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/*
KeePass Password Safe - The Open-Source Password Manager
Copyright (C) 2003-2012 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
*/
using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using KeePassLib.Security;
namespace KeePassLib.Cryptography.PasswordGenerator
{
public enum PwgError
{
Success = 0,
Unknown = 1,
TooFewCharacters = 2,
UnknownAlgorithm = 3
}
/// <summary>
/// Utility functions for generating random passwords.
/// </summary>
public static class PwGenerator
{
public static PwgError Generate(out ProtectedString psOut,
PwProfile pwProfile, byte[] pbUserEntropy,
CustomPwGeneratorPool pwAlgorithmPool)
{
Debug.Assert(pwProfile != null);
if(pwProfile == null) throw new ArgumentNullException("pwProfile");
CryptoRandomStream crs = CreateCryptoStream(pbUserEntropy);
PwgError e = PwgError.Unknown;
if(pwProfile.GeneratorType == PasswordGeneratorType.CharSet)
e = CharSetBasedGenerator.Generate(out psOut, pwProfile, crs);
else if(pwProfile.GeneratorType == PasswordGeneratorType.Pattern)
e = PatternBasedGenerator.Generate(out psOut, pwProfile, crs);
else if(pwProfile.GeneratorType == PasswordGeneratorType.Custom)
e = GenerateCustom(out psOut, pwProfile, crs, pwAlgorithmPool);
else { Debug.Assert(false); psOut = ProtectedString.Empty; }
return e;
}
private static CryptoRandomStream CreateCryptoStream(byte[] pbAdditionalEntropy)
{
byte[] pbKey = CryptoRandom.Instance.GetRandomBytes(256);
// Mix in additional entropy
if((pbAdditionalEntropy != null) && (pbAdditionalEntropy.Length > 0))
{
for(int nKeyPos = 0; nKeyPos < pbKey.Length; ++nKeyPos)
pbKey[nKeyPos] ^= pbAdditionalEntropy[nKeyPos % pbAdditionalEntropy.Length];
}
return new CryptoRandomStream(CrsAlgorithm.Salsa20, pbKey);
}
internal static char GenerateCharacter(PwProfile pwProfile,
PwCharSet pwCharSet, CryptoRandomStream crsRandomSource)
{
if(pwCharSet.Size == 0) return char.MinValue;
ulong uIndex = crsRandomSource.GetRandomUInt64();
uIndex %= (ulong)pwCharSet.Size;
char ch = pwCharSet[(uint)uIndex];
if(pwProfile.NoRepeatingCharacters)
pwCharSet.Remove(ch);
return ch;
}
internal static void PrepareCharSet(PwCharSet pwCharSet, PwProfile pwProfile)
{
pwCharSet.Remove(PwCharSet.Invalid);
if(pwProfile.ExcludeLookAlike) pwCharSet.Remove(PwCharSet.LookAlike);
if(pwProfile.ExcludeCharacters.Length > 0)
pwCharSet.Remove(pwProfile.ExcludeCharacters);
}
internal static void ShufflePassword(char[] pPassword,
CryptoRandomStream crsRandomSource)
{
Debug.Assert(pPassword != null); if(pPassword == null) return;
Debug.Assert(crsRandomSource != null); if(crsRandomSource == null) return;
if(pPassword.Length <= 1) return; // Nothing to shuffle
for(int nSelect = 0; nSelect < pPassword.Length; ++nSelect)
{
ulong uRandomIndex = crsRandomSource.GetRandomUInt64();
uRandomIndex %= (ulong)(pPassword.Length - nSelect);
char chTemp = pPassword[nSelect];
pPassword[nSelect] = pPassword[nSelect + (int)uRandomIndex];
pPassword[nSelect + (int)uRandomIndex] = chTemp;
}
}
private static PwgError GenerateCustom(out ProtectedString psOut,
PwProfile pwProfile, CryptoRandomStream crs,
CustomPwGeneratorPool pwAlgorithmPool)
{
psOut = ProtectedString.Empty;
Debug.Assert(pwProfile.GeneratorType == PasswordGeneratorType.Custom);
if(pwAlgorithmPool == null) return PwgError.UnknownAlgorithm;
string strID = pwProfile.CustomAlgorithmUuid;
if(string.IsNullOrEmpty(strID)) { Debug.Assert(false); return PwgError.UnknownAlgorithm; }
byte[] pbUuid = Convert.FromBase64String(strID);
PwUuid uuid = new PwUuid(pbUuid);
CustomPwGenerator pwg = pwAlgorithmPool.Find(uuid);
if(pwg == null) { Debug.Assert(false); return PwgError.UnknownAlgorithm; }
ProtectedString pwd = pwg.Generate(pwProfile.CloneDeep(), crs);
if(pwd == null) return PwgError.Unknown;
psOut = pwd;
return PwgError.Success;
}
}
}
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