init commit

output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Crypto/Engines/ChaCha7539Engine.cs

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+using System;
+using Org.BouncyCastle.Crypto.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Engines;
+
+public class ChaCha7539Engine : Salsa20Engine
+{
+	public override string AlgorithmName => "ChaCha7539" + rounds;
+
+	protected override int NonceSize => 12;
+
+	protected override void AdvanceCounter()
+	{
+		uint[] array;
+		if (((array = engineState)[12] = array[12] + 1) == 0)
+		{
+			throw new InvalidOperationException("attempt to increase counter past 2^32.");
+		}
+	}
+
+	protected override void ResetCounter()
+	{
+		engineState[12] = 0u;
+	}
+
+	protected override void SetKey(byte[] keyBytes, byte[] ivBytes)
+	{
+		if (keyBytes != null)
+		{
+			if (keyBytes.Length != 32)
+			{
+				throw new ArgumentException(AlgorithmName + " requires 256 bit key");
+			}
+			PackTauOrSigma(keyBytes.Length, engineState, 0);
+			Pack.LE_To_UInt32(keyBytes, 0, engineState, 4, 8);
+		}
+		Pack.LE_To_UInt32(ivBytes, 0, engineState, 13, 3);
+	}
+
+	protected override void GenerateKeyStream(byte[] output)
+	{
+		ChaChaEngine.ChachaCore(rounds, engineState, x);
+		Pack.UInt32_To_LE(x, output, 0);
+	}
+}