Cleanup for cert accessors (#118116)

Author: PranavSenthilnathan

src/libraries/Common/src/Interop/Windows/NCrypt/Interop.Properties.cs

@@ -1,12 +1,11 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 using System.Security.Cryptography;
-
+using Internal.Cryptography;
 using Microsoft.Win32.SafeHandles;
 
 internal static partial class Interop
@@ -56,9 +55,7 @@ internal static unsafe ErrorCode NCryptGetIntProperty(SafeNCryptHandle hObject,
         {
             fixed (int* pResult = &result)
             {
-#if NETSTANDARD || NET
-                Debug.Assert(RuntimeInformation.IsOSPlatform(OSPlatform.Windows));
-#endif
+                Debug.Assert(Helpers.IsOSPlatformWindows);
 
                 ErrorCode errorCode = Interop.NCrypt.NCryptGetProperty(
                     hObject,

src/libraries/Common/src/System/Security/Cryptography/CompositeMLDsaImplementation.Windows.cs

@@ -1,7 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Runtime.InteropServices;
+using Internal.Cryptography;
 
 namespace System.Security.Cryptography
 {
@@ -15,60 +15,50 @@ private CompositeMLDsaImplementation(CompositeMLDsaAlgorithm algorithm)
 
         internal static partial bool SupportsAny()
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 return false;
             }
-#endif
 
             return CompositeMLDsaManaged.SupportsAny();
         }
 
         internal static partial bool IsAlgorithmSupportedImpl(CompositeMLDsaAlgorithm algorithm)
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 return false;
             }
-#endif
 
             return CompositeMLDsaManaged.IsAlgorithmSupportedImpl(algorithm);
         }
 
         internal static partial CompositeMLDsa GenerateKeyImpl(CompositeMLDsaAlgorithm algorithm)
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 throw new PlatformNotSupportedException();
             }
-#endif
 
             return CompositeMLDsaManaged.GenerateKeyImpl(algorithm);
         }
 
         internal static partial CompositeMLDsa ImportCompositeMLDsaPublicKeyImpl(CompositeMLDsaAlgorithm algorithm, ReadOnlySpan<byte> source)
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 throw new PlatformNotSupportedException();
             }
-#endif
 
             return CompositeMLDsaManaged.ImportCompositeMLDsaPublicKeyImpl(algorithm, source);
         }
 
         internal static partial CompositeMLDsa ImportCompositeMLDsaPrivateKeyImpl(CompositeMLDsaAlgorithm algorithm, ReadOnlySpan<byte> source)
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 throw new PlatformNotSupportedException();
             }
-#endif
 
             return CompositeMLDsaManaged.ImportCompositeMLDsaPrivateKeyImpl(algorithm, source);
         }

src/libraries/Common/src/System/Security/Cryptography/Helpers.cs

@@ -53,6 +53,14 @@ internal static partial class Helpers
             true;
 #endif
 
+        [SupportedOSPlatformGuard("windows")]
+        internal static bool IsOSPlatformWindows =>
+#if NETFRAMEWORK
+                true;
+#else
+                RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
+#endif
+
         [return: NotNullIfNotNull(nameof(src))]
         public static byte[]? CloneByteArray(this byte[]? src)
         {

src/libraries/Common/src/System/Security/Cryptography/MLDsaCng.cs

@@ -2,8 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics.CodeAnalysis;
-using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
+using Internal.Cryptography;
 
 namespace System.Security.Cryptography
 {
@@ -50,12 +50,10 @@ public MLDsaCng(CngKey key)
 
         private static MLDsaAlgorithm AlgorithmFromHandleWithPlatformCheck(CngKey key, out CngKey duplicateKey)
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 throw new PlatformNotSupportedException();
             }
-#endif
 
             return AlgorithmFromHandle(key, out duplicateKey);
         }

src/libraries/Common/src/System/Security/Cryptography/MLDsaImplementation.Windows.cs

@@ -3,7 +3,7 @@
 
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
-using System.Runtime.InteropServices;
+using Internal.Cryptography;
 using Internal.NativeCrypto;
 using Microsoft.Win32.SafeHandles;
 
@@ -248,12 +248,10 @@ private void ExportKey(string keyBlobType, int expectedKeySize, Span<byte> desti
 
         private static SafeBCryptAlgorithmHandle? OpenAlgorithmHandle()
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 return null;
             }
-#endif
 
             NTSTATUS status = Interop.BCrypt.BCryptOpenAlgorithmProvider(
                 out SafeBCryptAlgorithmHandle hAlgorithm,

src/libraries/Common/src/System/Security/Cryptography/MLKemCng.cs

@@ -1,9 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Diagnostics.CodeAnalysis;
-using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
+using Internal.Cryptography;
 
 namespace System.Security.Cryptography
 {
@@ -50,12 +49,10 @@ public MLKemCng(CngKey key) : base(AlgorithmFromHandleWithPlatformCheck(key, out
 
         private static MLKemAlgorithm AlgorithmFromHandleWithPlatformCheck(CngKey key, out CngKey duplicateKey)
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 throw new PlatformNotSupportedException();
             }
-#endif
 
             return AlgorithmFromHandle(key, out duplicateKey);
         }

src/libraries/Common/src/System/Security/Cryptography/MLKemImplementation.Windows.cs

@@ -3,15 +3,14 @@
 
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
-using System.Runtime.InteropServices;
-using System.Text;
 using Internal.NativeCrypto;
 using Microsoft.Win32.SafeHandles;
 
 using NTSTATUS = Interop.BCrypt.NTSTATUS;
 using KeyBlobMagicNumber = Interop.BCrypt.KeyBlobMagicNumber;
 using KeyBlobType = Interop.BCrypt.KeyBlobType;
 using BCRYPT_MLKEM_KEY_BLOB = Interop.BCrypt.BCRYPT_MLKEM_KEY_BLOB;
+using Internal.Cryptography;
 
 namespace System.Security.Cryptography
 {
@@ -139,12 +138,10 @@ protected override bool TryExportPkcs8PrivateKeyCore(Span<byte> destination, out
 
         private static SafeBCryptAlgorithmHandle? OpenAlgorithmHandle()
         {
-#if !NETFRAMEWORK
-            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (!Helpers.IsOSPlatformWindows)
             {
                 return null;
             }
-#endif
 
             NTSTATUS status = Interop.BCrypt.BCryptOpenAlgorithmProvider(
                 out SafeBCryptAlgorithmHandle hAlgorithm,