Tweak argon2 settings

src/anonchat/__init__.py

@@ -46,7 +46,12 @@ elif app.config['SESSION_TYPE'] == 'filesystem':
 app.config['SESSION_KEY_PREFIX'] = 'anonchat_session:'
 
 # Initialize password hasher
-password_hasher = PasswordHasher()
+# Parameters source: https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html#argon2id
+password_hasher = PasswordHasher(
+    time_cost=2,
+    memory_cost=19456,
+    parallelism=1
+)
 
 # Initialize session with Redis storage
 Session(app)

src/anonchat/models.py

@@ -32,10 +32,18 @@ class Admin(db.Model):
         """Hash a password using Argon2id"""
         return password_hasher.hash(password)
     
+    def rehash_password(self, password):
+        """Rehash a password using Argon2id"""
+        self.password_hash = self.hash_password(password)
+        db.session.add(self)
+        db.session.commit()
+    
     def verify_password(self, password):
         """Verify a password against the stored hash"""
         try:
             password_hasher.verify(self.password_hash, password)
+            if password_hasher.check_needs_rehash(self.password_hash):
+                self.rehash_password(password)
             return True
         except argon2.exceptions.VerifyMismatchError:
             return False