Fri Jun 23 16:28:43 CEST 2023

src/lib/crypto.py

@@ -0,0 +1,76 @@
+"""
+    Cryptography related stuff - mostly
+    encrypting and decrypting user data.
+"""
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
+from cryptography.fernet import Fernet
+import base64
+import os
+
+def get_key(password: str) -> bytes:
+    """
+        Derives a bytes key
+        from a given password.
+
+        Useful when you want
+        to generate the same
+        key over and over again.
+        E.g. to encrypt/decrypt
+        locally stored user data.
+    """
+
+    password = password.encode()
+
+    salt = b'?\x0f\xa1\x97otT\xe48\xc9O\xb4\x1f\xef\xf5\xea'
+
+    kdf = PBKDF2HMAC(
+        algorithm=hashes.SHA256,
+        length=32,
+        salt=salt,
+        iterations=100000,
+        backend=default_backend()
+    )
+
+    key = base64.urlsafe_b64encode(kdf.derive(password))
+    return key
+
+def encrypt_and_write_to_file(password: str, strdata: str, file_path: str) -> bool:
+    """
+        Encrypts the given string data
+        and stores them in a file.
+    """
+
+    try:
+        key = get_key(password)
+    
+        f = Fernet(key)
+
+        encrypted = f.encrypt(strdata.encode())
+        
+        with open(file_path, "wb") as ef:
+            ef.write(encrypted)
+
+        return 0
+    except:
+        return 1
+
+def read_from_file_and_decrypt(password: str, file_path: str) -> str:
+    """
+        Reads contents of an encrypted file
+        and decrypts them.
+    """
+
+    try:
+        key = get_key(password)
+
+        f = Fernet(key)
+
+        with open(file_path, "rb") as ef:
+            decrypted = f.decrypt(ef.read())
+
+        return decrypted.decode()
+    except:
+        return ""