# AES 256 Encryption/Decryption Using pycryptodome Library

# Imports

import hashlib

from base64 import b64encode, b64decode

import os

from Cryptodome.Cipher import AES

from Cryptodome.Random import get_random_bytes

import platform

# For different OS

if platform.system() == "Windows":

os.system("cls")

else:

os.system("clear")

# Start of Encryption Function

def encrypt(plain_text, password):

# generate a random salt

salt = get_random_bytes(AES.block_size)

# use the Scrypt KDF to get a private key from the password

private_key = hashlib.scrypt(

password.encode(), salt=salt, n=2**14, r=8, p=1, dklen=32

)

# create cipher config

cipher_config = AES.new(private_key, AES.MODE_GCM)

# return a dictionary with the encrypted text

cipher_text, tag = cipher_config.encrypt_and_digest(bytes(plain_text, "utf-8"))

return {

"cipher_text": b64encode(cipher_text).decode("utf-8"),

"salt": b64encode(salt).decode("utf-8"),

"nonce": b64encode(cipher_config.nonce).decode("utf-8"),

"tag": b64encode(tag).decode("utf-8"),

}

# Start of Decryption Function

def decrypt(enc_dict, password):

# decode the dictionary entries from base64

salt = b64decode(enc_dict["salt"])

cipher_text = b64decode(enc_dict["cipher_text"])

nonce = b64decode(enc_dict["nonce"])

tag = b64decode(enc_dict["tag"])

# generate the private key from the password and salt

private_key = hashlib.scrypt(

password.encode(), salt=salt, n=2**14, r=8, p=1, dklen=32

)

# create the cipher config

cipher = AES.new(private_key, AES.MODE_GCM, nonce=nonce)

# decrypt the cipher text

decrypted = cipher.decrypt_and_verify(cipher_text, tag)

return decrypted

def main():

print("\t\tAES 256 Encryption and Decryption Algorithm")

print("\t\t-------------------------------------------\n\n")

x = input("Enter 1 to encrypt and 2 to decrypt :")

if x == 1:

password = input("Enter the Password: ")

secret_mssg = input("\nEnter the Secret Message: ")

# First let us encrypt secret message

encrypted = encrypt(secret_mssg, password)

print("\n\nEncrypted:")

print("---------------\n")

print("\n".join("{}: {}".format(k, v) for k, v in encrypted.items()))

# Now let us decrypt the message using our original password

if x == 2:

encrypted = input("Enter the encrypted message")

password = input("Enter the password")

decrypted = decrypt(encrypted, password)

print("\n\nDecrypted:")

print("-----------------\n")

print(bytes.decode(decrypted))

main()