From 320b149b58b185e44b2d3519c95b4ac2ab574746 Mon Sep 17 00:00:00 2001
From: Ted John <ted@brambles.org>
Date: Wed, 23 May 2018 13:18:11 +0100
Subject: [PATCH] Change Windows builds to use CNG API

---
 openrct2.common.props      |  2 +-
 src/openrct2/core/Hash.cpp | 83 +++++++++++++++++++++++---------------
 2 files changed, 51 insertions(+), 34 deletions(-)

diff --git a/openrct2.common.props b/openrct2.common.props
index 4102691a30..3b41540661 100644
--- a/openrct2.common.props
+++ b/openrct2.common.props
@@ -61,7 +61,7 @@
       <AdditionalOptions>/utf-8 /std:c++latest /permissive- /Zc:externConstexpr</AdditionalOptions>
     </ClCompile>
     <Link>
-      <AdditionalDependencies>imm32.lib;version.lib;winmm.lib;crypt32.lib;wldap32.lib;%(AdditionalDependencies)</AdditionalDependencies>
+      <AdditionalDependencies>imm32.lib;version.lib;winmm.lib;crypt32.lib;wldap32.lib;bcrypt.lib;%(AdditionalDependencies)</AdditionalDependencies>
       <AdditionalOptions>/OPT:NOLBR /ignore:4099 %(AdditionalOptions)</AdditionalOptions>
     </Link>
   </ItemDefinitionGroup>
diff --git a/src/openrct2/core/Hash.cpp b/src/openrct2/core/Hash.cpp
index dd8b23f50d..adefba0d61 100644
--- a/src/openrct2/core/Hash.cpp
+++ b/src/openrct2/core/Hash.cpp
@@ -18,12 +18,17 @@
 #include <stdexcept>
 #include <string>
 
-// #define __USE_WINSSL__
+#if defined(_WIN32) && !defined(__USE_OPENSSL__)
+#define __USE_CNG__
+#endif
 
-#ifdef __USE_WINSSL__
+#ifdef __USE_CNG__
+// CNG: Cryptography API: Next Generation (CNG)
+//      available in Windows Vista onwards.
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
-#include <wincrypt.h>
+#include <bcrypt.h>
+#define NT_SUCCESS(Status) (((NTSTATUS)(Status)) >= 0)
 #else
 #include <openssl/evp.h>
 #endif
@@ -31,9 +36,10 @@
 class Sha1Algorithm final : public HashAlgorithm<20>
 {
 private:
-#ifdef __USE_WINSSL__
-    HCRYPTPROV _hProv{};
-    HCRYPTHASH _hHash{};
+#ifdef __USE_CNG__
+    BCRYPT_ALG_HANDLE _hAlg{};
+    BCRYPT_HASH_HANDLE _hHash{};
+    PBYTE _pbHashObject{};
 #else
     EVP_MD_CTX * _ctx{};
 #endif
@@ -41,18 +47,33 @@ private:
 public:
     Sha1Algorithm()
     {
-#ifdef __USE_WINSSL__
-        if (!CryptAcquireContextW(&_hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
+#ifdef __USE_CNG__
+        // TODO BCRYPT_HASH_REUSABLE_FLAG only available from Windows 8
+        auto status = BCryptOpenAlgorithmProvider(&_hAlg, BCRYPT_SHA1_ALGORITHM, nullptr, BCRYPT_HASH_REUSABLE_FLAG);
+        if (!NT_SUCCESS(status))
         {
-            auto dwStatus = GetLastError();
-            throw std::runtime_error("CryptAcquireContext failed : " + std::to_string(dwStatus));
+            throw std::runtime_error("BCryptOpenAlgorithmProvider failed: " + std::to_string(status));
         }
 
-        if (!CryptCreateHash(_hProv, CALG_SHA1, 0, 0, &_hHash))
+        // Calculate the size of the buffer to hold the hash object
+        DWORD cbHashObject{};
+        DWORD cbData{};
+        status = BCryptGetProperty(_hAlg, BCRYPT_OBJECT_LENGTH, (PBYTE)&cbHashObject, sizeof(DWORD), &cbData, 0);
+        if (!NT_SUCCESS(status))
         {
-            auto dwStatus = GetLastError();
-            CryptReleaseContext(_hProv, 0);
-            throw std::runtime_error("CryptCreateHash failed : " + std::to_string(dwStatus));
+            throw std::runtime_error("BCryptGetProperty failed: " + std::to_string(status));
+        }
+
+        // Create a hash
+        _pbHashObject = (PBYTE)HeapAlloc(GetProcessHeap(), 0, cbHashObject);
+        if (_pbHashObject == nullptr)
+        {
+            throw std::bad_alloc();
+        }
+        status = BCryptCreateHash(_hAlg, &_hHash, _pbHashObject, cbHashObject, nullptr, 0, 0);
+        if (!NT_SUCCESS(status))
+        {
+            throw std::runtime_error("BCryptCreateHash failed: " + std::to_string(status));
         }
 #else
         _ctx = EVP_MD_CTX_create();
@@ -70,9 +91,10 @@ public:
 
     ~Sha1Algorithm()
     {
-#ifdef __USE_WINSSL__
-        CryptDestroyHash(_hHash);
-        CryptReleaseContext(_hProv, 0);
+#ifdef __USE_CNG__
+        BCryptCloseAlgorithmProvider(_hAlg, 0);
+        BCryptDestroyHash(_hHash);
+        HeapFree(GetProcessHeap(), 0, _pbHashObject);
 #else
         EVP_MD_CTX_destroy(_ctx);
 #endif
@@ -80,13 +102,9 @@ public:
 
     void Clear() override
     {
-#ifdef __USE_WINSSL__
-        CryptDestroyHash(_hHash);
-        if (!CryptCreateHash(_hProv, CALG_SHA1, 0, 0, &_hHash))
-        {
-            auto dwStatus = GetLastError();
-            throw std::runtime_error("CryptCreateHash failed : " + std::to_string(dwStatus));
-        }
+#ifdef __USE_CNG__
+        // Finishing the current digest clears the state ready for a new digest
+        Finish();
 #else
         if (EVP_DigestInit_ex(_ctx, EVP_sha1(), nullptr) <= 0)
         {
@@ -97,11 +115,11 @@ public:
 
     void Update(const void * data, size_t dataLen) override
     {
-#ifdef __USE_WINSSL__
-        if (!CryptHashData(_hHash, (const BYTE *)data, (DWORD)dataLen, 0))
+#ifdef __USE_CNG__
+        auto status = BCryptHashData(_hHash, (PBYTE)data, (ULONG)dataLen, 0);
+        if (!NT_SUCCESS(status))
         {
-            auto dwStatus = GetLastError();
-            throw std::runtime_error("CryptHashData failed: " + std::to_string(dwStatus));
+            throw std::runtime_error("BCryptHashData failed: " + std::to_string(status));
         }
 #else
         if (EVP_DigestUpdate(_ctx, data, dataLen) <= 0)
@@ -113,13 +131,12 @@ public:
 
     std::array<uint8_t, 20> Finish() override
     {
-#ifdef __USE_WINSSL__
+#ifdef __USE_CNG__
         std::array<uint8_t, 20> result;
-        auto cbHash = (DWORD)result.size();
-        if (!CryptGetHashParam(_hHash, HP_HASHVAL, result.data(), &cbHash, 0))
+        auto status = BCryptFinishHash(_hHash, result.data(), (ULONG)result.size(), 0);
+        if (!NT_SUCCESS(status))
         {
-            auto dwStatus = GetLastError();
-            throw std::runtime_error("CryptGetHashParam failed: " + std::to_string(dwStatus));
+            throw std::runtime_error("BCryptFinishHash failed: " + std::to_string(status));
         }
         return result;
 #else