feature: kavach recovery key implemented

src/lighthouseweb3/__init__.py

@@ -2,6 +2,10 @@
 
 import os
 import io
+from typing import Dict, List
+
+from .functions.encryption import recover_key as recoveryKey
+
 from .functions import (
     upload as d,
     deal_status, 
@@ -224,3 +228,17 @@ def getTagged(self, tag: str):
         except Exception as e:
             raise e
 
+
+class Kavach:
+    @staticmethod
+    def recoverKey(shards: List[Dict[str, str]]) -> Dict[str, str]:
+        """
+        Recovers the master key from a list of key shards using Lagrange interpolation.
+
+        :param shards: List of dictionaries containing 'key' and 'index' as hex strings
+        :return: Dictionary containing the recovered master key
+        """
+        try:
+            return recoveryKey.recover_key(shards)
+        except Exception as e:
+            raise e

src/lighthouseweb3/functions/encryption/recover_key.py

@@ -0,0 +1,29 @@
+from typing import List, Dict
+from py_ecc.optimized_bls12_381.optimized_curve import curve_order
+
+def recover_key(shards: List[Dict[str, str]]) -> Dict[str, str]:
+
+    try:
+        # Convert hex strings to integers
+        x_coords = [int(shard['index'], 16) for shard in shards]
+        y_coords = [int(shard['key'], 16) for shard in shards]
+
+        # Lagrange interpolation to recover the constant term (secret)
+        def lagrange_interpolate(x: int, x_s: List[int], y_s: List[int], p: int) -> int:
+            total = 0
+            for i in range(len(x_s)):
+                numerator = denominator = 1
+                for j in range(len(x_s)):
+                    if i != j:
+                        numerator = (numerator * (x - x_s[j])) % p
+                        denominator = (denominator * (x_s[i] - x_s[j])) % p
+                l = (y_s[i] * numerator * pow(denominator, -1, p)) % p
+                total = (total + l) % p
+            return total
+
+        # Recover the master key at x=0
+        master_key = lagrange_interpolate(0, x_coords, y_coords, curve_order)
+
+        return {"masterKey": hex(master_key)[2:].zfill(64), "error": None}
+    except Exception as e:
+        return {"masterKey": None, "error":e}

tests/test_encryption/test_recover_key.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+import unittest
+from src.lighthouseweb3 import Kavach
+
+
+class TestKavachRecoverKey(unittest.TestCase):
+  def test_recover_key(self):
+    """test recover key with valid shards"""
+    known_key = "0b2ccf87909bd1215858e5c0ec99359cadfcf918a4fac53e3e88e9ec28bec678"
+    result = [{'key': '20e2fdc23015c6c78272174be8639b49275e0dbf0479dde60950832ef18bb661', 'index': '9d956693217a5443ba1823151f0924d5a59aaa009cef8cd0f97d3e1a6d279140'}, {'key': '508e1ddc5c06b7e2053d600c4c5da6627778b371784ef712cb8c96f7deae9ce4', 'index': '61a82e98b2c19d13f7edeb1c79c36c40378a5ec2df2e818c6cbd0ead5e548178'}, {'key': '0aca075033a6d257cbac7564c01637b111268f8d42974e5bd765004cc840d359', 'index': '8339e90fc50c9b6b4d650bd03187f4cb4e42e616d1acb6c77dae037764997adb'}, {'key': '4c8a56b19e66a4d533946fe3bb4929556258869f939769514c0abdf8d22d1fa2', 'index': '283985072fcb14bcaf20f5c393d4af5f49a6d2cae472fb28038507f174f7d22d'}, {'key': '2ab718fe611b09eae351a53969364df1bd754f345de87839d22bbcae6b8d091f', 'index': '107dd8993e24875227e024e3352ab7333a766b93cd646f51bc68a2ebc682c64a'}]
+
+    recovered = Kavach.recoverKey(result)
+    self.assertEqual(recovered["masterKey"], known_key, "Recovered key should match original")
+
+  def test_recover_key_invalid(self):
+    """test recover key with invalid shards"""
+    known_key = "1b2ccf87909bd1215858e5c0ec99359cadfcf918a4fac53e3e88e9ec28bec678"
+    result = [{'key': '20e2fdc23015c6c78272174be8639b49275e0dbf0479dde60950832ef18bb661', 'index': '9d956693217a5443ba1823151f0924d5a59aaa009cef8cd0f97d3e1a6d279140'}, {'key': '508e1ddc5c06b7e2053d600c4c5da6627778b371784ef712cb8c96f7deae9ce4', 'index': '61a82e98b2c19d13f7edeb1c79c36c40378a5ec2df2e818c6cbd0ead5e548178'}, {'key': '0aca075033a6d257cbac7564c01637b111268f8d42974e5bd765004cc840d359', 'index': '8339e90fc50c9b6b4d650bd03187f4cb4e42e616d1acb6c77dae037764997adb'}, {'key': '4c8a56b19e66a4d533946fe3bb4929556258869f939769514c0abdf8d22d1fa2', 'index': '283985072fcb14bcaf20f5c393d4af5f49a6d2cae472fb28038507f174f7d22d'}, {'key': '2ab718fe611b09eae351a53969364df1bd754f345de87839d22bbcae6b8d091f', 'index': '107dd8993e24875227e024e3352ab7333a766b93cd646f51bc68a2ebc682c64a'}] 
+
+    recovered = Kavach.recoverKey(result)
+    self.assertNotEqual(recovered["masterKey"], known_key, "Recovered key should not match original")