chapter19.md

Chapter 19: Cryptography and Security Modules

Securing data is a fundamental requirement for modern applications. NAAb provides a crypto module that offers essential cryptographic primitives, allowing you to hash data, generate secure random numbers, and perform basic encryption.

19.1 Hashing with the crypto Module

Hashing functions transform data into a fixed-size string of characters, which is typically a digest that represents the data. The crypto module supports common algorithms like MD5, SHA-1, SHA-256, and SHA-512.

use crypto

main {
    let data = "secret_password"

    // SHA-256 Hash
    let hash = crypto.sha256(data)
    print("SHA-256:", hash)

    // SHA-512 Hash
    let hash512 = crypto.sha512(data)
    print("SHA-512:", hash512)
    
    // MD5 (Legacy, not recommended for security)
    print("MD5:", crypto.md5(data))
}

19.2 Secure Randomness

For generating cryptographic keys, tokens, or salts, you should use a cryptographically secure random number generator (CSPRNG), not the standard math random functions.

main {
    // Generate random bytes (hex encoded)
    let random_hex = crypto.random_bytes(16)
    print("Random Token:", random_hex)
}

19.3 Encryption

For encryption and decryption, use a polyglot block with a mature library. The crypto module currently focuses on hashing and randomness:

main {
    let plaintext = "Sensitive Data"
    let key = "my_secret_key_32bytes_long_12345"

    let encrypted = <<python[plaintext, key]
from cryptography.fernet import Fernet
import base64, hashlib
key_bytes = base64.urlsafe_b64encode(hashlib.sha256(key.encode()).digest())
f = Fernet(key_bytes)
f.encrypt(plaintext.encode()).decode()
>>

    print("Encrypted:", encrypted)
}

Security Note: Always manage encryption keys securely. Avoid hardcoding keys in your source code. Use environment variables (see Chapter 9) or a dedicated secrets management solution.