part #2

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

@@ -0,0 +1,25 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace StellaOps.Cryptography.Kms;
+
+public sealed partial class Fido2KmsClient
+{
+    public async Task<KmsKeyMaterial> ExportAsync(string keyId, string? keyVersion, CancellationToken cancellationToken = default)
+    {
+        ThrowIfDisposed();
+
+        var metadata = await GetMetadataAsync(keyId, cancellationToken).ConfigureAwait(false);
+
+        return new KmsKeyMaterial(
+            metadata.KeyId,
+            metadata.KeyId,
+            metadata.Algorithm,
+            _curveName,
+            Array.Empty<byte>(),
+            _publicParameters.Q.X ?? throw new InvalidOperationException("FIDO2 public key missing X coordinate."),
+            _publicParameters.Q.Y ?? throw new InvalidOperationException("FIDO2 public key missing Y coordinate."),
+            _options.CreatedAt ?? _timeProvider.GetUtcNow());
+    }
+}