Add more MD5 methods and Compute136

Src/GBX.NET.Crypto/MD5.cs

@@ -14,6 +14,18 @@ public static byte[] Compute(byte[] data)
 #endif
     }
 
+#if NET6_0_OR_GREATER
+    public static byte[] Compute(Span<byte> data)
+    {
+        return System.Security.Cryptography.MD5.HashData(data);
+    }
+
+    public static int Compute(Span<byte> data, Span<byte> destination)
+    {
+        return System.Security.Cryptography.MD5.HashData(data, destination);
+    }
+#endif
+
     public static byte[] Compute(string data)
     {
         return Compute(Encoding.ASCII.GetBytes(data));
@@ -42,4 +54,56 @@ public static async Task<byte[]> ComputeAsync(string data, CancellationToken can
     {
         return await ComputeAsync(Encoding.ASCII.GetBytes(data), cancellationToken);
     }
+
+    public static string Compute136(string text)
+    {
+#if NET6_0_OR_GREATER
+        var charSpan = text.AsSpan();
+        Span<char> loweredCharSpan = stackalloc char[text.Length];
+        if (charSpan.ToLowerInvariant(loweredCharSpan) != text.Length)
+        {
+            loweredCharSpan = text.ToLowerInvariant().ToArray();
+        }
+        Span<byte> bytes = stackalloc byte[text.Length * 2];
+        if (Encoding.UTF8.GetBytes(loweredCharSpan, bytes) != bytes.Length)
+        {
+            bytes = Encoding.UTF8.GetBytes(text.ToLowerInvariant());
+        }
+        Span<byte> hash = stackalloc byte[17];
+        if (Compute(bytes, hash.Slice(1)) != 16)
+        {
+            throw new InvalidOperationException();
+        }
+#else
+        var lowered = text.ToLower();
+        var bytes = Encoding.UTF8.GetBytes(lowered);
+        var hashWithoutLength = Compute(bytes);
+        var hash = new byte[17];
+        Buffer.BlockCopy(hashWithoutLength, 0, hash, 1, hashWithoutLength.Length);
+#endif
+        hash[0] = (byte)bytes.Length;
+
+        return ToHex(hash).ToString();
+    }
+
+    private static Span<char> ToHex(Span<byte> value)
+    {
+        var str = new char[value.Length * 2];
+
+        for (var i = 0; i < value.Length; i++)
+        {
+            var hex1 = HexIntToChar((byte)(value[i] % 16));
+            var hex2 = HexIntToChar((byte)(value[i] / 16));
+
+            str[i * 2] = hex1;
+            str[i * 2 + 1] = hex2;
+        }
+
+        return str;
+    }
+
+    private static char HexIntToChar(byte v)
+    {
+        return v < 10 ? (char)(v + 48) : (char)(v + 55);
+    }
 }