Separate BCryptGenRandom out of Cng.cs

As part of #1739, this commit begins to refactor Cng.cs, starting by pulling out the functionality needed for RandomNumberGenerator.  The assembly was being filled with all of the Cng code, when in reality it only needed a very small amount of it.  And since the assembly doesn't have any string resources, I also modified the .csproj to suppress the buildtools inclusion of the common resources support.

As a result of the removals, this change boosts the code coverage number of System.Security.Cryptography.RandomNumberGenerator.dll from 13% to 96%.

(Note that there are still copies of the code in Interop.NTSTATUS.cs in Cng.cs, due to other dependencies in Cng.cs that I didn't want to change.  As we refactor Cng.cs further, we can remove those copies.)

Author: stephentoub

src/Common/src/Interop/Windows/BCrypt/Cng.cs

@@ -129,14 +129,6 @@ public static int GetHashSizeInBytes(this SafeHashHandle hHash)
             }
         }
 
-        public static void BCryptGenRandom(byte[] buffer)
-        {
-            const int BCRYPT_USE_SYSTEM_PREFERRED_RNG = 0x00000002;
-            NTSTATUS ntStatus = Interop.BCryptGenRandom(IntPtr.Zero, buffer, buffer.Length, BCRYPT_USE_SYSTEM_PREFERRED_RNG);
-            if (ntStatus != NTSTATUS.STATUS_SUCCESS)
-                throw CreateCryptographicException(ntStatus);
-        }
-
         public static SafeKeyHandle BCryptImportKey(this SafeAlgorithmHandle hAlg, byte[] key)
         {
             unsafe
@@ -310,9 +302,6 @@ private static class Interop
             [DllImport(CngDll, CharSet = CharSet.Unicode)]
             public static extern unsafe NTSTATUS BCryptSetProperty(SafeBCryptHandle hObject, String pszProperty, String pbInput, int cbInput, int dwFlags);
 
-            [DllImport(CngDll, CharSet = CharSet.Unicode)]
-            public static extern NTSTATUS BCryptGenRandom(IntPtr hAlgorithm, [In, Out] byte[] pbBuffer, int cbBuffer, int dwFlags);
-
             [DllImport(CngDll, CharSet = CharSet.Unicode)]
             public static extern NTSTATUS BCryptImportKey(SafeAlgorithmHandle hAlgorithm, IntPtr hImportKey, String pszBlobType, out SafeKeyHandle hKey, IntPtr pbKeyObject, int cbKeyObject, byte[] pbInput, int cbInput, int dwFlags);
 

src/Common/src/Interop/Windows/BCrypt/Interop.BCryptGenRandom.cs

@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Runtime.InteropServices;
+
+internal partial class Interop
+{
+    internal partial class BCrypt
+    {
+        internal static void BCryptGenRandom(byte[] buffer)
+        {
+            NTSTATUS ntStatus = BCryptGenRandom(IntPtr.Zero, buffer, buffer.Length, BCRYPT_USE_SYSTEM_PREFERRED_RNG);
+            if (ntStatus != NTSTATUS.STATUS_SUCCESS)
+                throw CreateCryptographicException(ntStatus);
+        }
+
+        private const int BCRYPT_USE_SYSTEM_PREFERRED_RNG = 0x00000002;
+
+        [DllImport(Libraries.BCrypt, CharSet = CharSet.Unicode)]
+        private static extern NTSTATUS BCryptGenRandom(IntPtr hAlgorithm, [In, Out] byte[] pbBuffer, int cbBuffer, int dwFlags);
+    }
+}

src/Common/src/Interop/Windows/BCrypt/Interop.NTSTATUS.cs

@@ -0,0 +1,25 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Security.Cryptography;
+
+internal partial class Interop
+{
+    internal partial class BCrypt
+    {
+        private enum NTSTATUS : uint
+        {
+            STATUS_SUCCESS = 0x0,
+            STATUS_NOT_FOUND = 0xc0000225,
+            STATUS_INVALID_PARAMETER = 0xc000000d,
+            STATUS_NO_MEMORY = 0xc0000017,
+        }
+
+        private static Exception CreateCryptographicException(NTSTATUS ntStatus)
+        {
+            int hr = ((int)ntStatus) | 0x01000000;
+            return new CryptographicException(hr);
+        }
+    }
+}

src/Common/src/Interop/Windows/Interop.Libraries.cs

@@ -5,6 +5,7 @@ internal static partial class Interop
 {
     private static class Libraries
     {
+        internal const string BCrypt = "BCrypt.dll";
         internal const string Console_L1 = "api-ms-win-core-console-l1-1-0.dll";
         internal const string Console_L2 = "api-ms-win-core-console-l2-1-0.dll";
         internal const string CoreFile_L1 = "api-ms-win-core-file-l1-1-0.dll";

src/System.Security.Cryptography.RandomNumberGenerator/src/System.Security.Cryptography.RandomNumberGenerator.csproj

@@ -10,6 +10,7 @@
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <CLSCompliant>false</CLSCompliant>
+    <SkipCommonResourcesIncludes>true</SkipCommonResourcesIncludes>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Linux_Debug|AnyCPU' " />
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Linux_Release|AnyCPU' " />
@@ -22,8 +23,14 @@
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetsWindows)' == 'true' ">
     <Compile Include="System\Security\Cryptography\RNGCryptoServiceProvider.Windows.cs" />
-    <Compile Include="$(CommonPath)\Interop\Windows\BCrypt\Cng.cs">
-      <Link>Common\Interop\Windows\BCrypt\Cng.cs</Link>
+    <Compile Include="$(CommonPath)\Interop\Windows\Interop.Libraries.cs">
+      <Link>Common\Interop\Windows\Interop.Libraries.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)\Interop\Windows\BCrypt\Interop.BCryptGenRandom.cs">
+      <Link>Common\Interop\Windows\BCrypt\Interop.BCryptGenRandom.cs</Link>
+    </Compile>
+    <Compile Include="$(CommonPath)\Interop\Windows\BCrypt\Interop.NTSTATUS.cs">
+      <Link>Common\Interop\Windows\BCrypt\Interop.NTSTATUS.cs</Link>
     </Compile>
   </ItemGroup>
   <ItemGroup Condition=" '$(TargetsUnix)' == 'true' ">

src/System.Security.Cryptography.RandomNumberGenerator/src/System/Security/Cryptography/RNGCryptoServiceProvider.Windows.cs

@@ -1,10 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-using System.Diagnostics;
-
-using Internal.NativeCrypto;
-
 namespace System.Security.Cryptography
 {
     internal sealed class RNGCryptoServiceProvider : RandomNumberGenerator
@@ -14,9 +10,8 @@ public sealed override void GetBytes(byte[] data)
             ValidateGetBytesArgs(data);
             if (data.Length > 0)
             {
-                Cng.BCryptGenRandom(data);
+                Interop.BCrypt.BCryptGenRandom(data);
             }
         }
     }
 }
-