Attack implementation.

[crypto_lab3.git] / src / Tests.cpp

diff --git a/src/Tests.cpp b/src/Tests.cpp
index 92bccd0..2adcd32 100644 (file)
--- a/src/Tests.cpp
+++ b/src/Tests.cpp
@@ -47,6 +47,59 @@ void Tests::runTimeMeasures()
    cout << "Speedup: " << (double(timeRsaStd) / double(timeRsaCRT)) << endl;
 }
 
+void Tests::doAttack()
+{
+   const auto& keys = RsaCrt::generateRSAKeys(RSA_PUBLIC_EXPONENT, KEY_SIZE_BITS);
+   const auto& kPub = keys.first;
+   const auto& kPriv = keys.second;
+   mpz_class message = Rand::randSize(128);
+   mpz_class faultySignature = RsaCrt::signWithFaultySp(message, kPriv);
+   mpz_class correctSignature = RsaCrt::sign(message, kPriv);
+
+   bool attackOK = true;
+
+   cout << "Original:" << endl;
+   cout << " p = " << kPriv.p << endl;
+   cout << " q = " << kPriv.q << endl;
+
+   // At this point the attacker doesn't know the private key but he has intercepted the message and the faulty signature.
+   {
+      mpz_class faultySignaturePowerE;
+      mpz_pow_ui(faultySignaturePowerE.get_mpz_t(), faultySignature.get_mpz_t(), RSA_PUBLIC_EXPONENT);
+      mpz_class messageMinuxFaultySignaturePowerE = message - faultySignaturePowerE;
+      mpz_class q;
+      mpz_gcd(q.get_mpz_t(), messageMinuxFaultySignaturePowerE.get_mpz_t(), kPub.n.get_mpz_t());
+      mpz_class p = kPub.n / q;
+
+      cout << "Found with a faulty signature:" << endl;
+      cout << " p = " << p << endl;
+      cout << " q = " << q << endl;
+
+      attackOK = attackOK && kPriv.p == p && kPriv.q == q; // With p and q we can recreate the original private key.
+   }
+
+   // Try the attack with a correct signature.
+   {
+      mpz_class correctSignaturePowerE;
+      mpz_pow_ui(correctSignaturePowerE.get_mpz_t(), correctSignature.get_mpz_t(), RSA_PUBLIC_EXPONENT);
+      mpz_class messageMinuxCorrectSignaturePowerE = message - correctSignaturePowerE;
+      mpz_class q;
+      mpz_gcd(q.get_mpz_t(), messageMinuxCorrectSignaturePowerE.get_mpz_t(), kPub.n.get_mpz_t());
+      mpz_class p = kPub.n / q;
+
+      cout << "Found with a correct signature:" << endl;
+      cout << " p = " << p << endl; // Equal to 1.
+      cout << " q = " << q << endl; // Equal to n.
+
+      attackOK = attackOK && kPriv.p != p && kPriv.q != q;
+   }
+
+   if (attackOK)
+      cout << "Attack successful" << endl;
+   else
+      cout << "Attack failed" << endl;
+}
+
 bool Tests::rsaStandard()
 {
    const auto& keys = RsaStd::generateRSAKeys(RSA_PUBLIC_EXPONENT, KEY_SIZE_BITS);