# Sudarshan Engine Architecture

## Overview

Sudarshan Engine is a universal quantum-safe cybersecurity engine designed to protect any digital asset or application against current and future threats, including quantum computing attacks. The engine implements a "Box-in-a-Box" layered security model with post-quantum cryptography (PQC) at its core.

## Core Principles

- **Quantum-Safe**: All cryptographic operations use NIST-standard PQC algorithms
- **Zero Trust**: Every access requires explicit authentication and authorization
- **Stateless Operations**: No key reuse; all operations are one-time and ephemeral
- **Hardware Isolation**: Sensitive operations occur in secure enclaves when available
- **Fail-Fast**: Immediate termination on any validation failure
- **Open-Core**: Free access to core functionality; premium features for enterprise

## Box-in-a-Box Security Model

The engine implements four concentric layers of security, each providing independent protection against different attack vectors:

### Layer 1: Inner Shield (PQC Wallet Wrapper)

**Purpose**: Encases legacy or sensitive assets in a quantum-safe wrapper, abstracting original cryptography.

**Components**:
- PQC key encapsulation (Kyber)
- Legacy asset abstraction layer
- Stateless key derivation

**Critical Features**:
- Forbids direct access to original key material
- Requires PQC-validated channels for all operations
- Maintains compatibility with existing systems

**Implementation**:
```python
class InnerShield:
    def wrap_asset(self, legacy_key, metadata):
        # Generate PQC keypair
        kem = Kyber1024()
        public_key, secret_key = kem.keypair()

        # Derive session key
        session_key = kem.encapsulate(public_key)

        # Encrypt legacy key with session key
        encrypted_legacy = aes_encrypt(legacy_key, session_key)

        return {
            'pqc_public': public_key,
            'encrypted_legacy': encrypted_legacy,
            'metadata': metadata
        }
```

### Layer 2: Outer Vault (Multi-Factor PQC Vault)

**Purpose**: Adds quantum-resistant multi-factor authentication and vaulting capabilities.

**Components**:
- PQC digital signatures (Dilithium/Falcon)
- Multi-factor authentication (MFA)
- Password-based key derivation
- Hardware token integration

**Critical Features**:
- Strictly PQC-only cryptography (no legacy curves)
- At least two factors required (possession + knowledge/inherence)
- Quantum-resistant authentication

**Implementation**:
```python
class OuterVault:
    def authenticate(self, user_id, factors):
        # Verify PQC signatures from multiple factors
        for factor in factors:
            if not dilithium.verify(factor.signature, factor.challenge):
                raise AuthenticationError("Invalid PQC signature")

        # Generate vault session key
        session_key = hkdf_derive(factors, context="vault_session")
        return session_key
```

### Layer 3: Isolation Room (Hardware-Secured Gateway)

**Purpose**: Ensures all cryptographic operations occur within physically and logically isolated hardware environments.

**Components**:
- Hardware Security Module (HSM) integration
- Trusted Platform Module (TPM) support
- Secure Enclave (SGX/TEE) utilization
- Remote attestation

**Critical Features**:
- Blocks all side-channel and remote attacks
- No untrusted process handles keys outside enclave
- Hardware attestation for all operations

**Implementation**:
```python
class IsolationRoom:
    def execute_in_enclave(self, operation, data):
        # Verify enclave attestation
        if not self.verify_attestation():
            raise SecurityError("Enclave attestation failed")

        # Execute operation in secure environment
        result = enclave.execute(operation, data)

        # Verify result integrity
        if not self.verify_result_integrity(result):
            raise SecurityError("Result integrity check failed")

        return result
```

### Layer 4: Transaction Capsule (One-Time PQC Containers)

**Purpose**: Creates unique, single-use transaction containers that are derived, signed, and destroyed in one operation.

**Components**:
- Unique PQC key generation per transaction
- Stateless transaction processing
- One-time signature schemes
- Transaction compartmentalization

**Critical Features**:
- Absolute non-reuse of keys and addresses
- Fresh PQC signatures for each output
- Stateless operation design
- Replay attack prevention

**Implementation**:
```python
class TransactionCapsule:
    def create_transaction(self, payload, recipient):
        # Generate unique transaction keypair
        tx_keypair = dilithium.keypair()

        # Create transaction capsule
        capsule = {
            'id': generate_unique_id(),
            'payload': payload,
            'recipient': recipient,
            'timestamp': current_time(),
            'public_key': tx_keypair.public_key
        }

        # Sign capsule with transaction key
        signature = dilithium.sign(tx_keypair.secret_key, capsule)

        # Destroy secret key immediately
        del tx_keypair.secret_key

        return {
            'capsule': capsule,
            'signature': signature
        }
```

## System Components

### .spq File Format

The proprietary .spq format provides quantum-safe storage for encrypted data:

**Structure**:
```
[ MAGIC BYTES  ]  "SUDARSHA" (8 bytes)
[ HEADER       ]  version, algo, compression, lengths
[ METADATA     ]  JSON/CBOR human-readable info
[ ENCRYPTED PAYLOAD ]  Kyber KEM + AES/ChaCha20
[ HASH + SIGNATURE ]  SHA3-512 + Dilithium/Falcon
```

**Security Properties**:
- Quantum-resistant encryption
- Tamper-evident integrity
- Authenticated origin
- Self-describing format

### Core Engine

**Components**:
- **Crypto Engine**: PQC algorithm implementations
- **Key Management**: Ephemeral key generation and destruction
- **Protocol Handler**: Box-in-a-Box layer orchestration
- **Attestation Service**: Hardware and software integrity verification

**Architecture**:
```
┌─────────────────┐
│   Application   │
│   (CLI/SDK/GUI) │
└─────────────────┘
         │
┌─────────────────┐
│ Transaction     │ ← Layer 4
│ Capsule         │
└─────────────────┘
         │
┌─────────────────┐
│ Isolation Room  │ ← Layer 3
└─────────────────┘
         │
┌─────────────────┐
│ Outer Vault     │ ← Layer 2
└─────────────────┘
         │
┌─────────────────┐
│ Inner Shield    │ ← Layer 1
└─────────────────┘
         │
┌─────────────────┐
│   .spq Format   │
└─────────────────┘
         │
┌─────────────────┐
│  Crypto Engine  │
│  (liboqs + AES) │
└─────────────────┘
```

### Access Tiers

#### Free Tier (AGPL)
- CLI interface
- Desktop application
- Web interface
- Basic SDK
- Local .spq operations
- Community support

#### Premium Tier (Commercial)
- API access
- Cloud processing
- Advanced algorithms
- Enterprise integrations
- Priority support
- SLA guarantees

## Security Threat Model

### Attack Vectors Addressed

1. **Quantum Computing Attacks**
   - Shor's algorithm (key factorization)
   - Grover's algorithm (key search)
   - Mitigated by PQC algorithms

2. **Classical Attacks**
   - Man-in-the-middle
   - Replay attacks
   - Side-channel attacks
   - Mitigated by multi-layer design

3. **Implementation Attacks**
   - Fault injection
   - Power analysis
   - Timing attacks
   - Mitigated by hardware isolation

4. **Protocol Attacks**
   - Key reuse
   - Signature malleability
   - Mitigated by stateless design

### Defense in Depth

Each layer provides independent security guarantees:
- **Layer 1**: Protects against key compromise
- **Layer 2**: Prevents unauthorized access
- **Layer 3**: Blocks side-channel attacks
- **Layer 4**: Prevents replay and reuse attacks

## Implementation Guidelines

### Development Principles

1. **Never Trust Input**: All external data is validated
2. **Fail Securely**: Default to denying access on errors
3. **Minimize Attack Surface**: Remove unnecessary code/features
4. **Audit Everything**: Log all security-relevant events
5. **Update Regularly**: Keep PQC algorithms current

### Code Structure

```
sudarshan_engine/
├── sudarshan/           # Main package
│   ├── __init__.py      # Public API
│   ├── crypto/          # PQC implementations
│   ├── protocols/       # Box-in-a-Box layers
│   ├── format/          # .spq handling
│   └── utils/           # Helper functions
├── bindings/            # ctypes interfaces
├── docs/                # Documentation
├── tests/               # Test suites
└── examples/            # Usage examples
```

### Testing Strategy

- **Unit Tests**: Individual component testing
- **Integration Tests**: Layer interaction testing
- **Fuzzing**: Input validation testing
- **Performance Tests**: Cryptographic operation benchmarking
- **Security Tests**: Penetration testing and vulnerability assessment

## Deployment Considerations

### Environment Requirements

- **Hardware**: HSM/TPM/SGX support (optional but recommended)
- **Software**: Python 3.8+, liboqs, OpenSSL
- **Network**: Offline-first design, optional cloud connectivity

### Scalability

- **Horizontal**: Multiple engine instances
- **Vertical**: Hardware acceleration for crypto operations
- **Cloud**: Containerized deployment with orchestration

### Monitoring and Maintenance

- **Logging**: Comprehensive security event logging
- **Metrics**: Performance and security KPIs
- **Updates**: Automated PQC algorithm updates
- **Audits**: Regular security assessments

## Future Extensions

### Planned Features

- **Additional PQC Algorithms**: Support for new NIST standards
- **Hardware Acceleration**: GPU/FPGA acceleration for crypto
- **Distributed Operation**: Multi-party computation support
- **Regulatory Compliance**: FIPS 140-3, Common Criteria certification

### Research Directions

- **Zero-Knowledge Proofs**: Privacy-preserving operations
- **Homomorphic Encryption**: Computation on encrypted data
- **Threshold Cryptography**: Distributed key management
- **Post-Quantum ZKPs**: Privacy with quantum safety

This architecture provides a comprehensive foundation for quantum-safe cybersecurity, balancing security, usability, and future-proofing against emerging threats.