# Security Manager Component Specification

**Component ID:** C-SEC-001  
**Component Name:** Security Manager  
**Version:** 1.0  
**Date:** 2025-02-01  

## 1. Component Overview

### 1.1 Purpose
The Security Manager is responsible for implementing comprehensive security mechanisms to protect the system against unauthorized access, malicious firmware, and data breaches. It provides centralized security policy enforcement, cryptographic operations, and security violation handling across all system components.

### 1.2 Scope
- Secure boot process management and enforcement
- Flash encryption and secure storage management
- Communication security with TLS/mTLS implementation
- Cryptographic key management and protection
- Security violation detection and response
- Access control and authentication services
- Security policy enforcement and compliance

### 1.3 Responsibilities
- Enforce secure boot verification for all firmware
- Manage flash encryption and secure storage access
- Provide cryptographic services for communication security
- Implement key management and certificate handling
- Detect and respond to security violations
- Maintain security policies and access control
- Coordinate security operations across system components

## 2. Component Architecture

### 2.1 Static View

```mermaid
graph TB
    subgraph "Security Manager"
        SM[Security Controller]
        SBC[Secure Boot Controller]
        FEM[Flash Encryption Manager]
        TM[TLS Manager]
        KM[Key Manager]
        SVH[Security Violation Handler]
        ACM[Access Control Manager]
    end
    
    subgraph "Cryptographic Services"
        CM[Crypto Manager]
        CA[Certificate Authority]
        RNG[Random Number Generator]
        HSM[Hardware Security Module]
    end
    
    subgraph "Hardware Security"
        EFUSE[eFuse Manager]
        SBH[Secure Boot Hardware]
        FEH[Flash Encryption Hardware]
        HWRNG[Hardware RNG]
    end
    
    SM --> SBC
    SM --> FEM
    SM --> TM
    SM --> KM
    SM --> SVH
    SM --> ACM
    
    SBC --> SBH
    FEM --> FEH
    TM --> CM
    TM --> CA
    KM --> HSM
    KM --> EFUSE
    CM --> RNG
    RNG --> HWRNG
```

### 2.2 Internal Components

#### 2.2.1 Security Controller
- Central coordination of security operations
- Security policy enforcement and compliance
- Security state management and monitoring

#### 2.2.2 Secure Boot Controller
- Secure boot process management
- Firmware signature verification
- Boot failure handling and recovery

#### 2.2.3 Flash Encryption Manager
- Flash encryption configuration and management
- Secure storage access control
- Encryption key derivation and management

#### 2.2.4 TLS Manager
- TLS/mTLS session management
- Certificate validation and handling
- Secure communication channel establishment

#### 2.2.5 Key Manager
- Cryptographic key lifecycle management
- Key storage and protection
- Key derivation and rotation

#### 2.2.6 Security Violation Handler
- Security violation detection and classification
- Incident response and recovery
- Security event logging and reporting

#### 2.2.7 Access Control Manager
- Authentication and authorization services
- Role-based access control
- Session management and validation

## 3. Interfaces

### 3.1 Provided Interfaces

#### 3.1.1 ISecurityManager
```cpp
class ISecurityManager {
public:
    virtual ~ISecurityManager() = default;
    
    // Security Lifecycle
    virtual Result<void> initialize() = 0;
    virtual Result<void> shutdown() = 0;
    virtual SecurityStatus getSecurityStatus() const = 0;
    
    // Secure Boot Management
    virtual Result<void> validateFirmwareSignature(const FirmwareImage& firmware) = 0;
    virtual Result<void> enableSecureBoot() = 0;
    virtual bool isSecureBootEnabled() const = 0;
    virtual SecureBootStatus getSecureBootStatus() const = 0;
    
    // Flash Encryption Management
    virtual Result<void> enableFlashEncryption() = 0;
    virtual bool isFlashEncryptionEnabled() const = 0;
    virtual Result<void> encryptFlashRegion(FlashRegion region) = 0;
    virtual Result<void> decryptFlashRegion(FlashRegion region) = 0;
    
    // Communication Security
    virtual Result<TLSSession> establishSecureConnection(const ConnectionParams& params) = 0;
    virtual Result<void> validateCertificate(const Certificate& certificate) = 0;
    virtual Result<void> terminateSecureConnection(TLSSessionId session_id) = 0;
    
    // Key Management
    virtual Result<KeyHandle> generateKey(KeyType type, KeyUsage usage) = 0;
    virtual Result<void> storeKey(KeyHandle handle, const SecureStorage& storage) = 0;
    virtual Result<void> deleteKey(KeyHandle handle) = 0;
    virtual Result<void> rotateKey(KeyHandle handle) = 0;
    
    // Access Control
    virtual Result<SessionId> authenticateUser(const Credentials& credentials) = 0;
    virtual Result<bool> authorizeOperation(SessionId session, Operation operation) = 0;
    virtual Result<void> terminateSession(SessionId session) = 0;
    
    // Security Violations
    virtual Result<void> reportSecurityViolation(const SecurityViolation& violation) = 0;
    virtual std::vector<SecurityViolation> getSecurityViolations() const = 0;
    virtual Result<void> clearSecurityViolations() = 0;
};
```

#### 3.1.2 ICryptoManager
```cpp
class ICryptoManager {
public:
    virtual ~ICryptoManager() = default;
    
    // Symmetric Encryption
    virtual Result<std::vector<uint8_t>> encrypt(const std::vector<uint8_t>& data,
                                                const SymmetricKey& key) = 0;
    virtual Result<std::vector<uint8_t>> decrypt(const std::vector<uint8_t>& data,
                                                const SymmetricKey& key) = 0;
    
    // Asymmetric Encryption
    virtual Result<std::vector<uint8_t>> encryptAsymmetric(const std::vector<uint8_t>& data,
                                                          const PublicKey& key) = 0;
    virtual Result<std::vector<uint8_t>> decryptAsymmetric(const std::vector<uint8_t>& data,
                                                          const PrivateKey& key) = 0;
    
    // Digital Signatures
    virtual Result<Signature> sign(const std::vector<uint8_t>& data,
                                  const PrivateKey& key) = 0;
    virtual Result<bool> verify(const std::vector<uint8_t>& data,
                               const Signature& signature,
                               const PublicKey& key) = 0;
    
    // Hash Functions
    virtual Result<Hash> calculateSHA256(const std::vector<uint8_t>& data) = 0;
    virtual Result<Hash> calculateHMAC(const std::vector<uint8_t>& data,
                                      const SymmetricKey& key) = 0;
    
    // Random Number Generation
    virtual Result<std::vector<uint8_t>> generateRandomBytes(size_t length) = 0;
    virtual Result<uint32_t> generateRandomNumber() = 0;
};
```

#### 3.1.3 IKeyManager
```cpp
class IKeyManager {
public:
    virtual ~IKeyManager() = default;
    
    // Key Generation
    virtual Result<KeyHandle> generateSymmetricKey(SymmetricKeyType type) = 0;
    virtual Result<KeyPair> generateAsymmetricKeyPair(AsymmetricKeyType type) = 0;
    virtual Result<KeyHandle> deriveKey(const KeyDerivationParams& params) = 0;
    
    // Key Storage
    virtual Result<void> storeKey(KeyHandle handle, const SecureStorage& storage) = 0;
    virtual Result<KeyHandle> loadKey(const KeyIdentifier& identifier) = 0;
    virtual Result<void> deleteKey(KeyHandle handle) = 0;
    
    // Key Operations
    virtual Result<void> rotateKey(KeyHandle handle) = 0;
    virtual Result<void> backupKey(KeyHandle handle, const BackupParams& params) = 0;
    virtual Result<void> restoreKey(const BackupData& backup) = 0;
    
    // Key Information
    virtual Result<KeyInfo> getKeyInfo(KeyHandle handle) const = 0;
    virtual std::vector<KeyIdentifier> listKeys() const = 0;
    virtual bool isKeyValid(KeyHandle handle) const = 0;
};
```

### 3.2 Required Interfaces

#### 3.2.1 IDiagnosticsManager
- Security violation reporting and logging
- Security event documentation
- Security metrics collection

#### 3.2.2 IPersistenceManager
- Secure storage of certificates and keys
- Security configuration persistence
- Audit log storage

#### 3.2.3 ISystemStateManager
- Security state coordination
- Boot failure state management
- Security-related state transitions

#### 3.2.4 IEventSystem
- Security event publication
- Security alert notifications
- Asynchronous security event handling

## 4. Dynamic View

### 4.1 Secure Boot Sequence

```mermaid
sequenceDiagram
    participant PWR as Power On
    participant ROM as ROM Bootloader
    participant SBC as Secure Boot Controller
    participant BV as Boot Validator
    participant ARB as Anti-Rollback Manager
    participant APP as Application
    participant SVH as Security Violation Handler
    
    PWR->>ROM: System Reset
    ROM->>SBC: initializeSecureBoot()
    SBC->>BV: validateFirmwareSignature()
    BV->>BV: verifyRSA3072Signature()
    BV->>ARB: checkAntiRollback()
    ARB-->>BV: version_check_result
    
    alt Signature Valid and Version OK
        BV-->>SBC: validation_success
        SBC->>APP: jumpToApplication()
    else Validation Failed
        BV-->>SBC: validation_failed
        SBC->>SVH: reportSecurityViolation(BOOT_FAILURE)
        SBC->>SBC: enterBootFailureState()
    end
```

### 4.2 TLS Connection Establishment Sequence

```mermaid
sequenceDiagram
    participant APP as Application
    participant TM as TLS Manager
    participant CA as Certificate Authority
    participant KM as Key Manager
    participant CM as Crypto Manager
    participant MH as Main Hub
    
    APP->>TM: establishSecureConnection(main_hub_params)
    TM->>KM: getDeviceCertificate()
    KM-->>TM: device_certificate
    TM->>KM: getDevicePrivateKey()
    KM-->>TM: device_private_key
    
    TM->>MH: TLS_ClientHello + Certificate
    MH->>TM: TLS_ServerHello + Certificate
    
    TM->>CA: validateServerCertificate(server_cert)
    CA->>CA: verifyCertificateChain()
    CA-->>TM: certificate_validation_result
    
    alt Certificate Valid
        TM->>CM: generateSessionKeys()
        CM-->>TM: session_keys
        TM->>TM: establishSecureChannel()
        TM-->>APP: secure_connection_established
    else Certificate Invalid
        TM->>SVH: reportSecurityViolation(CERT_VALIDATION_FAILED)
        TM-->>APP: connection_failed
    end
```

### 4.3 Security Violation Handling Sequence

```mermaid
sequenceDiagram
    participant COMP as System Component
    participant SVH as Security Violation Handler
    participant SM as Security Manager
    participant DIAG as Diagnostics Manager
    participant STM as System State Manager
    participant ES as Event System
    
    COMP->>SVH: reportSecurityViolation(violation)
    SVH->>SVH: classifyViolation(violation)
    SVH->>DIAG: logSecurityEvent(violation)
    
    alt Critical Violation
        SVH->>STM: transitionToSecureState()
        SVH->>ES: publishCriticalSecurityAlert(violation)
        SVH->>SM: implementSecurityMeasures()
    else Non-Critical Violation
        SVH->>ES: publishSecurityWarning(violation)
        SVH->>SM: updateSecurityMetrics()
    end
    
    SVH->>SVH: updateViolationHistory()
    SVH-->>COMP: violation_handled
```

## 5. Security Policies and Configuration

### 5.1 Security Policy Structure
```cpp
struct SecurityPolicy {
    // Secure Boot Policy
    SecureBootPolicy secure_boot;
    
    // Flash Encryption Policy
    FlashEncryptionPolicy flash_encryption;
    
    // Communication Security Policy
    CommunicationSecurityPolicy communication;
    
    // Key Management Policy
    KeyManagementPolicy key_management;
    
    // Access Control Policy
    AccessControlPolicy access_control;
    
    // Violation Response Policy
    ViolationResponsePolicy violation_response;
};
```

### 5.2 Secure Boot Configuration
```cpp
struct SecureBootPolicy {
    bool enabled;
    SignatureAlgorithm signature_algorithm;  // RSA-3072 or ECDSA-P256
    bool anti_rollback_enabled;
    uint32_t minimum_security_version;
    std::vector<PublicKey> trusted_keys;
    BootFailureAction failure_action;
};
```

### 5.3 Flash Encryption Configuration
```cpp
struct FlashEncryptionPolicy {
    bool enabled;
    EncryptionAlgorithm algorithm;  // AES-256
    EncryptionMode mode;           // Release or Development
    std::vector<FlashRegion> encrypted_regions;
    KeyDerivationMethod key_derivation;
    bool external_storage_encryption;
};
```

### 5.4 Communication Security Configuration
```cpp
struct CommunicationSecurityPolicy {
    TLSVersion minimum_tls_version;  // TLS 1.2
    bool mutual_authentication_required;
    std::vector<Certificate> trusted_ca_certificates;
    CertificateValidationLevel validation_level;
    CipherSuite allowed_cipher_suites;
    uint32_t session_timeout_seconds;
};
```

## 6. Cryptographic Operations

### 6.1 Supported Algorithms
```cpp
namespace CryptoAlgorithms {
    // Symmetric Encryption
    constexpr const char* AES_256_GCM = "AES-256-GCM";
    constexpr const char* AES_256_CBC = "AES-256-CBC";
    
    // Asymmetric Encryption
    constexpr const char* RSA_3072 = "RSA-3072";
    constexpr const char* ECDSA_P256 = "ECDSA-P256";
    
    // Hash Functions
    constexpr const char* SHA_256 = "SHA-256";
    constexpr const char* SHA_512 = "SHA-512";
    
    // Key Derivation
    constexpr const char* PBKDF2 = "PBKDF2";
    constexpr const char* HKDF = "HKDF";
}
```

### 6.2 Key Management
```cpp
class SecureKeyManager {
public:
    // Key Types
    enum class KeyType {
        SYMMETRIC_AES_256,
        ASYMMETRIC_RSA_3072,
        ASYMMETRIC_ECDSA_P256,
        DEVICE_IDENTITY,
        SESSION_KEY,
        ENCRYPTION_KEY
    };
    
    // Key Storage Locations
    enum class KeyStorage {
        EFUSE,              // One-time programmable secure storage
        ENCRYPTED_FLASH,    // Encrypted flash storage
        HARDWARE_HSM,       // Hardware security module
        VOLATILE_MEMORY     // Temporary storage in RAM
    };
    
    // Key Operations
    Result<KeyHandle> generateKey(KeyType type, KeyStorage storage);
    Result<void> rotateKey(KeyHandle handle);
    Result<void> revokeKey(KeyHandle handle);
    Result<KeyInfo> getKeyInfo(KeyHandle handle) const;
};
```

## 7. Certificate Management

### 7.1 Certificate Types
```cpp
enum class CertificateType {
    DEVICE_IDENTITY,        // Unique device certificate
    CA_ROOT,               // Root CA certificate
    CA_INTERMEDIATE,       // Intermediate CA certificate
    SERVER_CERTIFICATE,    // Server authentication certificate
    CLIENT_CERTIFICATE     // Client authentication certificate
};
```

### 7.2 Certificate Validation
```cpp
class CertificateValidator {
public:
    struct ValidationResult {
        bool is_valid;
        std::vector<ValidationError> errors;
        CertificateInfo certificate_info;
    };
    
    ValidationResult validateCertificate(const Certificate& certificate) const;
    ValidationResult validateCertificateChain(const CertificateChain& chain) const;
    ValidationResult checkCertificateRevocation(const Certificate& certificate) const;
    bool isCertificateExpired(const Certificate& certificate) const;
    bool isCertificateTrusted(const Certificate& certificate) const;
};
```

## 8. Security Violation Management

### 8.1 Violation Types
```cpp
enum class SecurityViolationType {
    // Boot Security Violations
    SECURE_BOOT_FAILURE,
    FIRMWARE_SIGNATURE_INVALID,
    ANTI_ROLLBACK_VIOLATION,
    
    // Communication Security Violations
    TLS_HANDSHAKE_FAILURE,
    CERTIFICATE_VALIDATION_FAILURE,
    MESSAGE_INTEGRITY_VIOLATION,
    
    // Access Control Violations
    AUTHENTICATION_FAILURE,
    AUTHORIZATION_FAILURE,
    SESSION_HIJACKING_ATTEMPT,
    
    // Cryptographic Violations
    KEY_COMPROMISE_DETECTED,
    ENCRYPTION_FAILURE,
    SIGNATURE_VERIFICATION_FAILURE,
    
    // Physical Security Violations
    TAMPER_DETECTION,
    SIDE_CHANNEL_ATTACK,
    FAULT_INJECTION_DETECTED
};
```

### 8.2 Violation Response Actions
```cpp
enum class ViolationResponseAction {
    LOG_ONLY,               // Log the violation but continue operation
    ALERT_AND_CONTINUE,     // Send alert and continue with monitoring
    DEGRADE_FUNCTIONALITY,  // Reduce system functionality
    ISOLATE_COMPONENT,      // Isolate affected component
    SYSTEM_SHUTDOWN,        // Controlled system shutdown
    EMERGENCY_LOCKDOWN      // Immediate system lockdown
};
```

### 8.3 Violation Handling
```cpp
class SecurityViolationHandler {
public:
    void reportViolation(const SecurityViolation& violation);
    void handleViolation(const SecurityViolation& violation);
    std::vector<SecurityViolation> getViolationHistory() const;
    SecurityMetrics getSecurityMetrics() const;
    
private:
    ViolationResponseAction determineResponse(SecurityViolationType type) const;
    void executeResponse(ViolationResponseAction action, const SecurityViolation& violation);
    void updateSecurityState(const SecurityViolation& violation);
};
```

## 9. Hardware Security Integration

### 9.1 eFuse Management
```cpp
class eFuseManager {
public:
    // eFuse Operations
    Result<void> burneFuse(eFuseField field, const std::vector<uint8_t>& data);
    Result<std::vector<uint8_t>> readeFuse(eFuseField field) const;
    bool iseFuseBurned(eFuseField field) const;
    
    // Security Version Management
    Result<void> setSecurityVersion(uint32_t version);
    uint32_t getSecurityVersion() const;
    bool isVersionRollbackAllowed(uint32_t target_version) const;
    
    // Key Management
    Result<void> burnEncryptionKey(const EncryptionKey& key);
    Result<void> burnSigningKey(const PublicKey& key);
    bool isKeyBurned(KeyType type) const;
};
```

### 9.2 Hardware Security Module Integration
```cpp
class HardwareSecurityModule {
public:
    // Cryptographic Operations
    Result<std::vector<uint8_t>> performCryptoOperation(
        CryptoOperation operation,
        const std::vector<uint8_t>& input,
        const CryptoParams& params) const;
    
    // Key Operations
    Result<KeyHandle> generateSecureKey(KeyType type);
    Result<void> storeSecureKey(KeyHandle handle, const SecureKey& key);
    Result<void> deleteSecureKey(KeyHandle handle);
    
    // Random Number Generation
    Result<std::vector<uint8_t>> generateTrueRandomBytes(size_t length) const;
    
    // Attestation
    Result<AttestationReport> generateAttestation() const;
    Result<bool> verifyAttestation(const AttestationReport& report) const;
};
```

## 10. Performance and Resource Management

### 10.1 Performance Characteristics
- **Secure Boot Validation**: < 5 seconds during boot
- **TLS Handshake**: < 10 seconds for connection establishment
- **Cryptographic Operations**: Hardware-accelerated when available
- **Key Operations**: < 100ms for typical key operations
- **Certificate Validation**: < 2 seconds for certificate chain validation

### 10.2 Resource Usage
- **Memory**: < 32KB for security operations and buffers
- **Storage**: Variable based on certificate and key storage requirements
- **CPU**: Hardware acceleration utilized when available
- **Power**: Optimized for low-power operation

## 11. Error Handling and Recovery

### 11.1 Error Categories
- **Cryptographic Errors**: Key generation failures, encryption/decryption errors
- **Certificate Errors**: Certificate validation failures, expiration errors
- **Hardware Errors**: HSM failures, eFuse access errors
- **Communication Errors**: TLS handshake failures, connection errors
- **Configuration Errors**: Invalid security policy configuration

### 11.2 Recovery Strategies
- **Graceful Degradation**: Reduce security level while maintaining operation
- **Fallback Mechanisms**: Use alternative security methods when primary fails
- **Error Isolation**: Isolate security failures to prevent system-wide impact
- **Recovery Procedures**: Automated recovery from transient security failures

## 12. Compliance and Standards

### 12.1 Security Standards
- **FIPS 140-2**: Cryptographic module validation
- **Common Criteria**: Security evaluation criteria
- **IEC 62443**: Industrial communication networks security
- **ISO/IEC 27001**: Information security management

### 12.2 Cryptographic Standards
- **NIST SP 800-series**: Cryptographic guidelines and recommendations
- **RFC 5280**: X.509 certificate and CRL profile
- **RFC 8446**: TLS 1.3 specification
- **PKCS standards**: Public key cryptography standards

## 13. Testing Strategy

### 13.1 Security Testing
- **Penetration Testing**: Simulated attacks and vulnerability assessment
- **Cryptographic Testing**: Algorithm implementation validation
- **Certificate Testing**: Certificate validation and chain verification
- **Protocol Testing**: TLS/mTLS implementation testing

### 13.2 Compliance Testing
- **Standards Compliance**: Verification against security standards
- **Interoperability Testing**: Compatibility with external systems
- **Performance Testing**: Security operation performance validation
- **Stress Testing**: Security under high load and attack conditions

## 14. Dependencies

### 14.1 Internal Dependencies
- Diagnostics Manager for security event logging
- System State Manager for security state coordination
- Persistence Manager for secure storage operations
- Communication Manager for secure communication

### 14.2 External Dependencies
- ESP-IDF security APIs (Secure Boot, Flash Encryption)
- mbedTLS cryptographic library
- Hardware security features (eFuse, HSM, Hardware RNG)
- Certificate authority infrastructure

## 15. Constraints and Assumptions

### 15.1 Constraints
- Hardware security features must be properly configured
- Cryptographic operations limited by available hardware acceleration
- Key storage limited by eFuse and secure storage capacity
- Security operations must not significantly impact system performance

### 15.2 Assumptions
- Proper hardware security configuration during manufacturing
- Valid certificates and keys provisioned during deployment
- Secure communication channels available for key exchange
- Sufficient system resources for security operations
- Proper physical security of the device deployment environment