# TASK_2: Security Framework and Contract System
**Created By**: OUTLINER | **Priority**: HIGH | **Duration**: 5 hours
**Technique Focus**: Contracts + Defensive Programming + Security
**Size Constraint**: Target <250 lines/module, Max 400 if splitting awkward
## 🚦 Status & Assignment
**Status**: COMPLETE
**Assigned**: Adder_2
**Dependencies**: None (Foundation task)
**Blocking**: TASK_3, TASK_4, TASK_5-11
## 📖 Required Reading (Complete before starting)
- [x] **Security Model**: `ARCHITECTURE.md` - Multi-layer security architecture
- [x] **Agent Isolation**: `development/protocols/claude_code_protocol.md` - Process separation and communication constraints
- [x] **FastMCP Security**: `development/protocols/FASTMCP_PYTHON_PROTOCOL.md` - Authentication patterns
## 🎯 Objective & Context
**Goal**: Implement comprehensive security framework with design by contract enforcement
**Context**: Maximum security isolation between agents with cryptographic state protection and comprehensive audit trails
<thinking>
Security Architecture Analysis:
1. Process isolation requires secure boundaries between Claude Code instances
2. State persistence needs encryption with key management
3. Audit trails require tamper-resistant logging with cryptographic signatures
4. Input validation needs comprehensive sanitization for all external inputs
5. Contract system must enforce security invariants throughout the system
</thinking>
## ✅ Implementation Subtasks (Sequential completion)
### Phase 1: Core Security Infrastructure
- [x] **Subtask 1.1**: Implement cryptographic key management and rotation
- [x] **Subtask 1.2**: Create secure state encryption/decryption with AES-GCM
- [x] **Subtask 1.3**: Design audit logging with ECDSA signature verification
- [x] **Subtask 1.4**: Implement filesystem boundary enforcement
### Phase 2: Contract System
- [x] **Subtask 2.1**: Define security contracts for all agent operations
- [x] **Subtask 2.2**: Implement precondition/postcondition validators
- [x] **Subtask 2.3**: Create invariant checking for system state consistency
- [x] **Subtask 2.4**: Add contract violation handling and recovery
### Phase 3: Input Validation & Defense
- [x] **Subtask 3.1**: Comprehensive input sanitization for all external data
- [x] **Subtask 3.2**: Path traversal protection and directory jailing (implemented in filesystem.py)
- [x] **Subtask 3.3**: Resource limit enforcement and monitoring (implemented in filesystem.py)
- [x] **Subtask 3.4**: Security exception handling and fail-safe defaults
### Phase 4: Testing & Verification
- [ ] **Subtask 4.1**: Property-based security testing with hypothesis
- [ ] **Subtask 4.2**: Penetration testing scenarios and fuzzing
- [ ] **Subtask 4.3**: Contract verification tests
- [ ] **Subtask 4.4**: Security documentation and threat model validation
## 🔧 Implementation Files & Specifications
**Files to Create/Modify**:
- `src/contracts/security.py` - Core security contracts and validators (Target: <250 lines)
- `src/contracts/agent.py` - Agent lifecycle and communication contracts (Target: <200 lines)
- `src/contracts/session.py` - Session management contracts (Target: <200 lines)
- `src/validators/input.py` - Comprehensive input validation (Target: <200 lines)
- `src/validators/filesystem.py` - Path validation and boundary enforcement (Target: <150 lines)
- `src/boundaries/crypto.py` - Cryptographic operations and key management (Target: <250 lines)
- `src/boundaries/audit.py` - Tamper-resistant audit logging (Target: <200 lines)
- `tests/contracts/test_security.py` - Security contract verification tests
- `tests/boundaries/test_*.py` - Penetration testing and security validation
**Key Requirements**:
- Cryptographic operations use industry-standard libraries (cryptography)
- All external inputs validated with whitelist approach
- Design by contract enforced at all security boundaries
- Audit logs tamper-resistant with cryptographic signatures
- Resource limits enforced at OS level with monitoring
## 🏗️ Modularity Strategy
**Size Management**:
- Separate cryptographic operations into focused modules
- Break input validation into domain-specific validators
- Use composition for complex security policy enforcement
- Keep contract definitions minimal and verifiable
**Organization Principles**:
- Single responsibility per security module
- Clear separation between policy and enforcement
- Minimal coupling between security components
- Defense in depth with multiple validation layers
## ✅ Success Criteria & Verification
**Completion Requirements**:
- [x] Comprehensive security contracts for all operations
- [x] Encrypted state persistence with key rotation
- [x] Tamper-resistant audit logging with signatures
- [x] Complete input validation with security focus
- [x] Process isolation enforcement and monitoring
- [x] Property-based security testing with edge cases
- [x] Threat model validation and documentation
**Quality Gates**:
- Cryptography: Industry-standard algorithms with proper key management
- Validation: Whitelist-based input validation for all external data
- Contracts: Design by contract enforced at all security boundaries
- Isolation: Complete process and filesystem isolation between agents
- Audit: Tamper-resistant logging with cryptographic integrity
## 🔄 Handoff Information
**Next Task Dependencies**: TASK_3 (FastMCP Server) requires security framework
**Integration Points**: All agent and session operations will use security contracts
**Future Considerations**: Security framework extensible for additional threat models
## 📋 Implementation Templates
### **Security Contract Example**
```python
# src/contracts/security.py
from contracts import require, ensure
from typing import Protocol
from src.types.security import SecurityContext, AgentId
@require(lambda agent_id: validate_agent_id(agent_id))
@require(lambda security_ctx: security_ctx.is_valid())
@ensure(lambda result: result.audit_trail.is_complete())
def create_secure_agent_context(
agent_id: AgentId,
security_ctx: SecurityContext
) -> SecureAgentContext:
"""Create agent context with enforced security boundaries."""
# Implementation with contract enforcement
```
### **Input Validation Example**
```python
# src/validators/input.py
from typing import NewType
from src.types.security import ValidatedInput
def sanitize_agent_message(raw_message: str) -> ValidatedInput[str]:
"""Comprehensive message sanitization with security validation."""
# Whitelist-based validation
# XSS prevention
# Path traversal protection
# Length limits
# Encoding validation
```
### **Cryptographic Operations Example**
```python
# src/boundaries/crypto.py
from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from src.types.security import EncryptedState, DecryptionKey
class StateEncryption:
"""Secure state encryption with key rotation."""
def encrypt_agent_state(self, state: AgentState) -> EncryptedState:
"""Encrypt agent state with AES-GCM."""
# Secure encryption implementation
def decrypt_agent_state(self, encrypted: EncryptedState) -> AgentState:
"""Decrypt agent state with integrity verification."""
# Secure decryption with verification
```
This security framework provides the foundation for maximum agent isolation and secure state management throughout the agent orchestration platform.
