From e83591f188f329e9f29f2c5c59ee68a551ac454c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A9o=20Lam?= <leo@innovatetechnologi.es>
Date: Tue, 15 May 2018 21:24:45 +0200
Subject: [PATCH] ec: Avoid exposing internal function

---
 Source/Core/Common/Crypto/ec.cpp | 8 +++++++-
 Source/Core/Common/Crypto/ec.h   | 4 +++-
 Source/Core/Core/IOS/IOSC.cpp    | 4 ++--
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/Source/Core/Common/Crypto/ec.cpp b/Source/Core/Common/Crypto/ec.cpp
index 5fe7e9bb2b..27b9c32325 100644
--- a/Source/Core/Common/Crypto/ec.cpp
+++ b/Source/Core/Common/Crypto/ec.cpp
@@ -313,7 +313,7 @@ static void point_add(u8* r, const u8* p, const u8* q)
   elt_add(ry, s, rx);
 }
 
-void point_mul(u8* d, const u8* a, const u8* b)  // a is bignum
+static void point_mul(u8* d, const u8* a, const u8* b)  // a is bignum
 {
   u32 i;
   u8 mask;
@@ -410,6 +410,12 @@ void ec_priv_to_pub(const u8* k, u8* Q)
   point_mul(Q, k, ec_G);
 }
 
+std::array<u8, 60> ComputeSharedSecret(const u8* private_key, const u8* public_key)
+{
+  std::array<u8, 60> shared_secret;
+  point_mul(shared_secret.data(), private_key, public_key);
+  return shared_secret;
+}
 #ifdef _MSC_VER
 #pragma warning(pop)
 #endif
diff --git a/Source/Core/Common/Crypto/ec.h b/Source/Core/Common/Crypto/ec.h
index 3bf8b9904f..da2281efda 100644
--- a/Source/Core/Common/Crypto/ec.h
+++ b/Source/Core/Common/Crypto/ec.h
@@ -4,10 +4,12 @@
 
 #pragma once
 
+#include <array>
+
 #include "Common/CommonTypes.h"
 
 void generate_ecdsa(u8* R, u8* S, const u8* k, const u8* hash);
 
 void ec_priv_to_pub(const u8* k, u8* Q);
 
-void point_mul(u8* d, const u8* a, const u8* b);
+std::array<u8, 60> ComputeSharedSecret(const u8* private_key, const u8* public_key);
diff --git a/Source/Core/Core/IOS/IOSC.cpp b/Source/Core/Core/IOS/IOSC.cpp
index 7f47421ca8..d344e40b74 100644
--- a/Source/Core/Core/IOS/IOSC.cpp
+++ b/Source/Core/Core/IOS/IOSC.cpp
@@ -250,8 +250,8 @@ ReturnCode IOSC::ComputeSharedKey(Handle dest_handle, Handle private_handle, Han
   }
 
   // Calculate the ECC shared secret.
-  std::array<u8, 0x3c> shared_secret;
-  point_mul(shared_secret.data(), private_entry->data.data(), public_entry->data.data());
+  const std::array<u8, 0x3c> shared_secret =
+      ComputeSharedSecret(private_entry->data.data(), public_entry->data.data());
 
   std::array<u8, 20> sha1;
   mbedtls_sha1(shared_secret.data(), shared_secret.size() / 2, sha1.data());