Encrypt a file with AES 256 EAX

aes.py

import binascii
import json
from base64 import b64encode, b64decode

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

data = b"..."

header = b"storachaProof"
aes_key = get_random_bytes(32)
print(f"This is our key in hex: {aes_key.hex()}")

cipher = AES.new(aes_key, AES.MODE_EAX)
cipher.update(header)
ciphertext, tag = cipher.encrypt_and_digest(data)

json_k = ["nonce", "header", "ciphertext", "tag"]
json_v = [b64encode(x).decode() for x in (cipher.nonce, header, ciphertext, tag)]
payload = dict(zip(json_k, json_v))

with open("encrypted_proof.bin", "w") as fp:
    json.dump(payload, fp, indent=4)

#### Reading check

# load the hex value
aes_key = binascii.unhexlify("...")

with open("encrypted_proof.bin", "r") as fp:
    payload = json.load(fp)

payload = {k: b64decode(v) for k, v in payload.items()}

cipher = AES.new(aes_key, AES.MODE_EAX, nonce=payload["nonce"])
cipher.update(payload["header"])
plaintext = cipher.decrypt(payload["ciphertext"])

try:
    cipher.verify(payload["tag"])
    print(f"The message is authentic:\n{plaintext}")
except ValueError:
    print("Key incorrect or message corrupted")