part #2

src/__Libraries/StellaOps.Cryptography.Kms/FileKmsClient.Verification.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace StellaOps.Cryptography.Kms;
+
+public sealed partial class FileKmsClient
+{
+    public async Task<bool> VerifyAsync(
+        string keyId,
+        string? keyVersion,
+        ReadOnlyMemory<byte> data,
+        ReadOnlyMemory<byte> signature,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(keyId);
+        if (data.IsEmpty || signature.IsEmpty)
+        {
+            return false;
+        }
+
+        await _mutex.WaitAsync(cancellationToken).ConfigureAwait(false);
+        try
+        {
+            var record = await LoadOrCreateMetadataAsync(keyId, cancellationToken, createIfMissing: false).ConfigureAwait(false);
+            if (record is null)
+            {
+                return false;
+            }
+
+            var version = ResolveVersion(record, keyVersion);
+            if (string.IsNullOrWhiteSpace(version.PublicKey))
+            {
+                return false;
+            }
+
+            return VerifyData(version.CurveName, version.PublicKey, data.Span, signature.Span);
+        }
+        finally
+        {
+            _mutex.Release();
+        }
+    }
+}