init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Crypto/Modes/OfbBlockCipher.cs

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+using System;
+using Org.BouncyCastle.Crypto.Parameters;
+
+namespace Org.BouncyCastle.Crypto.Modes;
+
+public class OfbBlockCipher : IBlockCipher
+{
+	private byte[] IV;
+
+	private byte[] ofbV;
+
+	private byte[] ofbOutV;
+
+	private readonly int blockSize;
+
+	private readonly IBlockCipher cipher;
+
+	public string AlgorithmName => cipher.AlgorithmName + "/OFB" + blockSize * 8;
+
+	public bool IsPartialBlockOkay => true;
+
+	public OfbBlockCipher(IBlockCipher cipher, int blockSize)
+	{
+		this.cipher = cipher;
+		this.blockSize = blockSize / 8;
+		IV = new byte[cipher.GetBlockSize()];
+		ofbV = new byte[cipher.GetBlockSize()];
+		ofbOutV = new byte[cipher.GetBlockSize()];
+	}
+
+	public IBlockCipher GetUnderlyingCipher()
+	{
+		return cipher;
+	}
+
+	public void Init(bool forEncryption, ICipherParameters parameters)
+	{
+		if (parameters is ParametersWithIV)
+		{
+			ParametersWithIV parametersWithIV = (ParametersWithIV)parameters;
+			byte[] iV = parametersWithIV.GetIV();
+			if (iV.Length < IV.Length)
+			{
+				Array.Copy(iV, 0, IV, IV.Length - iV.Length, iV.Length);
+				for (int i = 0; i < IV.Length - iV.Length; i++)
+				{
+					IV[i] = 0;
+				}
+			}
+			else
+			{
+				Array.Copy(iV, 0, IV, 0, IV.Length);
+			}
+			parameters = parametersWithIV.Parameters;
+		}
+		Reset();
+		if (parameters != null)
+		{
+			cipher.Init(forEncryption: true, parameters);
+		}
+	}
+
+	public int GetBlockSize()
+	{
+		return blockSize;
+	}
+
+	public int ProcessBlock(byte[] input, int inOff, byte[] output, int outOff)
+	{
+		if (inOff + blockSize > input.Length)
+		{
+			throw new DataLengthException("input buffer too short");
+		}
+		if (outOff + blockSize > output.Length)
+		{
+			throw new DataLengthException("output buffer too short");
+		}
+		cipher.ProcessBlock(ofbV, 0, ofbOutV, 0);
+		for (int i = 0; i < blockSize; i++)
+		{
+			output[outOff + i] = (byte)(ofbOutV[i] ^ input[inOff + i]);
+		}
+		Array.Copy(ofbV, blockSize, ofbV, 0, ofbV.Length - blockSize);
+		Array.Copy(ofbOutV, 0, ofbV, ofbV.Length - blockSize, blockSize);
+		return blockSize;
+	}
+
+	public void Reset()
+	{
+		Array.Copy(IV, 0, ofbV, 0, IV.Length);
+		cipher.Reset();
+	}
+}