Lab 7: AES - Advanced Encryption Standard

cd ~ && mkdir crypto-lab7 && cd crypto-lab7

# 1. AES dengan OpenSSL
echo "=== AES-256-CBC dengan OpenSSL ==*"
echo "Data rahasia: Password Bank = 123456" > /tmp/secret.txt

# Enkripsi
openssl enc -aes-256-cbc -salt -in /tmp/secret.txt -out /tmp/secret.enc -pass pass:"RahasiaBanget" -pbkdf2

# Dekripsi
openssl enc -d -aes-256-cbc -in /tmp/secret.enc -out /tmp/secret_dec.txt -pass pass:"RahasiaBanget" -pbkdf2

echo "Original:  $(cat /tmp/secret.txt)"
echo "Encrypted: $(xxd /tmp/secret.enc | head -3)"
echo "Decrypted: $(cat /tmp/secret_dec.txt)"
echo ""

# 2. AES dengan Python
python3 << 'PYEOF'
from Crypto.Cipher import AES
from Crypto.Random import get_random_bytes
import os

# Data
data = b"Ini adalah data rahasia yang sangat penting!"
key = get_random_bytes(32)  # AES-256

# ENKRIPSI (mode GCM - recommended)
cipher = AES.new(key, AES.MODE_GCM)
ciphertext, tag = cipher.encrypt_and_digest(data)
nonce = cipher.nonce

print(f"Key (hex):       {key.hex()}")
print(f"Nonce (hex):     {nonce.hex()}")
print(f"Ciphertext:      {ciphertext.hex()}")
print(f"Tag (auth):      {tag.hex()}")

# DEKRIPSI
cipher_dec = AES.new(key, AES.MODE_GCM, nonce=nonce)
plaintext = cipher_dec.decrypt_and_verify(ciphertext, tag)
print(f"Decrypted:       {plaintext.decode()}")
print()

# 3. AES modes comparison
print("=== AES Modes ==*")
print("ECB:   Sama plaintext → sama ciphertext ❌ (vulnerable)")
print("CBC:   Setiap blok tergantung blok sebelumnya ✅")
print("GCM:   CBC + authentication tag ✅✅ (recommended!)")
print("CTR:   Stream mode - bisa parallel processing")
PYEOF