WIP - Implementing HMAC with BouncyCastle

ModernKeePassLib/Cryptography/Hash/HMACSHA256.cs

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+using System;
+using Org.BouncyCastle.Crypto.Digests;
+using Org.BouncyCastle.Crypto.Macs;
+using Org.BouncyCastle.Crypto.Parameters;
+
+namespace ModernKeePassLib.Cryptography.Hash
+{
+    public class HMACSHA256: IDisposable
+
+    {
+    private readonly HMac _hmac;
+
+    public HMACSHA256(byte[] key)
+    {
+        _hmac = new HMac(new Sha256Digest());
+        _hmac.Init(new KeyParameter(key));
+    }
+
+    public byte[] ComputeHash(byte[] value)
+    {
+        if (value == null) throw new ArgumentNullException("value");
+
+        byte[] resBuf = new byte[_hmac.GetMacSize()];
+        _hmac.BlockUpdate(value, 0, value.Length);
+        _hmac.DoFinal(resBuf, 0);
+
+        return resBuf;
+    }
+
+        public void Dispose()
+        {
+            _hmac.Reset();
+        }
+    }
+}