1 files changed, 107 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/fuzzer/ecc_helper.h b/comm/third_party/botan/src/fuzzer/ecc_helper.h
new file mode 100644
index 0000000000..4df23a5722
--- /dev/null
+++ b/comm/third_party/botan/src/fuzzer/ecc_helper.h
@@ -0,0 +1,107 @@
+/*
+* (C) 2015,2016 Jack Lloyd
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#ifndef ECC_HELPERS_H_
+#define ECC_HELPERS_H_
+
+#include "fuzzers.h"
+#include <botan/ec_group.h>
+#include <botan/reducer.h>
+#include <botan/numthry.h>
+
+namespace {
+
+inline std::ostream& operator<<(std::ostream& o, const Botan::PointGFp& point)
+   {
+   o << point.get_affine_x() << "," << point.get_affine_y();
+   return o;
+   }
+
+Botan::BigInt decompress_point(bool yMod2,
+                               const Botan::BigInt& x,
+                               const Botan::BigInt& curve_p,
+                               const Botan::BigInt& curve_a,
+                               const Botan::BigInt& curve_b)
+   {
+   Botan::BigInt xpow3 = x * x * x;
+
+   Botan::BigInt g = curve_a * x;
+   g += xpow3;
+   g += curve_b;
+   g = g % curve_p;
+
+   Botan::BigInt z = ressol(g, curve_p);
+
+   if(z < 0)
+      throw Botan::Exception("Could not perform square root");
+
+   if(z.get_bit(0) != yMod2)
+      z = curve_p - z;
+
+   return z;
+   }
+
+void check_ecc_math(const Botan::EC_Group& group,
+                    const uint8_t in[], size_t len)
+   {
+   // These depend only on the group, which is also static
+   static const Botan::PointGFp base_point = group.get_base_point();
+
+   // This is shared across runs to reduce overhead
+   static std::vector<Botan::BigInt> ws(Botan::PointGFp::WORKSPACE_SIZE);
+
+   const size_t hlen = len / 2;
+   const Botan::BigInt a = Botan::BigInt::decode(in, hlen);
+   const Botan::BigInt b = Botan::BigInt::decode(in + hlen, len - hlen);
+   const Botan::BigInt c = a + b;
+
+   const Botan::PointGFp P1 = base_point * a;
+   const Botan::PointGFp Q1 = base_point * b;
+   const Botan::PointGFp R1 = base_point * c;
+
+   const Botan::PointGFp S1 = P1 + Q1;
+   const Botan::PointGFp T1 = Q1 + P1;
+
+   FUZZER_ASSERT_EQUAL(S1, R1);
+   FUZZER_ASSERT_EQUAL(T1, R1);
+
+   const Botan::PointGFp P2 = group.blinded_base_point_multiply(a, fuzzer_rng(), ws);
+   const Botan::PointGFp Q2 = group.blinded_base_point_multiply(b, fuzzer_rng(), ws);
+   const Botan::PointGFp R2 = group.blinded_base_point_multiply(c, fuzzer_rng(), ws);
+   const Botan::PointGFp S2 = P2 + Q2;
+   const Botan::PointGFp T2 = Q2 + P2;
+
+   FUZZER_ASSERT_EQUAL(S2, R2);
+   FUZZER_ASSERT_EQUAL(T2, R2);
+
+   const Botan::PointGFp P3 = group.blinded_var_point_multiply(base_point, a, fuzzer_rng(), ws);
+   const Botan::PointGFp Q3 = group.blinded_var_point_multiply(base_point, b, fuzzer_rng(), ws);
+   const Botan::PointGFp R3 = group.blinded_var_point_multiply(base_point, c, fuzzer_rng(), ws);
+   const Botan::PointGFp S3 = P3 + Q3;
+   const Botan::PointGFp T3 = Q3 + P3;
+
+   FUZZER_ASSERT_EQUAL(S3, R3);
+   FUZZER_ASSERT_EQUAL(T3, R3);
+
+   FUZZER_ASSERT_EQUAL(S1, S2);
+   FUZZER_ASSERT_EQUAL(S1, S3);
+
+   try
+      {
+      const auto yp = decompress_point(true, a, group.get_p(), group.get_a(), group.get_b());
+      const auto pt_p = group.blinded_var_point_multiply(group.point(a, yp), b, fuzzer_rng(), ws);
+
+      const auto yn = -yp;
+      const auto pt_n = group.blinded_var_point_multiply(group.point(a, yn), b, fuzzer_rng(), ws);
+
+      FUZZER_ASSERT_EQUAL(pt_p, -pt_n);
+      }
+   catch(...) {}
+   }
+
+}
+
+#endif