init commit

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

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+using System;
+using Org.BouncyCastle.Crypto.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Engines;
+
+public class ChaChaEngine : Salsa20Engine
+{
+	public override string AlgorithmName => "ChaCha" + rounds;
+
+	public ChaChaEngine()
+	{
+	}
+
+	public ChaChaEngine(int rounds)
+		: base(rounds)
+	{
+	}
+
+	protected override void AdvanceCounter()
+	{
+		uint[] array;
+		if (((array = engineState)[12] = array[12] + 1) == 0)
+		{
+			(array = engineState)[13] = array[13] + 1;
+		}
+	}
+
+	protected override void ResetCounter()
+	{
+		engineState[12] = (engineState[13] = 0u);
+	}
+
+	protected override void SetKey(byte[] keyBytes, byte[] ivBytes)
+	{
+		if (keyBytes != null)
+		{
+			if (keyBytes.Length != 16 && keyBytes.Length != 32)
+			{
+				throw new ArgumentException(AlgorithmName + " requires 128 bit or 256 bit key");
+			}
+			PackTauOrSigma(keyBytes.Length, engineState, 0);
+			Pack.LE_To_UInt32(keyBytes, 0, engineState, 4, 4);
+			Pack.LE_To_UInt32(keyBytes, keyBytes.Length - 16, engineState, 8, 4);
+		}
+		Pack.LE_To_UInt32(ivBytes, 0, engineState, 14, 2);
+	}
+
+	protected override void GenerateKeyStream(byte[] output)
+	{
+		ChachaCore(rounds, engineState, x);
+		Pack.UInt32_To_LE(x, output, 0);
+	}
+
+	internal static void ChachaCore(int rounds, uint[] input, uint[] x)
+	{
+		if (input.Length != 16)
+		{
+			throw new ArgumentException();
+		}
+		if (x.Length != 16)
+		{
+			throw new ArgumentException();
+		}
+		if (rounds % 2 != 0)
+		{
+			throw new ArgumentException("Number of rounds must be even");
+		}
+		uint num = input[0];
+		uint num2 = input[1];
+		uint num3 = input[2];
+		uint num4 = input[3];
+		uint num5 = input[4];
+		uint num6 = input[5];
+		uint num7 = input[6];
+		uint num8 = input[7];
+		uint num9 = input[8];
+		uint num10 = input[9];
+		uint num11 = input[10];
+		uint num12 = input[11];
+		uint num13 = input[12];
+		uint num14 = input[13];
+		uint num15 = input[14];
+		uint num16 = input[15];
+		for (int num17 = rounds; num17 > 0; num17 -= 2)
+		{
+			num += num5;
+			num13 = Salsa20Engine.R(num13 ^ num, 16);
+			num9 += num13;
+			num5 = Salsa20Engine.R(num5 ^ num9, 12);
+			num += num5;
+			num13 = Salsa20Engine.R(num13 ^ num, 8);
+			num9 += num13;
+			num5 = Salsa20Engine.R(num5 ^ num9, 7);
+			num2 += num6;
+			num14 = Salsa20Engine.R(num14 ^ num2, 16);
+			num10 += num14;
+			num6 = Salsa20Engine.R(num6 ^ num10, 12);
+			num2 += num6;
+			num14 = Salsa20Engine.R(num14 ^ num2, 8);
+			num10 += num14;
+			num6 = Salsa20Engine.R(num6 ^ num10, 7);
+			num3 += num7;
+			num15 = Salsa20Engine.R(num15 ^ num3, 16);
+			num11 += num15;
+			num7 = Salsa20Engine.R(num7 ^ num11, 12);
+			num3 += num7;
+			num15 = Salsa20Engine.R(num15 ^ num3, 8);
+			num11 += num15;
+			num7 = Salsa20Engine.R(num7 ^ num11, 7);
+			num4 += num8;
+			num16 = Salsa20Engine.R(num16 ^ num4, 16);
+			num12 += num16;
+			num8 = Salsa20Engine.R(num8 ^ num12, 12);
+			num4 += num8;
+			num16 = Salsa20Engine.R(num16 ^ num4, 8);
+			num12 += num16;
+			num8 = Salsa20Engine.R(num8 ^ num12, 7);
+			num += num6;
+			num16 = Salsa20Engine.R(num16 ^ num, 16);
+			num11 += num16;
+			num6 = Salsa20Engine.R(num6 ^ num11, 12);
+			num += num6;
+			num16 = Salsa20Engine.R(num16 ^ num, 8);
+			num11 += num16;
+			num6 = Salsa20Engine.R(num6 ^ num11, 7);
+			num2 += num7;
+			num13 = Salsa20Engine.R(num13 ^ num2, 16);
+			num12 += num13;
+			num7 = Salsa20Engine.R(num7 ^ num12, 12);
+			num2 += num7;
+			num13 = Salsa20Engine.R(num13 ^ num2, 8);
+			num12 += num13;
+			num7 = Salsa20Engine.R(num7 ^ num12, 7);
+			num3 += num8;
+			num14 = Salsa20Engine.R(num14 ^ num3, 16);
+			num9 += num14;
+			num8 = Salsa20Engine.R(num8 ^ num9, 12);
+			num3 += num8;
+			num14 = Salsa20Engine.R(num14 ^ num3, 8);
+			num9 += num14;
+			num8 = Salsa20Engine.R(num8 ^ num9, 7);
+			num4 += num5;
+			num15 = Salsa20Engine.R(num15 ^ num4, 16);
+			num10 += num15;
+			num5 = Salsa20Engine.R(num5 ^ num10, 12);
+			num4 += num5;
+			num15 = Salsa20Engine.R(num15 ^ num4, 8);
+			num10 += num15;
+			num5 = Salsa20Engine.R(num5 ^ num10, 7);
+		}
+		x[0] = num + input[0];
+		x[1] = num2 + input[1];
+		x[2] = num3 + input[2];
+		x[3] = num4 + input[3];
+		x[4] = num5 + input[4];
+		x[5] = num6 + input[5];
+		x[6] = num7 + input[6];
+		x[7] = num8 + input[7];
+		x[8] = num9 + input[8];
+		x[9] = num10 + input[9];
+		x[10] = num11 + input[10];
+		x[11] = num12 + input[11];
+		x[12] = num13 + input[12];
+		x[13] = num14 + input[13];
+		x[14] = num15 + input[14];
+		x[15] = num16 + input[15];
+	}
+}