Replacing Yubico.DotnetPolyFills with PolySharp. Bumping LanguageVersion to C#12.

.editorconfig

@@ -25,6 +25,9 @@ file_header_template = Copyright 2024 Yubico AB\n\nLicensed under the Apache Lic
 # C# files
 [*.cs]
 
+# Use concrete types when possible for improved performance
+dotnet_diagnostic.CA1859.severity = suggestion
+
 #### Core EditorConfig Options ####
 
 # We can't do this until C# 9.
@@ -338,6 +341,9 @@ csharp_style_var_for_built_in_types = true:suggestion
 csharp_style_unused_value_expression_statement_preference = unused_local_variable:none
 resharper_for_simple_types = use_var
 
+# CA1860: Avoid using 'Enumerable.Any()' extension method
+dotnet_diagnostic.CA1860.severity = suggestion
+
 # CA1707: Identifiers should not contain underscores
 dotnet_diagnostic.ca1707.severity = none
 

.github/workflows/build.yml

@@ -65,8 +65,8 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-dotnet@v4
         with:
-          global-json-file: global.json
-
+          global-json-file: "./global.json"
+          dotnet-version: 6.0.300
       - name: Add local NuGet repository
         run: dotnet nuget add source --username ${{ github.actor }} --password ${{ secrets.GITHUB_TOKEN }} --store-password-in-clear-text --name github "https://nuget.pkg.github.com/Yubico/index.json"
 

.github/workflows/test-macos.yml

@@ -30,7 +30,8 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-dotnet@v4
         with:
-          global-json-file: global.json
+          global-json-file: "./global.json"
+          dotnet-version: 6.0.300
 
       - name: Add local NuGet repository
         run: dotnet nuget add source --username ${{ github.actor }} --password ${{ secrets.GITHUB_TOKEN }} --store-password-in-clear-text --name github "https://nuget.pkg.github.com/Yubico/index.json"

.github/workflows/test-ubuntu.yml

@@ -30,7 +30,8 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-dotnet@v4
         with:
-          global-json-file: global.json
+          global-json-file: "./global.json"
+          dotnet-version: 6.0.300
 
       - name: Add local NuGet repository
         run: dotnet nuget add source --username ${{ github.actor }} --password ${{ secrets.GITHUB_TOKEN }} --store-password-in-clear-text --name github "https://nuget.pkg.github.com/Yubico/index.json"

.github/workflows/test-windows.yml

@@ -30,7 +30,9 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-dotnet@v4
         with:
-          global-json-file: global.json
+          global-json-file: "./global.json"
+          dotnet-version: 6.0.300
+
       - name: Add local NuGet repository
         run: dotnet nuget add source --username ${{ github.actor }} --password ${{ secrets.GITHUB_TOKEN }} --store-password-in-clear-text --name github "https://nuget.pkg.github.com/Yubico/index.json"
 

.github/workflows/verify-code-style.yml

@@ -30,13 +30,15 @@ on:
 jobs:
   verify-code-style:
     name: "Verify code style"
-    runs-on: windows-latest
+    runs-on: windows-2019
 
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-dotnet@v4
         with:
-          global-json-file: global.json
+          global-json-file: "./global.json"
+          dotnet-version: 6.0.300
+
       - name: Add local NuGet repository
         run: dotnet nuget add source --username ${{ github.actor }} --password ${{ secrets.GITHUB_TOKEN }} --store-password-in-clear-text --name github "https://nuget.pkg.github.com/Yubico/index.json"
       #- name: Build Yubico.NET.SDK.sln

Yubico.Core/src/Yubico.Core.csproj

@@ -107,13 +107,19 @@ limitations under the License. -->
 
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Bcl.HashCode" Version="1.1.1"/>
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="7.0.1" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All" />
+    <PackageReference Include="PolySharp" Version="1.14.1">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
     <PackageReference Include="System.Memory" Version="4.5.5" />
+    <PackageReference Include="System.Runtime.InteropServices.RuntimeInformation" Version="4.3.0"/>
     <PackageReference Include="System.Security.Principal.Windows" Version="5.0.0" />
     <!-- The wildcard version tag allows us to include the latest minor and pre-release versions -->
     <PackageReference Include="Yubico.NativeShims" Version="1.*-*" />
-    <ProjectReference Include="..\..\Yubico.DotNetPolyfills\src\Yubico.DotNetPolyfills.csproj" />
+    <!--    <ProjectReference Include="..\..\Yubico.DotNetPolyfills\src\Yubico.DotNetPolyfills.csproj" />-->
   </ItemGroup>
 
   <ItemGroup Label="Expose internal test hooks to Unit Test projects">
@@ -133,4 +139,8 @@ limitations under the License. -->
     </AssemblyAttribute>
 
   </ItemGroup>
+
+  <ItemGroup>
+    <Reference Include="System.Security" Condition="'$(TargetFramework)' == 'net47'"/>
+  </ItemGroup>
 </Project>

Yubico.Core/src/Yubico/Core/Buffers/MultiString.cs

@@ -24,6 +24,8 @@ namespace Yubico.Core.Buffers
     /// </summary>
     public static class MultiString
     {
+        private static readonly char[] _separator = ['\0'];
+
         /// <summary>
         /// Converts the byte array representing a multi-null-terminated string and return them as
         /// .NET strings.
@@ -40,7 +42,7 @@ public static string[] GetStrings(byte[] value, Encoding encoding)
 
             return encoding
                 .GetString(value)
-                .Split(new char[] { '\0' }, StringSplitOptions.RemoveEmptyEntries);
+                .Split(_separator, StringSplitOptions.RemoveEmptyEntries);
         }
 
         /// <summary>

Yubico.Core/src/Yubico/Core/Cryptography/CryptographicOperations.cs

@@ -0,0 +1,63 @@
+// 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.Runtime.CompilerServices;
+
+namespace Yubico.Core.Cryptography;
+
+/// <summary>
+///     Source:
+///     https://github.com/dotnet/runtime/blob/16b456426dfb5212a24bfb78bfd5d9adfcc95185/src/libraries/System.Security.Cryptography.Primitives/src/System/Security/Cryptography/CryptographicOperations.cs
+/// </summary>
+public static class CryptographicOperations
+{
+    /// <summary>
+    ///     Determine the equality of two byte sequences in an amount of time which depends on
+    ///     the length of the sequences, but not the values.
+    /// </summary>
+    /// <param name="left">The first buffer to compare.</param>
+    /// <param name="right">The second buffer to compare.</param>
+    /// <returns>
+    ///     <c>true</c> if <paramref name="left" /> and <paramref name="right" /> have the same
+    ///     values for <see cref="ReadOnlySpan{T}.Length" /> and the same contents, <c>false</c>
+    ///     otherwise.
+    /// </returns>
+    /// <remarks>
+    ///     This method compares two buffers' contents for equality in a manner which does not
+    ///     leak timing information, making it ideal for use within cryptographic routines.
+    ///     This method will short-circuit and return <c>false</c> only if <paramref name="left" />
+    ///     and <paramref name="right" /> have different lengths.
+    ///     Fixed-time behavior is guaranteed in all other cases, including if <paramref name="left" />
+    ///     and <paramref name="right" /> reference the same address.
+    /// </remarks>
+    [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.NoOptimization)]
+    public static bool FixedTimeEquals(ReadOnlySpan<byte> left, ReadOnlySpan<byte> right)
+    {
+        // NoOptimization because we want this method to be exactly as non-short-circuiting
+        // as written.
+        //
+        // NoInlining because the NoOptimization would get lost if the method got inlined.
+
+        if (left.Length != right.Length)
+        {
+            return false;
+        }
+
+        int length = left.Length;
+        int accum = 0;
+
+        for (int i = 0; i < length; i++)
+        {
+            accum |= left[i] - right[i];
+        }
+
+        return accum == 0;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.NoOptimization)]
+
+    // NoOptimize to prevent the optimizer from deciding this call is unnecessary
+    // NoInlining to prevent the inliner from forgetting that the method was no-optimize
+    public static void ZeroMemory(Span<byte> buffer) => buffer.Clear();
+}

Yubico.Core/src/Yubico/Core/Devices/Hid/LinuxHidIOReportConnection.cs

@@ -14,8 +14,8 @@
 
 using System;
 using System.Globalization;
-using System.Security.Cryptography;
 using Yubico.Core.Buffers;
+using Yubico.Core.Cryptography;
 using Yubico.Core.Logging;
 using Yubico.PlatformInterop;
 

Yubico.Core/src/Yubico/Core/Devices/Hid/WindowsHidDevice.cs

@@ -76,7 +76,9 @@ private void ResolveIdsFromInstancePath(string instancePath)
             // 012345678901234567890123456789
             //             ^---     ^---
 
+            #pragma warning disable CA1862
             if (instancePath.ToUpperInvariant().Contains("VID") && instancePath.ToUpperInvariant().Contains("HID"))
+            #pragma warning restore CA1862
             {
                 // If this fails, vendorId will be 0.
                 _ = TryGetHexShort(instancePath, 12, 4, out ushort vendorId);

Yubico.Core/src/Yubico/Core/Devices/SmartCard/DesktopSmartCardDeviceListener.cs

@@ -30,15 +30,16 @@ namespace Yubico.Core.Devices.SmartCard
     internal class DesktopSmartCardDeviceListener : SmartCardDeviceListener, IDisposable
     {
         private readonly Logger _log = Log.GetLogger();
-
+        
         // The resource manager context.
         private SCardContext _context;
-
+        
         // The active smart card readers.
         private SCARD_READER_STATE[] _readerStates;
-
-        private bool _isListening;
         private Thread? _listenerThread;
+        private bool _isListening;
+        private bool _disposedValue; // To detect redundant calls
+        private static readonly string[] _readerNames = ["\\\\?\\Pnp\\Notifications"];
 
         /// <summary>
         /// Constructs a <see cref="SmartCardDeviceListener"/>.
@@ -74,16 +75,19 @@ public DesktopSmartCardDeviceListener()
         /// </summary>
         private void StartListening()
         {
-            if (!_isListening)
+            if (_isListening)
             {
-                _listenerThread = new Thread(ListenForReaderChanges)
-                {
-                    IsBackground = true
-                };
-                _isListening = true;
-                Status = DeviceListenerStatus.Started;
-                _listenerThread.Start();
+                return;
             }
+
+            _listenerThread = new Thread(ListenForReaderChanges)
+            {
+                IsBackground = true
+            };
+
+            _isListening = true;
+            Status = DeviceListenerStatus.Started;
+            _listenerThread.Start();
         }
 
         // This method is the delegate sent to the new Thread.
@@ -104,25 +108,26 @@ private void ListenForReaderChanges()
         }
 
         #region IDisposable Support
-
-        private bool _disposedValue; // To detect redundant calls
-
+
         /// <summary>
         /// Disposes the objects.
         /// </summary>
         /// <param name="disposing"></param>
         protected virtual void Dispose(bool disposing)
         {
-            if (!_disposedValue)
+            if (_disposedValue)
             {
-                if (disposing)
-                {
-                    uint _ = SCardCancel(_context);
-                    _context.Dispose();
-                    StopListening();
-                }
-                _disposedValue = true;
+                return;
             }
+
+            if (disposing)
+            {
+                uint _ = SCardCancel(_context);
+                _context.Dispose();
+                StopListening();
+            }
+
+            _disposedValue = true;
         }
 
         ~DesktopSmartCardDeviceListener()
@@ -192,7 +197,7 @@ private bool CheckForUpdates(int timeout, bool usePnpWorkaround)
                 SCARD_READER_STATE[] removedReaderStates = newStates.Except(eventStateList, new ReaderStateComparer()).ToArray();
 
                 // Don't get status changes if there are no updates in state list.
-                if (!addedReaderStates.Any() && !removedReaderStates.Any())
+                if (addedReaderStates.Length == 0 && removedReaderStates.Length == 0)
                 {
                     break;
                 }
@@ -214,7 +219,7 @@ private bool CheckForUpdates(int timeout, bool usePnpWorkaround)
                 // Only call get status change if a new reader was added. If nothing was added,
                 // we would otherwise hang / timeout here because all changes (in SCard's mind)
                 // have been dealt with.
-                if (addedReaderStates.Any())
+                if (addedReaderStates.Length != 0)
                 {
                     _log.LogInformation("Additional smart card readers were found. Calling GetStatusChange for more information.");
                     getStatusChangeResult = SCardGetStatusChange(_context, 0, updatedStates, updatedStates.Length);
@@ -280,7 +285,7 @@ private bool CheckForUpdates(int timeout, bool usePnpWorkaround)
         // us of the change.
         private bool UsePnpWorkaround()
         {
-            SCARD_READER_STATE[] testState = SCARD_READER_STATE.CreateFromReaderNames(new[] { "\\\\?\\Pnp\\Notifications" });
+            SCARD_READER_STATE[] testState = SCARD_READER_STATE.CreateFromReaderNames(_readerNames);
             _ = SCardGetStatusChange(_context, 0, testState, testState.Length);
             bool usePnpWorkaround = testState[0].EventState.HasFlag(SCARD_STATE.UNKNOWN);
             return usePnpWorkaround;

Yubico.Core/src/Yubico/Core/Tlv/TlvSubElement.cs

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 using System;
-using System.Security.Cryptography;
+using Yubico.Core.Cryptography;
 
 namespace Yubico.Core.Tlv
 {

Yubico.Core/src/Yubico/PlatformInterop/SdkPlatformInfo.cs

@@ -49,18 +49,19 @@ public static SdkPlatform OperatingSystem
                 {
                     return SdkPlatform.Windows;
                 }
-                else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX) ||
+                    RuntimeInformation.IsOSPlatform(OSPlatform.Create("MACCATALYST")))
                 {
                     return SdkPlatform.MacOS;
                 }
-                else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
                 {
                     return SdkPlatform.Linux;
                 }
-                else
-                {
-                    return SdkPlatform.Unknown;
-                }
+
+                return SdkPlatform.Unknown;
             }
         }
 

Yubico.Core/src/Yubico/PlatformInterop/Windows/Cfgmgr32/CmDevice.cs

@@ -213,9 +213,7 @@ private void ResolveHidUsages()
 
         private static IList<string> GetDevicePaths(Guid classGuid, string? deviceInstanceId)
         {
-            CmErrorCode errorCode;
-
-            errorCode = CM_Get_Device_Interface_List_Size(
+            CmErrorCode errorCode = CM_Get_Device_Interface_List_Size(
                 out int bufferLength,
                 classGuid,
                 deviceInstanceId,