8. Use of cryptographic algorithms in programming languages with Python

Implementation of Cryptographic Algorithms in Python

• Python is a popular programming language for implementing cryptographic algorithms due to its simplicity and rich libraries.
• Symmetric Encryption: Symmetric encryption algorithms such as AES and DES can be implemented in Python using libraries like pycryptodome.
• Asymmetric Encryption: Asymmetric encryption schemes like RSA can also be implemented using Python. The rsa library provides functionalities for RSA encryption and decryption.
• Hash Functions: Cryptographic hash functions like SHA-256 and SHA-3 are widely used for data integrity verification. Python's built-in hashlib library provides implementations of various hash functions.
• Digital Signatures: Digital signature algorithms such as RSA and ECDSA can be implemented in Python using libraries like pycryptodome and ecdsa.

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Laboratory Activities

Lab 1: Implementing AES Encryption in Python

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

def encrypt_AES(key, plaintext):
    cipher = AES.new(key, AES.MODE_ECB)
    ciphertext = cipher.encrypt(plaintext)
    return ciphertext

def decrypt_AES(key, ciphertext):
    cipher = AES.new(key, AES.MODE_ECB)
    plaintext = cipher.decrypt(ciphertext)
    return plaintext

# Example usage
key = get_random_bytes(16)
plaintext = b'Hello, world!'
ciphertext = encrypt_AES(key, plaintext)
decrypted_text = decrypt_AES(key, ciphertext)

print("Plaintext:", plaintext)
print("Ciphertext:", ciphertext)
print("Decrypted Text:", decrypted_text)

Lab 2: Implementing RSA Encryption in Python

from rsa import newkeys, encrypt, decrypt

def rsa_encryption(plaintext, public_key):
    return encrypt(plaintext, public_key)

def rsa_decryption(ciphertext, private_key):
    return decrypt(ciphertext, private_key)

# Example usage
public_key, private_key = newkeys(512)
plaintext = b'Hello, RSA!'
ciphertext = rsa_encryption(plaintext, public_key)
decrypted_text = rsa_decryption(ciphertext, private_key)

print("Plaintext:", plaintext)
print("Ciphertext:", ciphertext)
print("Decrypted Text:", decrypted_text)