Hashing and Encryption in Python

What is Hashing?

Hashing is a one-way function that converts input data into a fixed-length string (hash). Hash functions are used for password storage, data integrity, and digital signatures.

Common Hashing Algorithms:

MD5 (Not Secure)
SHA-1 (Weak Security)
SHA-256, SHA-512 (Recommended)

Hashing in Python (SHA-256 Example)

import hashlib

def hash_text(text):
    hash_obj = hashlib.sha256(text.encode())
    return hash_obj.hexdigest()

# Example usage
print(hash_text("password123"))

SHA-256 generates a unique hash that cannot be reversed.

What is Encryption?

Encryption converts plaintext into ciphertext using a key. Unlike hashing, encryption is reversible using a decryption key.

Common Encryption Algorithms:

Symmetric Encryption (AES, DES) – Same key for encryption & decryption.
Asymmetric Encryption (RSA, ECC) – Public key encrypts, private key decrypts.

AES Encryption with Python (Symmetric Encryption)

from Crypto.Cipher import AES
import base64

key = b'1234567890abcdef'  # 16-byte key
cipher = AES.new(key, AES.MODE_EAX)

def encrypt_text(plain_text):
    nonce = cipher.nonce
    ciphertext, tag = cipher.encrypt_and_digest(plain_text.encode())
    return base64.b64encode(nonce + ciphertext).decode()

# Example usage
encrypted = encrypt_text("Hello, Secure World!")
print("Encrypted:", encrypted)

AES encryption ensures secure data transmission.

RSA Encryption (Asymmetric Encryption)

from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
import base64

# Generate RSA Keys
key = RSA.generate(2048)
public_key = key.publickey().export_key()
private_key = key.export_key()

def rsa_encrypt(plain_text, pub_key):
    recipient_key = RSA.import_key(pub_key)
    cipher_rsa = PKCS1_OAEP.new(recipient_key)
    encrypted = cipher_rsa.encrypt(plain_text.encode())
    return base64.b64encode(encrypted).decode()

# Example usage
encrypted_message = rsa_encrypt("Secure Data!", public_key)
print("Encrypted:", encrypted_message)

RSA allows secure communication between parties.

When to Use Hashing vs Encryption?

Use Case	Hashing	Encryption
Password Storage	Yes	No
Data Integrity (Checksums)	Yes	No
Secure Data Transfer	No	Yes
Digital Signatures	Yes	Yes