#include #include // Simulated Lindell17 protocol implementation class Lindell17Protocol { public: // Simulated ECDSA constant static const int q = 256; // Simulated server's secret share int x2; Lindell17Protocol(int secretShare) : x2(secretShare) {} // Simulated signature process bool sign(int msg, int r) { // Simulate abort mechanism if (rand() % 10 < 2) { std::cout << "Signature failed due to abort.\n"; return false; } int k1 = 2; int rho = (r % 2 == 0) ? r + q : r; int C = hash(msg) + r * x2 * (inverse(k1, q) % q) + rho * x2 * (inverse(k1, q) % q); // Simulate signature validation return validateSignature(C); } // Simulated hash function int hash(int input) { return input % q; } // Simulated inverse calculation int inverse(int num, int mod) { for (int i = 1; i < mod; ++i) { if ((num * i) % mod == 1) { return i; } } return 1; } // Simulated signature validation bool validateSignature(int C) { return rand() % 2 == 0; } }; int main() { srand(time(0)); // Simulated server's secret share int secretShare = rand() % Lindell17Protocol::q; Lindell17Protocol attacker(secretShare); // Simulate extracting each bit of the secret share std::vector extractedBits; for (int i = 0; i < 256; ++i) { int msg = rand(); // Simulated message int r = rand(); // Simulated public nonce if (attacker.sign(msg, r)) { extractedBits.push_back(0); } else { extractedBits.push_back(1); } } // Print the extracted bits std::cout << "Extracted bits: "; for (int bit : extractedBits) { std::cout << bit; } std::cout << std::endl; return 0; }