Create interface for dist metadata cache options

src/Microsoft.IdentityModel.Protocols/Configuration/DistributedMetadataCacheOptions.cs

@@ -0,0 +1,19 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using Microsoft.Extensions.Caching.Distributed;
+
+namespace Microsoft.IdentityModel.Protocols.Configuration
+{
+    /// <summary>
+    /// Specifies the DistributedMetadataCacheOptions which can be used to configure the distributed metadata cache.
+    /// </summary>
+    public class DistributedMetadataCacheOptions
+    {
+        /// <inheritdoc/>
+        public IDistributedCache DistributedCache { get; set; }
+
+        /// <inheritdoc/>
+        public IByteArrayCacheTransformer ByteArrayCacheTransformer { get; set; }
+    }
+}

src/Microsoft.IdentityModel.Protocols/Configuration/IByteArrayCacheTransformer.cs

@@ -0,0 +1,25 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+namespace Microsoft.IdentityModel.Protocols.Configuration
+{
+    /// <summary>
+    /// Interface that defines methods to transform byte arrays before they are written to a cache and after they are retrieved from a cache.
+    /// </summary>
+    public interface IByteArrayCacheTransformer
+    {
+        /// <summary>
+        /// Transform the provided <see cref="byte"/> array before it is written to a cache.
+        /// </summary>
+        /// <param name="data">The <see cref="byte"/>s to be transformed.</param>
+        /// <returns>The result of the transformation.</returns>
+        byte[] TransformBeforeCaching(byte[] data);
+
+        /// <summary>
+        /// TRansform the provided <see cref="byte"/> array after it is retrieved from a cache.
+        /// </summary>
+        /// <param name="data">The <see cref="byte"/>s to be transformed.</param>
+        /// <returns>The result of the transformation.</returns>
+        byte[] TransformAfterRetrieval(byte[] data);
+    }
+}

src/Microsoft.IdentityModel.Protocols/Microsoft.IdentityModel.Protocols.csproj

@@ -20,6 +20,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
+    <PackageReference Include="Microsoft.Extensions.Caching.Abstractions" Version="8.0.0" />
   </ItemGroup>
 
   <ItemGroup>