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/*
KeePass Password Safe - The Open-Source Password Manager
Copyright (C) 2003-2019 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.Diagnostics;
using System.Text;
#if !KeePassUAP
using System.Security.Cryptography;
#endif
using KeePassLib.Security;
using KeePassLib.Utility;
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");
PwgError e = PwgError.Unknown;
CryptoRandomStream crs = null;
byte[] pbKey = null;
try
{
crs = CreateRandomStream(pbUserEntropy, out pbKey);
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; }
}
finally
{
if(crs != null) crs.Dispose();
if(pbKey != null) MemUtil.ZeroByteArray(pbKey);
}
return e;
}
private static CryptoRandomStream CreateRandomStream(byte[] pbAdditionalEntropy,
out byte[] pbKey)
{
pbKey = CryptoRandom.Instance.GetRandomBytes(128);
// Mix in additional entropy
Debug.Assert(pbKey.Length >= 64);
if((pbAdditionalEntropy != null) && (pbAdditionalEntropy.Length > 0))
{
using(SHA512Managed h = new SHA512Managed())
{
byte[] pbHash = h.ComputeHash(pbAdditionalEntropy);
MemUtil.XorArray(pbHash, 0, pbKey, 0, pbHash.Length);
}
}
return new CryptoRandomStream(CrsAlgorithm.ChaCha20, 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 Shuffle(char[] v, CryptoRandomStream crsRandomSource)
{
if(v == null) { Debug.Assert(false); return; }
if(crsRandomSource == null) { Debug.Assert(false); return; }
for(int i = v.Length - 1; i >= 1; --i)
{
ulong r = crsRandomSource.GetRandomUInt64();
int j = (int)(r % (ulong)(i + 1));
char t = v[i];
v[i] = v[j];
v[j] = t;
}
}
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)) 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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