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src/__Libraries/StellaOps.Facet/DefaultCryptoHash.cs

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+// <copyright file="DefaultCryptoHash.cs" company="StellaOps">
+// Copyright (c) StellaOps. Licensed under AGPL-3.0-or-later.
+// </copyright>
+
+using System.Security.Cryptography;
+
+namespace StellaOps.Facet;
+
+/// <summary>
+/// Default implementation of <see cref="ICryptoHash"/> using .NET built-in algorithms.
+/// </summary>
+public sealed class DefaultCryptoHash : ICryptoHash
+{
+    /// <summary>
+    /// Gets the singleton instance.
+    /// </summary>
+    public static DefaultCryptoHash Instance { get; } = new();
+
+    /// <inheritdoc/>
+    public byte[] ComputeHash(byte[] data, string algorithm)
+    {
+        ArgumentNullException.ThrowIfNull(data);
+        ArgumentException.ThrowIfNullOrWhiteSpace(algorithm);
+
+        return algorithm.ToUpperInvariant() switch
+        {
+            "SHA256" => SHA256.HashData(data),
+            "SHA384" => SHA384.HashData(data),
+            "SHA512" => SHA512.HashData(data),
+            "SHA1" => SHA1.HashData(data),
+            "MD5" => MD5.HashData(data),
+            _ => throw new NotSupportedException($"Hash algorithm '{algorithm}' is not supported")
+        };
+    }
+
+    /// <inheritdoc/>
+    public async Task<byte[]> ComputeHashAsync(
+        Stream stream,
+        string algorithm,
+        CancellationToken ct = default)
+    {
+        ArgumentNullException.ThrowIfNull(stream);
+        ArgumentException.ThrowIfNullOrWhiteSpace(algorithm);
+
+        return algorithm.ToUpperInvariant() switch
+        {
+            "SHA256" => await SHA256.HashDataAsync(stream, ct).ConfigureAwait(false),
+            "SHA384" => await SHA384.HashDataAsync(stream, ct).ConfigureAwait(false),
+            "SHA512" => await SHA512.HashDataAsync(stream, ct).ConfigureAwait(false),
+            _ => throw new NotSupportedException($"Hash algorithm '{algorithm}' is not supported for async")
+        };
+    }
+}