Cybersecurity — Encryption

Symmetric encryption

from cryptography.fernet import Fernet

# Generate key
key = Fernet.generate_key()
cipher = Fernet(key)

# Encrypt
plaintext = b"secret message"
encrypted = cipher.encrypt(plaintext)

# Decrypt
decrypted = cipher.decrypt(encrypted)

AES encryption

from Crypto.Cipher import AES
from Crypto.Random import get_random_bytes

key = get_random_bytes(16)
cipher = AES.new(key, AES.MODE_EAX)
plaintext = b"secret data"
ciphertext, tag = cipher.encrypt_and_digest(plaintext)

Asymmetric encryption

from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import hashes

# Generate key pair
private_key = rsa.generate_private_key(public_exponent=65537, key_size=2048)
public_key = private_key.public_key()

# Encrypt
encrypted = public_key.encrypt(
    b"secret",
    padding.OAEP(mgf=padding.MGF1(algorithm=hashes.SHA256()), algorithm=hashes.SHA256(), label=None)
)

# Decrypt
decrypted = private_key.decrypt(
    encrypted,
    padding.OAEP(mgf=padding.MGF1(algorithm=hashes.SHA256()), algorithm=hashes.SHA256(), label=None)
)

Key management

1. Rotate keys regularly
2. Store keys securely
3. Use HSM for critical keys
4. Never hardcode keys

Best practices

1. Use strong algorithms
2. Implement proper key management
3. Encrypt at rest and in transit
4. Use appropriate encryption modes

Mini Practice

1. Implement symmetric encryption
2. Use asymmetric encryption
3. Set up key rotation
4. Test encryption/decryption

Up Next

Continue with Cryptography - Security algorithms.