Common Encryption Techniques in Python: MD5, SHA‑256, Base64, AES, RSA, HMAC‑SHA256, Fernet, PBKDF2, Blowfish, XOR

1. MD5 Hashing

import hashlib
text = "Hello, World!"
md5_hash = hashlib.md5(text.encode()).hexdigest()
print(md5_hash)  # output: MD5 hash value
# Use case: quick message digest, not suitable for high‑security scenarios.

2. SHA‑256 Hashing

sha256_hash = hashlib.sha256(text.encode()).hexdigest()
print(sha256_hash)  # output: SHA‑256 hash value
# Use case: provides stronger security than MD5.

3. Base64 Encoding

import base64
encoded_text = base64.b64encode(text.encode('utf-8')).decode('utf-8')
print(encoded_text)  # output: Base64‑encoded text
# Use case: convert binary data to ASCII for transmission.

4. Base64 Decoding

decoded_text = base64.b64decode(encoded_text).decode('utf-8')
print(decoded_text)  # output: original text
# Use case: reverse of Base64 encoding.

5. AES Symmetric Encryption (CBC mode)

from Crypto.Cipher import AES
from Crypto.Util.Padding import pad
key = b'Sixteen byte key'
cipher = AES.new(key, AES.MODE_CBC)
ct_bytes = cipher.encrypt(pad(text.encode('utf-8'), AES.block_size))
iv = cipher.iv
print(base64.b64encode(iv + ct_bytes).decode('utf-8'))  # output: encrypted text
# Use case: efficient encryption of large data with a single shared key.

6. AES Decryption

from Crypto.Util.Padding import unpad
ct = base64.b64decode(ct_encoded)
iv = ct[:AES.block_size]
cipher = AES.new(key, AES.MODE_CBC, iv)
pt = unpad(cipher.decrypt(ct[AES.block_size:]), AES.block_size).decode('utf-8')
print(pt)  # output: original text
# Use case: paired with AES encryption.

7. RSA Asymmetric Encryption

from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
public_key = RSA.import_key(open('public.pem').read())
cipher_rsa = PKCS1_OAEP.new(public_key)
encrypted_data = cipher_rsa.encrypt(text.encode('utf-8'))
print(base64.b64encode(encrypted_data).decode('utf-8'))  # output: encrypted text
# Use case: encrypt small data or exchange symmetric keys.

8. RSA Decryption

private_key = RSA.import_key(open('private.pem').read())
cipher_rsa = PKCS1_OAEP.new(private_key)
decrypted_data = cipher_rsa.decrypt(base64.b64decode(encrypted_data)).decode('utf-8')
print(decrypted_data)  # output: original text
# Use case: paired with RSA encryption.

9. HMAC‑SHA256

hmac_sha256 = hmac.new(key, text.encode(), hashlib.sha256).hexdigest()
print(hmac_sha256)  # output: HMAC‑SHA256 hash value
# Use case: data integrity and authentication.

10. Fernet Symmetric Encryption

from cryptography.fernet import Fernet
key = Fernet.generate_key()
cipher_suite = Fernet(key)
cipher_text = cipher_suite.encrypt(text.encode('utf-8'))
print(cipher_text.decode())  # output: encrypted text
# Use case: simple, high‑level symmetric encryption for config files, etc.

11. Fernet Decryption

plain_text = cipher_suite.decrypt(cipher_text).decode('utf-8')
print(plain_text)  # output: original text
# Use case: paired with Fernet encryption.

12. PBKDF2 Password Hashing

salt = os.urandom(16)
hashed_password = hashlib.pbkdf2_hmac('sha256', b'password', salt, 100000)
print(salt + hashed_password)  # output: salt + hash
# Use case: securely store user passwords.

13. Blowfish Encryption

from Crypto.Cipher import Blowfish
bs = Blowfish.block_size
cipher = Blowfish.new(key, Blowfish.MODE_CBC)
plaintext = b'*' * bs  # pad to block size
msg = cipher.encrypt(plaintext)
print(msg)  # output: encrypted text
# Use case: older but still effective symmetric algorithm.

14. Blowfish Decryption

decrypted_msg = cipher.decrypt(msg)
print(decrypted_msg)  # output: original text
# Use case: paired with Blowfish encryption.

15. XOR Encryption

def xor_encrypt(input_str, key):
    return ''.join(chr(ord(x) ^ ord(y)) for (x, y) in zip(input_str, itertools.cycle(key)))

encrypted = xor_encrypt(text, 'secret')
print(encrypted)  # output: encrypted text
# Use case: simple demonstration, not for production.

16. XOR Decryption

decrypted = xor_encrypt(encrypted, 'secret')  # same key decrypts
print(decrypted)  # output: original text
# Use case: paired with XOR encryption.

Summary

These scripts demonstrate a variety of encryption techniques; choose the appropriate method based on security requirements. Some advanced algorithms require external libraries such as pycryptodome or cryptography, which can be installed via:
pip install pycryptodome cryptography
Always understand each algorithm's security properties and follow best practices to protect your data.