Lexecon is a cryptographic governance system designed with security as a core principle. We take the security of Lexecon and the systems that depend on it very seriously.

• Supported Versions
• Reporting a Vulnerability
• Security Features
• Threat Model
• Security Best Practices
• Cryptographic Standards
• Known Security Considerations
• Security Audit History
• Security Updates
• Security Hall of Fame

We provide security updates for the following versions:

Note: As Lexecon is currently in alpha (v0.1.x), we recommend thorough security testing before production use.

• Current Version: Always receives security updates
• Previous Major Version: Receives critical security updates for 6 months after new major release
• Older Versions: No longer supported, users should upgrade

DO NOT open public issues for security vulnerabilities.

1. Email Security Team

   • Email: security@lexicoding.systems
   • PGP Key: Available here
   • Subject: "[SECURITY] Brief description"

2. Include in Your Report

   • Description of the vulnerability
   • Steps to reproduce
   • Potential impact
   • Suggested fix (if you have one)
   • Your contact information

3. What to Expect

   • < 48 hours: Initial response acknowledging receipt
   • < 7 days: Preliminary assessment and severity classification
   • < 30 days: Fix developed and tested (for critical issues)
   • Coordinated disclosure: We'll work with you on disclosure timing

## Vulnerability Description
Brief description of the vulnerability

## Affected Components
- Component: [e.g., Policy Engine, Ledger, API]
- Version: [e.g., 0.1.0]

## Steps to Reproduce
1. Step one
2. Step two
3. Step three

## Proof of Concept
Code or commands demonstrating the vulnerability

## Impact Assessment
- Confidentiality: [None/Low/Medium/High/Critical]
- Integrity: [None/Low/Medium/High/Critical]
- Availability: [None/Low/Medium/High/Critical]

## Suggested Mitigation
Your suggestions for fixing the vulnerability

## Additional Context
Any other relevant information

We use the following severity levels:

We request:

• 90 days for non-critical vulnerabilities
• Immediate coordination for actively exploited vulnerabilities
• Credit will be given in release notes (if desired)

Lexecon implements multiple layers of security:

• All decisions are signed using Ed25519 (256-bit security)
• Signatures are verified before trust
• Key rotation supported

• Ledger entries are cryptographically linked
• Any tampering is immediately detectable
• Uses SHA-256 for hashing

• Time-limited authorization tokens
• Scope-restricted permissions
• Cryptographically signed
• Cannot be forged without private key

• Unknown actions are rejected by default in strict mode
• Explicit permissions required
• Fail-safe behavior on errors

• All inputs are validated and sanitized
• Type checking with Pydantic models
• SQL injection prevention (parameterized queries)
• XSS prevention (output encoding)

• API endpoints are rate-limited
• Prevents brute-force attacks
• Configurable limits per endpoint

• All decisions recorded in tamper-evident ledger
• Full traceability of actions
• Integrity verification available

1. Cryptographic Keys: Ed25519 signing keys for nodes
2. Policy Definitions: Governance policies
3. Audit Ledger: Historical decision records
4. Capability Tokens: Authorization tokens
5. Decision Integrity: Correctness of governance decisions

• Goal: Bypass governance, exfiltrate data, disrupt service
• Capabilities: Network access, crafted requests
• Mitigations: Input validation, rate limiting, authentication

• Goal: Bypass policy restrictions, escalate privileges
• Capabilities: Crafted tool call requests, prompt injection
• Mitigations: Structured evaluation, policy enforcement, ledger

• Goal: Manipulate policies, tamper with ledger
• Mitigations: Policy versioning, hash chaining, audit trails

Attack: Craft requests to circumvent policy restrictions Mitigations:

• Strict input validation
• Structured policy evaluation
• Deny-by-default mode
• Comprehensive testing

Attack: Inject malicious instructions to manipulate model behavior Mitigations:

• Structured decision requests (JSON)
• Separate evaluation context
• Policy-based rather than prompt-based control

Attack: Create fake capability tokens Mitigations:

• Cryptographic signatures (Ed25519)
• Token verification on every use
• Time-limited tokens
• Policy version binding

Attack: Modify historical records Mitigations:

• Hash chaining
• Cryptographic signatures
• Periodic integrity verification
• Immutable append-only structure

Attack: Overwhelm system with requests Mitigations:

• Rate limiting
• Request timeouts
• Resource limits
• Monitoring and alerting

Attack: Steal or leak signing keys Mitigations:

• Filesystem permissions
• Key rotation support
• KMS integration (recommended for production)
• Separate keys per node

Development:

# Keys stored in node directory with restricted permissions
chmod 600 ~/.lexecon/nodes/*/keys/private_key.pem

Production:

# Use a Key Management Service (KMS)
# Examples: AWS KMS, Azure Key Vault, HashiCorp Vault
export LEXECON_KMS_PROVIDER=aws
export LEXECON_KMS_KEY_ID=arn:aws:kms:...

Key Rotation:

# Rotate keys periodically (every 90 days recommended)
lexecon identity rotate-key --node-id production-node

Always use TLS for API communication:

# config.yaml
server:
  tls:
    enabled: true
    cert_file: /path/to/cert.pem
    key_file: /path/to/key.pem

Restrict network access:

# Use firewall rules
iptables -A INPUT -p tcp --dport 8000 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8000 -j DROP

Restrict file system access:

# Node directories should be owned by service user
chown -R lexecon:lexecon ~/.lexecon/
chmod 700 ~/.lexecon/nodes/

Use dedicated service accounts:

# Don't run as root
sudo -u lexecon lexecon server --node-id prod

Set up security monitoring:

# config.yaml
monitoring:
  alert_on_denied_high_risk: true
  alert_on_policy_changes: true
  alert_on_ledger_verification_failures: true

Monitor logs for suspicious activity:

# Watch for repeated denials
tail -f /var/log/lexecon/decisions.log | grep "allowed: false"

# Alert on policy modifications
tail -f /var/log/lexecon/audit.log | grep "policy_loaded"

Input Validation:

# Always validate and sanitize inputs
from pydantic import BaseModel, validator

class DecisionRequest(BaseModel):
    actor: str
    risk_level: int

    @validator('risk_level')
    def validate_risk_level(cls, v):
        if v < 1 or v > 5:
            raise ValueError('Risk level must be between 1 and 5')
        return v

Avoid Secrets in Code:

# Bad
api_key = "sk-1234567890abcdef"

# Good
import os
api_key = os.environ.get('API_KEY')
if not api_key:
    raise ValueError("API_KEY environment variable not set")

Use Parameterized Queries:

# Bad (SQL injection risk)
cursor.execute(f"SELECT * FROM ledger WHERE id = '{entry_id}'")

# Good
cursor.execute("SELECT * FROM ledger WHERE id = ?", (entry_id,))

Regular updates:

# Check for vulnerable dependencies
pip install safety
safety check

# Update dependencies
pip install --upgrade -r requirements.txt

Pin dependencies:

# requirements.txt - use specific versions
cryptography==42.0.5
fastapi==0.109.2
pydantic==2.5.3

• Fast: Faster than RSA and ECDSA
• Small keys: 32-byte public keys
• Deterministic: No need for random number generation during signing
• Widely supported: Available in cryptography.io
• Secure: Resistant to timing attacks

1. Signature Integrity: Cannot forge signatures without private key
2. Hash Collision Resistance: SHA-256 provides 128-bit collision resistance
3. Deterministic Serialization: Same data always produces same hash
4. Non-repudiation: Signatures prove origin

• Issue: Keys stored on filesystem by default
• Risk: Keys could be compromised if system is breached
• Mitigation: Use KMS in production (planned for v0.3.0)
• Workaround: Restrict filesystem permissions, use disk encryption

• Issue: API doesn't have built-in rate limiting
• Risk: DoS attacks possible
• Mitigation: Use reverse proxy (nginx, API gateway)
• Planned: Built-in rate limiting in v0.2.0

• Issue: No distributed consensus
• Risk: Single point of failure
• Mitigation: High availability setup, regular backups
• Planned: Multi-node federation in v0.3.0

Lexecon's security model assumes:

1. Trusted Execution Environment: Node runs in secure environment
2. Secure Transport: TLS used for all network communication
3. Key Security: Private keys are kept secure
4. System Security: Underlying OS is secure and patched
5. Network Security: Network is protected by firewall

If these assumptions don't hold, security guarantees may not apply.

• 2025-12: Initial security design review
• Ongoing code reviews with security focus

We plan to launch a bug bounty program once we reach v1.0.0.

Subscribe to security updates:

• GitHub: Watch repository → Custom → Security alerts
• Email: security-announce@lexicoding.systems
• RSS: https://lexicoding.systems/security.xml

# Check current version
lexecon --version

# Update to latest version
pip install --upgrade lexecon

# Verify update
lexecon --version

# Test in staging first
lexecon doctor --check-all

1. Security fix developed in private repository
2. Fix tested thoroughly
3. Advisory drafted
4. Release published
5. Advisory published
6. Notification sent to subscribers

We recognize security researchers who help make Lexecon more secure:

Want to be listed? Report a valid security vulnerability!

• Email: security@lexicoding.systems
• PGP Key: https://lexicoding.systems/pgp-key.txt
• Response Time: < 48 hours

For non-sensitive security questions:

• GitHub Discussions: https://github.com/Lexicoding-systems/Lexecon/discussions
• Documentation: https://lexecon.readthedocs.io/security

Lexecon is designed to help with:

• GDPR: Article 25 (Privacy by Design)
• EU AI Act: Annex IV (Technical Documentation)
• SOC 2: CC6.1 (Logical and Physical Access Controls)
• NIST Cybersecurity Framework: Identify, Protect, Detect

• SOC 2 Type II (planned for v1.0.0)
• ISO 27001 (under consideration)

• OWASP Top 10
• CWE Top 25
• NIST Cryptographic Standards

# Dependency scanning
pip install safety
safety check

# Static analysis
pip install bandit
bandit -r src/

# Secret scanning
pip install detect-secrets
detect-secrets scan

# License compliance
pip install pip-licenses
pip-licenses

We thank the security research community for their valuable contributions to making Lexecon more secure.

Report security issues responsibly. We appreciate your efforts to keep Lexecon and its users safe.

Last Updated: 2025-12-31