I've recently started looking into encryption in python and I came across with pycryptodome library. I made this simple program that encrypt/decrypt a file using AES-GCM. Could someone take a look if I implemented the encryption and authentication correctly? For sake of simplicity, I'm posting only the encryption and makeKey functions.
import os import struct import secrets import hahslib from Cryptodome.Cipher import AES def makeKey(password, salt): key = hashlib.pbkdf2_hmac('sha512',password.encode('ascii'), salt, 1000000) return key[:32] def encrypt(password, inputFileName): #creates the needed variables for encryption salt = secrets.token_bytes(16) key = makeKey(password, salt) nonce = secrets.token_bytes(AES.block_size) cipher = AES.new(key, AES.MODE_GCM, nonce=nonce) #put the file size, salt and nonce in outputfile fileSize = os.path.getsize(inputFileName) with open("output", "wb") as outputFile: outputFile.write(struct.pack('<Q', fileSize)) outputFile.write(salt) outputFile.write(nonce) #beginning of encryption itself chunkSize = 64 * 1024 with open(inputFileName, "rb") as inputFile: while True: chunk = inputFile.read(chunkSize) if len(chunk) == 0: outputFile.write(cipher.digest()) break outputFile.write(cipher.encrypt(chunk))