initial login logic

altcha_utils.py

@@ -0,0 +1,83 @@
+import hashlib
+import hmac
+import secrets
+import base64
+import json
+import time
+
+
+class AltchaChallenge:
+    """Self-hosted Altcha challenge generator and verifier."""
+
+    def __init__(self, hmac_key=None):
+        self.hmac_key = hmac_key or secrets.token_hex(32)
+
+    def create_challenge(self, max_number=100000):
+        """Generate a new Altcha challenge."""
+        salt = secrets.token_hex(12)
+        secret_number = secrets.randbelow(max_number) + 1
+
+        # Create the challenge string that needs to be solved
+        challenge_data = f"{salt}{secret_number}"
+        challenge = hashlib.sha256(challenge_data.encode()).hexdigest()
+
+        # Create signature for verification
+        signature = hmac.new(
+            self.hmac_key.encode(),
+            challenge.encode(),
+            hashlib.sha256
+        ).hexdigest()
+
+        return {
+            "algorithm": "SHA-256",
+            "challenge": challenge,
+            "maxnumber": max_number,
+            "salt": salt,
+            "signature": signature
+        }
+
+    def verify_solution(self, payload):
+        """Verify an Altcha solution payload."""
+        try:
+            # Decode base64 payload
+            decoded = base64.b64decode(payload).decode('utf-8')
+            data = json.loads(decoded)
+
+            algorithm = data.get('algorithm', '')
+            challenge = data.get('challenge', '')
+            number = data.get('number', 0)
+            salt = data.get('salt', '')
+            signature = data.get('signature', '')
+
+            # Verify algorithm
+            if algorithm.upper() != 'SHA-256':
+                return False
+
+            # Verify signature
+            expected_signature = hmac.new(
+                self.hmac_key.encode(),
+                challenge.encode(),
+                hashlib.sha256
+            ).hexdigest()
+
+            if not hmac.compare_digest(signature, expected_signature):
+                return False
+
+            # Verify the solution
+            challenge_data = f"{salt}{number}"
+            computed_challenge = hashlib.sha256(challenge_data.encode()).hexdigest()
+
+            return hmac.compare_digest(computed_challenge, challenge)
+
+        except Exception:
+            return False
+
+
+_altcha_instances = {}
+
+
+def get_altcha(hmac_key):
+    """Get or create an Altcha instance for the given HMAC key."""
+    if hmac_key not in _altcha_instances:
+        _altcha_instances[hmac_key] = AltchaChallenge(hmac_key)
+    return _altcha_instances[hmac_key]