using Org.BouncyCastle.Crypto.Utilities; using System; namespace Org.BouncyCastle.Crypto.Engines { public class XSalsa20Engine : Salsa20Engine { public override string AlgorithmName => "XSalsa20"; protected override int NonceSize => 24; protected override void SetKey(byte[] keyBytes, byte[] ivBytes) { if (keyBytes == null) throw new ArgumentException(AlgorithmName + " doesn't support re-init with null key"); if (keyBytes.Length != 32) throw new ArgumentException(AlgorithmName + " requires a 256 bit key"); base.SetKey(keyBytes, ivBytes); Pack.LE_To_UInt32(ivBytes, 8, engineState, 8, 2); uint[] array = new uint[engineState.Length]; Salsa20Engine.SalsaCore(20, engineState, array); engineState[1] = array[0] - engineState[0]; engineState[2] = array[5] - engineState[5]; engineState[3] = array[10] - engineState[10]; engineState[4] = array[15] - engineState[15]; engineState[11] = array[6] - engineState[6]; engineState[12] = array[7] - engineState[7]; engineState[13] = array[8] - engineState[8]; engineState[14] = array[9] - engineState[9]; Pack.LE_To_UInt32(ivBytes, 16, engineState, 6, 2); } } }