added aes-128 algorithm in ciphers

ciphers/aes_128.py

@@ -0,0 +1,77 @@
+import base64
+from Crypto.Cipher import AES
+from Crypto.Util.Padding import pad, unpad
+
+
+"""
+AES (Advanced Encryption Standard) is a symmetric encryption algorithm used
+    for secure data encryption. AES-128 uses a 128-bit key to encrypt and decrypt
+    data blocks of 128 bits. This implementation uses Cipher Block Chaining (CBC) mode
+    with PKCS7 padding for encrypting messages.
+
+    For more details, visit:
+    https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
+"""
+
+
+def aes_encrypt(plaintext: str, key: str) -> str:
+    """
+    AES-128 Encryption using CBC mode and PKCS7 padding.
+
+    :param plaintext: The plaintext message to be encrypted.
+    :param key: The encryption key (16 characters = 128 bits).
+    :return: Encrypted message (Base64 encoded).
+
+    >>> msg = "This is a secret message."
+    >>> key = "thisisaverysecret"
+    >>> enc = aes_encrypt(msg, key)
+    >>> dec = aes_decrypt(enc, key)
+    >>> aes_decrypt(enc, key) == msg
+    True
+    """
+    cipher = AES.new(key.encode("utf-8"), AES.MODE_CBC)
+    ciphertext = cipher.encrypt(pad(plaintext.encode("utf-8"), AES.block_size))
+    return base64.b64encode(cipher.iv + ciphertext).decode("utf-8")
+
+
+def aes_decrypt(ciphertext: str, key: str) -> str:
+    """
+    AES-128 Decryption using CBC mode and PKCS7 padding.
+
+    :param ciphertext: The Base64 encoded encrypted message.
+    :param key: The decryption key (16 characters = 128 bits).
+    :return: Decrypted plaintext message.
+
+    >>> msg = "This is a secret message."
+    >>> key = "thisisaverysecret"
+    >>> enc = aes_encrypt(msg, key)
+    >>> dec = aes_decrypt(enc, key)
+    >>> dec == msg
+    True
+    """
+    raw = base64.b64decode(ciphertext)
+    cipher = AES.new(key.encode("utf-8"), AES.MODE_CBC, iv=raw[: AES.block_size])
+    return unpad(cipher.decrypt(raw[AES.block_size :]), AES.block_size).decode("utf-8")
+
+
+def main() -> None:
+    key = input("Enter 16-character key (AES-128): ")
+    if len(key) != 16:
+        raise ValueError("Key must be 16 characters long!")
+
+    message = input("Enter message: ")
+
+    # Encryption
+    encrypted_message = aes_encrypt(message, key)
+    print("Encrypted message:", encrypted_message)
+
+    # Decryption
+    decrypted_message = aes_decrypt(encrypted_message, key)
+    print("Decrypted message:", decrypted_message)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
+    main()

requirements.txt

@@ -22,3 +22,5 @@ tweepy
 # yulewalker  # uncomment once audio_filters/equal_loudness_filter.py is fixed
 typing_extensions
 xgboost
+pycryptodome
+