part #2

src/__Libraries/StellaOps.Cryptography.Kms/Fido2KmsClient.Metadata.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace StellaOps.Cryptography.Kms;
+
+public sealed partial class Fido2KmsClient
+{
+    public Task<KmsKeyMetadata> GetMetadataAsync(string keyId, CancellationToken cancellationToken = default)
+    {
+        ThrowIfDisposed();
+
+        var now = _timeProvider.GetUtcNow();
+        if (_cachedMetadata is not null && _metadataExpiresAt > now)
+        {
+            return Task.FromResult(_cachedMetadata);
+        }
+
+        var createdAt = _options.CreatedAt ?? _timeProvider.GetUtcNow();
+        var version = new KmsKeyVersionMetadata(
+            _options.CredentialId,
+            KmsKeyState.Active,
+            createdAt,
+            null,
+            Convert.ToBase64String(_subjectPublicKeyInfo),
+            _curveName);
+
+        _cachedMetadata = new KmsKeyMetadata(
+            _options.CredentialId,
+            KmsAlgorithms.Es256,
+            KmsKeyState.Active,
+            createdAt,
+            ImmutableArray.Create(version));
+
+        _metadataExpiresAt = now.Add(_metadataCacheDuration);
+        return Task.FromResult(_cachedMetadata);
+    }
+}