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/*
KeePass Password Safe - The Open-Source Password Manager
Copyright (C) 2003-2024 Dominik Reichl <dominik.reichl@t-online.de>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
// Implementation of the Salsa20 cipher, based on the eSTREAM
// submission by D. J. Bernstein.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using KeePassLib.Utility;
namespace KeePassLib.Cryptography.Cipher
{
public sealed class Salsa20Cipher : CtrBlockCipher
{
private readonly uint[] m_s = new uint[16]; // State
private readonly uint[] m_x = new uint[16]; // Working buffer
public override int BlockSize
{
get { return 64; }
}
public Salsa20Cipher(byte[] pbKey32, byte[] pbIV8) : base()
{
if(pbKey32 == null) throw new ArgumentNullException("pbKey32");
if(pbKey32.Length != 32) throw new ArgumentOutOfRangeException("pbKey32");
if(pbIV8 == null) throw new ArgumentNullException("pbIV8");
if(pbIV8.Length != 8) throw new ArgumentOutOfRangeException("pbIV8");
m_s[0] = 0x61707865;
m_s[5] = 0x3320646E;
m_s[10] = 0x79622D32;
m_s[15] = 0x6B206574;
m_s[1] = MemUtil.BytesToUInt32(pbKey32, 0);
m_s[2] = MemUtil.BytesToUInt32(pbKey32, 4);
m_s[3] = MemUtil.BytesToUInt32(pbKey32, 8);
m_s[4] = MemUtil.BytesToUInt32(pbKey32, 12);
m_s[11] = MemUtil.BytesToUInt32(pbKey32, 16);
m_s[12] = MemUtil.BytesToUInt32(pbKey32, 20);
m_s[13] = MemUtil.BytesToUInt32(pbKey32, 24);
m_s[14] = MemUtil.BytesToUInt32(pbKey32, 28);
m_s[6] = MemUtil.BytesToUInt32(pbIV8, 0);
m_s[7] = MemUtil.BytesToUInt32(pbIV8, 4);
m_s[8] = 0; // Counter, low
m_s[9] = 0; // Counter, high
}
protected override void Dispose(bool bDisposing)
{
if(bDisposing)
{
MemUtil.ZeroArray<uint>(m_s);
MemUtil.ZeroArray<uint>(m_x);
}
base.Dispose(bDisposing);
}
protected override void NextBlock(byte[] pbBlock)
{
if(pbBlock == null) throw new ArgumentNullException("pbBlock");
if(pbBlock.Length != 64) throw new ArgumentOutOfRangeException("pbBlock");
// x is a local alias for the working buffer; with this,
// the compiler/runtime might remove some checks
uint[] x = m_x;
if(x == null) throw new InvalidOperationException();
if(x.Length < 16) throw new InvalidOperationException();
uint[] s = m_s;
if(s == null) throw new InvalidOperationException();
if(s.Length < 16) throw new InvalidOperationException();
Array.Copy(s, x, 16);
unchecked
{
// 10 * 8 quarter rounds = 20 rounds
for(int i = 0; i < 10; ++i)
{
x[ 4] ^= MemUtil.RotateLeft32(x[ 0] + x[12], 7);
x[ 8] ^= MemUtil.RotateLeft32(x[ 4] + x[ 0], 9);
x[12] ^= MemUtil.RotateLeft32(x[ 8] + x[ 4], 13);
x[ 0] ^= MemUtil.RotateLeft32(x[12] + x[ 8], 18);
x[ 9] ^= MemUtil.RotateLeft32(x[ 5] + x[ 1], 7);
x[13] ^= MemUtil.RotateLeft32(x[ 9] + x[ 5], 9);
x[ 1] ^= MemUtil.RotateLeft32(x[13] + x[ 9], 13);
x[ 5] ^= MemUtil.RotateLeft32(x[ 1] + x[13], 18);
x[14] ^= MemUtil.RotateLeft32(x[10] + x[ 6], 7);
x[ 2] ^= MemUtil.RotateLeft32(x[14] + x[10], 9);
x[ 6] ^= MemUtil.RotateLeft32(x[ 2] + x[14], 13);
x[10] ^= MemUtil.RotateLeft32(x[ 6] + x[ 2], 18);
x[ 3] ^= MemUtil.RotateLeft32(x[15] + x[11], 7);
x[ 7] ^= MemUtil.RotateLeft32(x[ 3] + x[15], 9);
x[11] ^= MemUtil.RotateLeft32(x[ 7] + x[ 3], 13);
x[15] ^= MemUtil.RotateLeft32(x[11] + x[ 7], 18);
x[ 1] ^= MemUtil.RotateLeft32(x[ 0] + x[ 3], 7);
x[ 2] ^= MemUtil.RotateLeft32(x[ 1] + x[ 0], 9);
x[ 3] ^= MemUtil.RotateLeft32(x[ 2] + x[ 1], 13);
x[ 0] ^= MemUtil.RotateLeft32(x[ 3] + x[ 2], 18);
x[ 6] ^= MemUtil.RotateLeft32(x[ 5] + x[ 4], 7);
x[ 7] ^= MemUtil.RotateLeft32(x[ 6] + x[ 5], 9);
x[ 4] ^= MemUtil.RotateLeft32(x[ 7] + x[ 6], 13);
x[ 5] ^= MemUtil.RotateLeft32(x[ 4] + x[ 7], 18);
x[11] ^= MemUtil.RotateLeft32(x[10] + x[ 9], 7);
x[ 8] ^= MemUtil.RotateLeft32(x[11] + x[10], 9);
x[ 9] ^= MemUtil.RotateLeft32(x[ 8] + x[11], 13);
x[10] ^= MemUtil.RotateLeft32(x[ 9] + x[ 8], 18);
x[12] ^= MemUtil.RotateLeft32(x[15] + x[14], 7);
x[13] ^= MemUtil.RotateLeft32(x[12] + x[15], 9);
x[14] ^= MemUtil.RotateLeft32(x[13] + x[12], 13);
x[15] ^= MemUtil.RotateLeft32(x[14] + x[13], 18);
}
for(int i = 0; i < 16; ++i) x[i] += s[i];
for(int i = 0; i < 16; ++i)
{
int i4 = i << 2;
uint xi = x[i];
pbBlock[i4] = (byte)xi;
pbBlock[i4 + 1] = (byte)(xi >> 8);
pbBlock[i4 + 2] = (byte)(xi >> 16);
pbBlock[i4 + 3] = (byte)(xi >> 24);
}
++s[8];
if(s[8] == 0) ++s[9];
}
}
}
}
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