Security Guidelines

Security Overview

Cryptographic security extends far beyond the mathematical correctness of algorithms. This guide covers essential security practices for implementing robust cryptographic systems using Forge EC.

Security Principles

• Defense in Depth: Multiple layers of security protection
• Least Privilege: Minimal access rights for components
• Fail Securely: Secure defaults and safe failure modes
• Complete Mediation: All access attempts must be checked
• Open Design: Security through design, not obscurity

Key Management

Proper key management is crucial for maintaining cryptographic security. Keys must be generated, stored, used, and destroyed securely.

Secure Key Generation

use forge_ec::signatures::ecdsa::PrivateKey;
use forge_ec::curves::secp256k1::Secp256k1;
use forge_ec::rng::SecureRng;

// ✅ CORRECT: Use cryptographically secure RNG
let mut rng = SecureRng::new();
let private_key = PrivateKey::::generate(&mut rng);

// ❌ WRONG: Never use predictable sources
// let weak_key = PrivateKey::from_bytes(&[1, 2, 3, ...]);

// ✅ CORRECT: Generate multiple keys independently
let key1 = PrivateKey::::generate(&mut rng);
let key2 = PrivateKey::::generate(&mut rng);

// Verify keys are different
assert_ne!(key1.to_bytes(), key2.to_bytes());

Secure Key Storage

use forge_ec::signatures::ecdsa::PrivateKey;
use forge_ec::secure_memory::SecureBytes;
use zeroize::Zeroize;

// ✅ CORRECT: Use secure memory for sensitive data
let mut key_material = SecureBytes::new(32);
// ... populate key_material securely ...

let private_key = PrivateKey::from_secure_bytes(&key_material)?;

// ✅ CORRECT: Explicitly clear sensitive data
key_material.zeroize();

// ✅ CORRECT: Use RAII for automatic cleanup
{
    let private_key = PrivateKey::generate(&mut rng);
    // Use private_key...
    // Automatically zeroized when dropped
}

// ❌ WRONG: Leaving sensitive data in memory
// let key_hex = private_key.to_hex(); // Leaves copy in memory
// println!("Key: {}", key_hex); // Logs sensitive data

Random Number Generation

Cryptographic security depends heavily on high-quality randomness. Poor random number generation is one of the most common causes of cryptographic failures.

Entropy Sources

use forge_ec::rng::{SecureRng, EntropySource};

// ✅ CORRECT: Use system entropy sources
let mut rng = SecureRng::from_entropy();

// ✅ CORRECT: Seed with additional entropy if available
let mut rng = SecureRng::new();
rng.add_entropy(&additional_entropy_bytes);

// ✅ CORRECT: Check entropy quality
if rng.entropy_estimate() < 256 {
    return Err("Insufficient entropy");
}

// ❌ WRONG: Using predictable seeds
// let mut rng = SecureRng::from_seed([0u8; 32]);

// ❌ WRONG: Using standard library RNG for crypto
// use std::collections::hash_map::DefaultHasher;
// let weak_rng = DefaultHasher::new();

Timing Attack Prevention

Timing attacks exploit variations in execution time to extract sensitive information. Forge EC implements constant-time operations to prevent these attacks.

Constant-Time Operations

use forge_ec::constant_time::ConstantTimeEq;

// ✅ CORRECT: Use constant-time comparison
fn verify_signature_safe(
    signature1: &[u8], 
    signature2: &[u8]
) -> bool {
    signature1.ct_eq(signature2).into()
}

// ❌ WRONG: Variable-time comparison
fn verify_signature_unsafe(
    signature1: &[u8], 
    signature2: &[u8]
) -> bool {
    signature1 == signature2 // Leaks timing information!
}

// ✅ CORRECT: All Forge EC operations are constant-time
let is_valid = public_key.verify(message, &signature)?;

// The verification time is independent of:
// - The message content
// - The signature values  
// - Whether the signature is valid or invalid

Side-Channel Protection

Side-channel attacks exploit information leaked through physical implementation characteristics. Forge EC includes protections against common side-channel attacks.

Power Analysis Protection

Common Pitfalls

Learn from common mistakes that can compromise cryptographic security:

Nonce Reuse

Weak Random Number Generation

Improper Key Storage

Best Practices

Follow these best practices for secure cryptographic implementations:

Development Guidelines

• Code Reviews: Have cryptographic code reviewed by security experts
• Testing: Implement comprehensive unit and integration tests
• Auditing: Regular security audits of cryptographic implementations
• Updates: Keep cryptographic libraries up to date
• Documentation: Document security assumptions and threat models

Operational Security

• Key Rotation: Implement regular key rotation policies
• Access Control: Limit access to cryptographic keys and operations
• Monitoring: Monitor for unusual cryptographic operations
• Incident Response: Have procedures for cryptographic compromises
• Backup & Recovery: Secure backup and recovery procedures for keys

Compliance Considerations