                 `json:"agent_id,omitempty"`
    Role        string                 `json:"role,omitempty"`
    Action      string                 `json:"action"`
    Resource    string                 `json:"resource,omitempty"`
    Result      string                 `json:"result"` // success, failure, denied
    Details     map[string]interface{} `json:"details"`
    IPAddress   string                 `json:"ip_address,omitempty"`
    UserAgent   string                 `json:"user_agent,omitempty"`
    Signature   string                 `json:"signature"` // Event signature for integrity
}

func LogSecurityEvent(eventType string, details map[string]interface{}) {
    event := SecurityEvent{
        EventID:   generateEventID(),
        EventType: eventType,
        Severity:  determineSeverity(eventType),
        Timestamp: time.Now(),
        NodeID:    getCurrentNodeID(),
        AgentID:   getCurrentAgentID(),
        Role:      getCurrentRole(),
        Details:   details,
        Result:    determineResult(details),
    }
    
    // Sign event for integrity
    event.Signature = signSecurityEvent(event)
    
    // Log to multiple destinations
    logToFile(event)
    logToSyslog(event) 
    logToSecuritySIEM(event)
    
    // Trigger alerts for critical events
    if event.Severity == "critical" {
        triggerSecurityAlert(event)
    }
}
```

#### Log Integrity Protection

**Tamper-Evident Logging**:
```go
type TamperEvidentLogger struct {
    logChain     []LogEntry
    merkleTree   *MerkleTree
    signatures   map[string][]byte
    checkpoint   *LogCheckpoint
    mutex        sync.RWMutex
}

type LogEntry struct {
    Index       int64           `json:"index"`
    Timestamp   time.Time       `json:"timestamp"`
    Event       SecurityEvent   `json:"event"`
    PreviousHash string         `json:"previous_hash"`
    Hash        string          `json:"hash"`
}

func (tel *TamperEvidentLogger) AppendLogEntry(event SecurityEvent) error {
    tel.mutex.Lock()
    defer tel.mutex.Unlock()
    
    // Create new log entry
    entry := LogEntry{
        Index:     int64(len(tel.logChain)) + 1,
        Timestamp: time.Now(),
        Event:     event,
    }
    
    // Calculate hash chain
    if len(tel.logChain) > 0 {
        entry.PreviousHash = tel.logChain[len(tel.logChain)-1].Hash
    }
    entry.Hash = tel.calculateEntryHash(entry)
    
    // Append to chain
    tel.logChain = append(tel.logChain, entry)
    
    // Update Merkle tree
    tel.merkleTree.AddLeaf([]byte(entry.Hash))
    
    // Create periodic checkpoints
    if entry.Index%100 == 0 {
        tel.createCheckpoint(entry.Index)
    }
    
    return nil
}

func (tel *TamperEvidentLogger) VerifyLogIntegrity() error {
    // Verify hash chain integrity
    for i := 1; i < len(tel.logChain); i++ {
        if tel.logChain[i].PreviousHash != tel.logChain[i-1].Hash {
            return fmt.Errorf("hash chain broken at index %d", i)
        }
        
        expectedHash := tel.calculateEntryHash(tel.logChain[i])
        if tel.logChain[i].Hash != expectedHash {
            return fmt.Errorf("hash mismatch at index %d", i)
        }
    }
    
    // Verify Merkle tree consistency
    return tel.merkleTree.VerifyConsistency()
}
```

### Compliance Framework

#### Regulatory Compliance

**GDPR Compliance**:
```yaml
gdpr_compliance:
  data_minimization:
    collect_minimum_data: true       # Only collect necessary data
    pseudonymization: true          # Pseudonymize personal data
    purpose_limitation: true        # Use data only for stated purpose
    
  individual_rights:
    right_to_access: true           # Provide data access
    right_to_rectification: true   # Allow data correction
    right_to_erasure: true         # Allow data deletion
    right_to_portability: true     # Provide data export
    
  security_measures:
    data_protection_by_design: true # Built-in privacy protection
    encryption_at_rest: true       # Encrypt stored data
    encryption_in_transit: true    # Encrypt transmitted data
    access_controls: true          # Strict access controls
    
  breach_notification:
    detection_capability: true     # Detect breaches quickly
    notification_timeline: "72h"  # Notify within 72 hours
    documentation: true           # Document all breaches
```

**SOX Compliance**:
```yaml
sox_compliance:
  internal_controls:
    segregation_of_duties: true    # Separate conflicting duties
    authorization_controls: true   # Require proper authorization
    documentation_requirements: true # Document all processes
    
  audit_requirements:
    comprehensive_logging: true    # Log all financial-relevant activities
    audit_trail_integrity: true   # Maintain tamper-evident logs
    regular_assessments: true     # Regular control assessments
    
  change_management:
    change_approval_process: true  # Formal change approval
    testing_requirements: true    # Test all changes
    rollback_procedures: true     # Document rollback procedures
```

#### Compliance Reporting

**Automated Compliance Reports**:
```go
type ComplianceReporter struct {
    logAnalyzer    *LogAnalyzer
    reportTemplates map[string]*ReportTemplate
    scheduledReports []ScheduledReport
}

func (cr *ComplianceReporter) GenerateComplianceReport(
    reportType string, startTime, endTime time.Time) (*ComplianceReport, error) {
    
    template, exists := cr.reportTemplates[reportType]
    if !exists {
        return nil, fmt.Errorf("unknown report type: %s", reportType)
    }
    
    // Analyze logs for compliance metrics
    events, err := cr.logAnalyzer.GetEventsInTimeRange(startTime, endTime)
    if err != nil {
        return nil, fmt.Errorf("failed to retrieve events: %w", err)
    }
    
    // Calculate compliance metrics
    metrics := cr.calculateComplianceMetrics(events, template.RequiredMetrics)
    
    // Generate report
    report := &ComplianceReport{
        Type:        reportType,
        Period:      fmt.Sprintf("%s to %s", startTime.Format(time.RFC3339), endTime.Format(time.RFC3339)),
        Generated:   time.Now(),
        Metrics:     metrics,
        Violations:  cr.identifyViolations(events, template.ComplianceRules),
        Recommendations: cr.generateRecommendations(metrics),
    }
    
    return report, nil
}
```

**Cross-References**:
- Audit implementation: `pkg/audit/` (future implementation)
- Compliance framework: `pkg/compliance/` (future implementation)  
- Security logging: `pkg/security/logging.go` (future implementation)

## Security Operations

### Incident Response

#### Security Incident Classification

**Incident Severity Levels**:
```yaml
incident_classification:
  critical:
    description: "Immediate threat to system security or data integrity"
    examples:
      - admin_key_compromise
      - multiple_node_compromise  
      - encryption_algorithm_break
      - consensus_failure
    response_time: "15 minutes"
    escalation: "immediate"
    
  high:
    description: "Significant security event requiring prompt attention"
    examples:
      - role_key_compromise
      - unauthorized_admin_access_attempt
      - split_brain_condition
      - byzantine_behavior_detected
    response_time: "1 hour"
    escalation: "within_4_hours"
    
  medium:
    description: "Security event requiring investigation"
    examples:
      - repeated_authentication_failures
      - suspicious_peer_behavior
      - rate_limiting_triggered
      - configuration_tampering_attempt
    response_time: "4 hours"
    escalation: "within_24_hours"
    
  low:
    description: "Security event for monitoring and trend analysis"  
    examples:
      - normal_authentication_failures
      - expected_network_disconnections
      - routine_key_rotations
    response_time: "24 hours"
    escalation: "if_pattern_emerges"
```

#### Automated Incident Response

**Response Automation**:
```go
type IncidentResponseSystem struct {
    alertManager     *AlertManager
    responseHandlers map[string]ResponseHandler
    escalationRules  []EscalationRule
    notificationSvc  *NotificationService
}

type SecurityIncident struct {
    IncidentID   string
    Type         string
    Severity     string
    Description  string
    AffectedNodes []string
    Evidence     []SecurityEvent
    Status       string
    CreatedAt    time.Time
    UpdatedAt    time.Time
}

func (irs *IncidentResponseSystem) HandleSecurityEvent(event SecurityEvent) error {
    // Classify incident severity
    incident := irs.classifyIncident(event)
    if incident == nil {
        return nil // Not an incident
    }
    
    // Execute automated response
    handler, exists := irs.responseHandlers[incident.Type]
    if exists {
        err := handler.Handle(incident)
        if err != nil {
            log.Printf("Automated response failed: %v", err)
        }
    }
    
    // Send notifications
    irs.notificationSvc.NotifyIncident(incident)
    
    // Escalate if necessary
    irs.evaluateEscalation(incident)
    
    return nil
}

type KeyCompromiseHandler struct {
    keyManager   *KeyManager
    cryptoSystem *AgeCrypto
}

func (kch *KeyCompromiseHandler) Handle(incident *SecurityIncident) error {
    // Immediately rotate affected keys
    affectedRole := incident.Evidence[0].Role
    
    log.Printf("Initiating emergency key rotation for role: %s", affectedRole)
    
    // Generate new keys
    newKeys, err := kch.keyManager.GenerateRoleKeys(affectedRole)
    if err != nil {
        return fmt.Errorf("emergency key generation failed: %w", err)
    }
    
    // Update role configuration
    err = kch.keyManager.EmergencyKeyRotation(affectedRole, newKeys)
    if err != nil {
        return fmt.Errorf("emergency key rotation failed: %w", err)
    }
    
    // Re-encrypt recent content
    err = kch.cryptoSystem.ReEncryptRecentContent(affectedRole, newKeys, 24*time.Hour)
    if err != nil {
        log.Printf("Re-encryption warning: %v", err) // Non-fatal
    }
    
    // Revoke old keys immediately
    kch.keyManager.RevokeKeys(affectedRole, "emergency_compromise")
    
    log.Printf("Emergency key rotation completed for role: %s", affectedRole)
    return nil
}
```

### Security Monitoring

#### Real-Time Security Monitoring

**Security Metrics Dashboard**:
```yaml
security_metrics:
  authentication:
    - failed_login_attempts
    - successful_logins
    - role_changes
    - privilege_escalations
    
  authorization: 
    - access_denials
    - unauthorized_attempts
    - role_violations
    - permission_escalations
    
  cryptographic:
    - encryption_failures
    - decryption_failures
    - key_operations
    - signature_verifications
    
  network:
    - connection_failures
    - peer_blacklistings
    - rate_limit_hits
    - ddos_attempts
    
  consensus:
    - election_frequency
    - failed_elections
    - split_brain_events
    - byzantine_detections
```

**Anomaly Detection**:
```go
type AnomalyDetector struct {
    baselineMetrics map[string]*MetricBaseline
    alertThresholds map[string]float64
    mlModel        *AnomalyModel
}

type MetricBaseline struct {
    Mean          float64
    StdDeviation  float64
    SampleSize    int64
    LastUpdated   time.Time
}

func (ad *AnomalyDetector) DetectAnomalies(metrics map[string]float64) []Anomaly {
    anomalies := make([]Anomaly, 0)
    
    for metricName, currentValue := range metrics {
        baseline, exists := ad.baselineMetrics[metricName]
        if !exists {
            continue // No baseline yet
        }
        
        // Calculate z-score
        zScore := (currentValue - baseline.Mean) / baseline.StdDeviation
        
        // Check if anomalous (outside 3 standard deviations)
        if math.Abs(zScore) > 3.0 {
            severity := "high"
            if math.Abs(zScore) > 5.0 {
                severity = "critical"
            }
            
            anomaly := Anomaly{
                MetricName:   metricName,
                CurrentValue: currentValue,
                BaselineValue: baseline.Mean,
                ZScore:       zScore,
                Severity:     severity,
                DetectedAt:   time.Now(),
            }
            anomalies = append(anomalies, anomaly)
        }
    }
    
    return anomalies
}
```

#### Security Intelligence

**Threat Intelligence Integration**:
```yaml
threat_intelligence:
  sources:
    - internal_logs          # Internal security event analysis
    - peer_reputation        # P2P peer reputation data
    - external_feeds         # External threat intelligence feeds
    - vulnerability_databases # CVE and vulnerability data
    
  indicators:
    - malicious_peer_ids     # Known malicious peer identifiers
    - attack_signatures      # Network attack signatures  
    - compromised_keys       # Known compromised cryptographic keys
    - malicious_content_hashes # Hash signatures of malicious content
    
  automated_response:
    - blacklist_peers        # Automatically blacklist malicious peers
    - block_content          # Block known malicious content
    - update_signatures      # Update detection signatures
    - alert_operators        # Alert security operators
```

**Security Orchestration**:
```go
type SecurityOrchestrator struct {
    threatIntelligence *ThreatIntelligence
    incidentResponse   *IncidentResponseSystem
    anomalyDetector    *AnomalyDetector
    alertManager       *AlertManager
}

func (so *SecurityOrchestrator) ProcessSecurityData(data SecurityData) {
    // 1. Analyze for known threats
    threats := so.threatIntelligence.AnalyzeData(data)
    for _, threat := range threats {
        so.incidentResponse.HandleThreat(threat)
    }
    
    // 2. Detect anomalies
    anomalies := so.anomalyDetector.DetectAnomalies(data.Metrics)
    for _, anomaly := range anomalies {
        so.alertManager.SendAnomalyAlert(anomaly)
    }
    
    // 3. Update threat intelligence
    so.threatIntelligence.UpdateWithNewData(data)
    
    // 4. Generate security reports
    if so.shouldGenerateReport(data) {
        report := so.generateSecurityReport(data)
        so.alertManager.SendSecurityReport(report)
    }
}
```

**Cross-References**:
- Security operations: `pkg/security/` (future implementation)
- Monitoring implementation: [MONITORING.md](MONITORING.md#security-monitoring)
- Incident response procedures: `docs/incident_response_playbook.md` (future)

---

## Cross-References

- **Architecture**: [ARCHITECTURE.md](ARCHITECTURE.md) - System architecture
- **User Manual**: [USER_MANUAL.md](USER_MANUAL.md) - Security best practices
- **Developer Guide**: [DEVELOPER.md](DEVELOPER.md) - Security development  
- **API Reference**: [API_REFERENCE.md](API_REFERENCE.md) - Security APIs
- **Configuration**: [CONFIG_REFERENCE.md](CONFIG_REFERENCE.md) - Security config
- **Implementation**: `pkg/crypto/`, `pkg/election/`, `pkg/config/` - Source code

**BZZZ Security Model v2.0** - Complete security architecture for Phase 2B unified platform with Age encryption and distributed consensus security.