Aes cbc 128 192 and 256 encryption decryption in python 3 using pkcs7 padding

When it comes to encryption and decryption in Python 3, there are several options available. In this article, we will explore three different ways to perform AES CBC encryption and decryption using PKCS7 padding with key sizes of 128, 192, and 256 bits.

Option 1: Using the PyCryptodome Library

The PyCryptodome library is a powerful and widely used library for cryptographic operations in Python. It provides a high-level interface for AES encryption and decryption.

from Crypto.Cipher import AES
from Crypto.Util.Padding import pad, unpad

def aes_cbc_encrypt(key, data):
    cipher = AES.new(key, AES.MODE_CBC)
    ciphertext = cipher.encrypt(pad(data, AES.block_size))
    return ciphertext

def aes_cbc_decrypt(key, ciphertext):
    cipher = AES.new(key, AES.MODE_CBC)
    data = unpad(cipher.decrypt(ciphertext), AES.block_size)
    return data

# Example usage
key = b'secretkey128bit'
data = b'Hello, World!'
ciphertext = aes_cbc_encrypt(key, data)
decrypted_data = aes_cbc_decrypt(key, ciphertext)
print(decrypted_data)

In this code snippet, we import the necessary modules from the PyCryptodome library. The aes_cbc_encrypt function takes a key and data as input, creates an AES cipher object in CBC mode, encrypts the data with PKCS7 padding, and returns the ciphertext. The aes_cbc_decrypt function takes a key and ciphertext as input, creates an AES cipher object in CBC mode, decrypts the ciphertext, removes the padding, and returns the decrypted data.

Option 2: Using the cryptography Library

The cryptography library is another popular choice for cryptographic operations in Python. It provides a high-level interface for AES encryption and decryption.

from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import padding

def aes_cbc_encrypt(key, data):
    padder = padding.PKCS7(128).padder()
    padded_data = padder.update(data) + padder.finalize()
    cipher = Cipher(algorithms.AES(key), modes.CBC(key))
    encryptor = cipher.encryptor()
    ciphertext = encryptor.update(padded_data) + encryptor.finalize()
    return ciphertext

def aes_cbc_decrypt(key, ciphertext):
    cipher = Cipher(algorithms.AES(key), modes.CBC(key))
    decryptor = cipher.decryptor()
    decrypted_data = decryptor.update(ciphertext) + decryptor.finalize()
    unpadder = padding.PKCS7(128).unpadder()
    data = unpadder.update(decrypted_data) + unpadder.finalize()
    return data

# Example usage
key = b'secretkey128bit'
data = b'Hello, World!'
ciphertext = aes_cbc_encrypt(key, data)
decrypted_data = aes_cbc_decrypt(key, ciphertext)
print(decrypted_data)

In this code snippet, we import the necessary modules from the cryptography library. The aes_cbc_encrypt function takes a key and data as input, pads the data with PKCS7 padding, creates an AES cipher object in CBC mode, encrypts the padded data, and returns the ciphertext. The aes_cbc_decrypt function takes a key and ciphertext as input, creates an AES cipher object in CBC mode, decrypts the ciphertext, removes the padding, and returns the decrypted data.

Option 3: Using the pycrypto Library

The pycrypto library is another option for performing AES CBC encryption and decryption in Python. It provides a low-level interface for cryptographic operations.

from Crypto.Cipher import AES
from Crypto.Util.Padding import pad, unpad

def aes_cbc_encrypt(key, data):
    cipher = AES.new(key, AES.MODE_CBC)
    ciphertext = cipher.encrypt(pad(data, AES.block_size))
    return ciphertext

def aes_cbc_decrypt(key, ciphertext):
    cipher = AES.new(key, AES.MODE_CBC)
    data = unpad(cipher.decrypt(ciphertext), AES.block_size)
    return data

# Example usage
key = b'secretkey128bit'
data = b'Hello, World!'
ciphertext = aes_cbc_encrypt(key, data)
decrypted_data = aes_cbc_decrypt(key, ciphertext)
print(decrypted_data)

In this code snippet, we import the necessary modules from the pycrypto library. The aes_cbc_encrypt function takes a key and data as input, creates an AES cipher object in CBC mode, encrypts the data with PKCS7 padding, and returns the ciphertext. The aes_cbc_decrypt function takes a key and ciphertext as input, creates an AES cipher object in CBC mode, decrypts the ciphertext, removes the padding, and returns the decrypted data.

After exploring these three options, it is clear that the PyCryptodome library (Option 1) provides a more user-friendly and high-level interface for AES CBC encryption and decryption. It abstracts away many of the low-level details and provides convenient functions for padding and unpadding the data. Therefore, Option 1 is the recommended choice for performing AES CBC encryption and decryption in Python 3 using PKCS7 padding.

Rate this post

11 Responses

    1. Sorry, but I have to disagree. Option 2 may have its strengths, but its not the be-all and end-all. Each library has its own merits, and it ultimately depends on the specific use case. Lets not dismiss the others so easily.

    1. Ive tried both options, and honestly, Option 1 is way more intuitive and user-friendly. Option 2 has a steeper learning curve, and I found it quite frustrating to navigate. But hey, different strokes for different folks! Give them both a shot and see what works best for you.

Leave a Reply

Your email address will not be published. Required fields are marked *

Table of Contents