Add Wireguard KeyGen Util

tests/AS1024.Wireguard.Utils.Tests/AS1024.Wireguard.Utils.Tests.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.4" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="xunit" Version="2.9.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Xunit" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\AS1024.Wireguard.Utils\AS1024.Wireguard.Utils.csproj" />
+  </ItemGroup>
+
+</Project>

tests/AS1024.Wireguard.Utils.Tests/WireGuardKeyUtilsTests.cs

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+namespace AS1024.Wireguard.Utils.Tests;
+
+public class WireGuardKeyUtilsTests
+{
+    [Fact]
+    public void RoundTrip()
+    {
+        var priv = WireGuardKeyUtils.GeneratePrivateKey();
+        var pub  = WireGuardKeyUtils.GetPublicKey(priv);
+
+        var privB64 = Convert.ToBase64String(priv);
+        Assert.Equal(priv, WireGuardKeyUtils.FromBase64(privB64));
+        Assert.Equal(WireGuardKeyUtils.KeySize, pub.Length);
+    }
+
+    [Fact]
+    public void Rfc7748Vector()
+    {
+        // RFC 7748 §6.1.
+        var priv     = Convert.FromHexString("77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a");
+        var expected = Convert.FromHexString("8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a");
+
+        Assert.Equal(expected, WireGuardKeyUtils.GetPublicKey(priv));
+    }
+
+    [Fact]
+    public void RejectsWrongLength()
+    {
+        Assert.Throws<ArgumentException>(() => WireGuardKeyUtils.GetPublicKey(new byte[31]));
+    }
+}