Secure Encryption for Password-Protected Strings
Problem:
Python lacks a built-in mechanism to encrypt and decrypt strings using a password. This can be problematic for scenarios requiring data obfuscation without strong security measures.
Solution:
Cryptography libraries, such as cryptography, provide secure encryption schemes.
Using Fernet for Symmetric Key Encryption
Fernet is a best-practice recipe for using cryptography. It combines AES CBC encryption with an HMAC signature, timestamp, and version information to protect data.
<code class="python">from cryptography.fernet import Fernet # Generate a random 32-byte key (securely store it) key = Fernet.generate_key() # Encrypt and decrypt messages using the key def encrypt(message, key): return Fernet(key).encrypt(message.encode()) def decrypt(token, key): return Fernet(key).decrypt(token).decode()</code>
Alternative Approaches:
Data Obscuring:
If data integrity is not a concern, base64 encoding can be used for obscuring.
<code class="python">import base64 def obscure(data): return base64.urlsafe_b64encode(data) def unobscure(obscured): return base64.urlsafe_b64decode(obscured)</code>
Data Integrity:
HMAC signing can ensure data integrity by calculating a signature using a key and hashing algorithm.
<code class="python">import hmac import hashlib def sign(data, key, algorithm=hashlib.sha256): return hmac.new(key, data, algorithm).digest() def verify(signature, data, key, algorithm=hashlib.sha256): return hmac.compare_digest(expected, signature)</code>
Using AES-GCM for Encryption with Integrity
Similar to Fernet, AES-GCM provides encryption and integrity using the Galois / Counter mode block cipher.
<code class="python">from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes from cryptography.hazmat.backends import default_backend def aes_gcm_encrypt(message, key): # ... (Implementation omitted for brevity) def aes_gcm_decrypt(token, key): # ... (Implementation omitted for brevity)</code>
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