Improve Create

AesExtra/AesCmac.cs

@@ -2,6 +2,7 @@
 //
 // SPDX-License-Identifier: MIT
 
+using System.Diagnostics.CodeAnalysis;
 using System.Security.Cryptography;
 
 namespace Dorssel.Security.Cryptography;
@@ -14,18 +15,21 @@ public sealed class AesCmac
 {
     const int BLOCKSIZE = 16; // bytes
 
-    /// <inheritdoc cref="KeyedHashAlgorithm.Create()" />
-    /// <remarks>This static override defaults to <see cref="AesCmac" />.</remarks>
-    public static new KeyedHashAlgorithm Create()
+    /// <inheritdoc cref="KeyedHashAlgorithm.Create()" path="/summary" />
+    /// <returns>A new <see cref="AesCmac" /> instance.</returns>
+    public static new AesCmac Create()
     {
         return new AesCmac();
     }
 
     /// <inheritdoc cref="KeyedHashAlgorithm.Create(string)" />
+    [Obsolete("Cryptographic factory methods accepting an algorithm name are obsolete. Use the parameterless Create factory method on the algorithm type instead.")]
+#if !NETSTANDARD2_0
+    [RequiresUnreferencedCode("The default algorithm implementations might be removed, use strong type references like 'RSA.Create()' instead.")]
+#endif
     public static new KeyedHashAlgorithm? Create(string algorithmName)
     {
-        return algorithmName != null ? algorithmName == nameof(AesCmac) ? Create() : null
-            : throw new ArgumentNullException(nameof(algorithmName));
+        return algorithmName == nameof(AesCmac) ? Create() : KeyedHashAlgorithm.Create(algorithmName);
     }
 
     /// <summary>

AesExtra/AesCtr.cs

@@ -2,6 +2,7 @@
 //
 // SPDX-License-Identifier: MIT
 
+using System.Diagnostics.CodeAnalysis;
 using System.Security.Cryptography;
 
 namespace Dorssel.Security.Cryptography;
@@ -25,10 +26,13 @@ public sealed class AesCtr
     }
 
     /// <inheritdoc cref="Aes.Create(string)" />
+    [Obsolete("Cryptographic factory methods accepting an algorithm name are obsolete. Use the parameterless Create factory method on the algorithm type instead.")]
+#if !NETSTANDARD2_0
+    [RequiresUnreferencedCode("The default algorithm implementations might be removed, use strong type references like 'RSA.Create()' instead.")]
+#endif
     public static new Aes? Create(string algorithmName)
     {
-        return algorithmName != null ? algorithmName == nameof(AesCtr) ? Create() : null
-            : throw new ArgumentNullException(nameof(algorithmName));
+        return algorithmName == nameof(AesCtr) ? Create() : Aes.Create(algorithmName);
     }
 
     AesCtr()

UnitTests/AesCmac_Tests.cs

@@ -17,7 +17,9 @@ public void Create()
     [TestMethod]
     public void Create_Name()
     {
+#pragma warning disable CS0618 // Type or member is obsolete
         using var keyedHashAlgorithm = AesCmac.Create("AesCmac");
+#pragma warning restore CS0618 // Type or member is obsolete
         Assert.IsNotNull(keyedHashAlgorithm);
     }
 
@@ -26,14 +28,18 @@ public void Create_NullNameFails()
     {
         Assert.ThrowsException<ArgumentNullException>(() =>
         {
+#pragma warning disable CS0618 // Type or member is obsolete
             using var keyedHashAlgorithm = AesCmac.Create(null!);
+#pragma warning restore CS0618 // Type or member is obsolete
         });
     }
 
     [TestMethod]
     public void Create_OtherNameReturnsNull()
     {
+#pragma warning disable CS0618 // Type or member is obsolete
         using var keyedHashAlgorithm = AesCmac.Create("SomeOtherName");
+#pragma warning restore CS0618 // Type or member is obsolete
         Assert.IsNull(keyedHashAlgorithm);
     }
 

UnitTests/AesCtr_Tests.cs

@@ -32,7 +32,9 @@ public void Create()
     [TestMethod]
     public void Create_Name()
     {
+#pragma warning disable CS0618 // Type or member is obsolete
         using var aes = AesCtr.Create("AesCtr");
+#pragma warning restore CS0618 // Type or member is obsolete
         Assert.IsNotNull(aes);
     }
 
@@ -41,14 +43,18 @@ public void Create_NullNameFails()
     {
         Assert.ThrowsException<ArgumentNullException>(() =>
         {
+#pragma warning disable CS0618 // Type or member is obsolete
             using var aes = AesCtr.Create(null!);
+#pragma warning restore CS0618 // Type or member is obsolete
         });
     }
 
     [TestMethod]
     public void Create_OtherNameReturnsNull()
     {
+#pragma warning disable CS0618 // Type or member is obsolete
         using var aes = AesCtr.Create("SomeOtherName");
+#pragma warning restore CS0618 // Type or member is obsolete
         Assert.IsNull(aes);
     }