init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Crypto/Macs/GMac.cs

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+using System;
+using Org.BouncyCastle.Crypto.Modes;
+using Org.BouncyCastle.Crypto.Parameters;
+
+namespace Org.BouncyCastle.Crypto.Macs;
+
+public class GMac : IMac
+{
+	private readonly GcmBlockCipher cipher;
+
+	private readonly int macSizeBits;
+
+	public string AlgorithmName => cipher.GetUnderlyingCipher().AlgorithmName + "-GMAC";
+
+	public GMac(GcmBlockCipher cipher)
+		: this(cipher, 128)
+	{
+	}
+
+	public GMac(GcmBlockCipher cipher, int macSizeBits)
+	{
+		this.cipher = cipher;
+		this.macSizeBits = macSizeBits;
+	}
+
+	public void Init(ICipherParameters parameters)
+	{
+		if (parameters is ParametersWithIV)
+		{
+			ParametersWithIV parametersWithIV = (ParametersWithIV)parameters;
+			byte[] iV = parametersWithIV.GetIV();
+			KeyParameter key = (KeyParameter)parametersWithIV.Parameters;
+			cipher.Init(forEncryption: true, new AeadParameters(key, macSizeBits, iV));
+			return;
+		}
+		throw new ArgumentException("GMAC requires ParametersWithIV");
+	}
+
+	public int GetMacSize()
+	{
+		return macSizeBits / 8;
+	}
+
+	public void Update(byte input)
+	{
+		cipher.ProcessAadByte(input);
+	}
+
+	public void BlockUpdate(byte[] input, int inOff, int len)
+	{
+		cipher.ProcessAadBytes(input, inOff, len);
+	}
+
+	public int DoFinal(byte[] output, int outOff)
+	{
+		try
+		{
+			return cipher.DoFinal(output, outOff);
+		}
+		catch (InvalidCipherTextException ex)
+		{
+			throw new InvalidOperationException(ex.ToString());
+		}
+	}
+
+	public void Reset()
+	{
+		cipher.Reset();
+	}
+}