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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
*/
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;
using KeePassLib.Security;
using KeePassLib.Utility;
namespace KeePassLib.Cryptography.PasswordGenerator
{
internal static class PatternBasedGenerator
{
internal static PwgError Generate(out ProtectedString psOut,
PwProfile pwProfile, CryptoRandomStream crsRandomSource)
{
psOut = ProtectedString.Empty;
string strPattern = pwProfile.Pattern;
if(string.IsNullOrEmpty(strPattern)) return PwgError.Success;
CharStream cs = new CharStream(strPattern);
LinkedList<char> llGenerated = new LinkedList<char>();
PwCharSet pcs = new PwCharSet();
while(true)
{
char ch = cs.ReadChar();
if(ch == char.MinValue) break;
pcs.Clear();
if(ch == '\\')
{
ch = cs.ReadChar();
if(ch == char.MinValue) return PwgError.InvalidPattern;
pcs.Add(ch); // Allow "{...}" support and char check
}
else if(ch == '[')
{
if(!ReadCustomCharSet(cs, pcs))
return PwgError.InvalidPattern;
}
else
{
if(!pcs.AddCharSet(ch))
return PwgError.InvalidPattern;
}
int nCount = 1;
if(cs.PeekChar() == '{')
{
nCount = ReadCount(cs);
if(nCount < 0) return PwgError.InvalidPattern;
}
for(int i = 0; i < nCount; ++i)
{
if(!PwGenerator.PrepareCharSet(pcs, pwProfile))
return PwgError.InvalidCharSet;
if(pwProfile.NoRepeatingCharacters)
{
foreach(char chUsed in llGenerated)
pcs.Remove(chUsed);
}
char chGen = PwGenerator.GenerateCharacter(pcs,
crsRandomSource);
if(chGen == char.MinValue) return PwgError.TooFewCharacters;
llGenerated.AddLast(chGen);
}
}
if(llGenerated.Count == 0) return PwgError.Success;
char[] v = new char[llGenerated.Count];
llGenerated.CopyTo(v, 0);
if(pwProfile.PatternPermutePassword)
PwGenerator.Shuffle(v, crsRandomSource);
byte[] pbUtf8 = StrUtil.Utf8.GetBytes(v);
psOut = new ProtectedString(true, pbUtf8);
MemUtil.ZeroByteArray(pbUtf8);
MemUtil.ZeroArray<char>(v);
return PwgError.Success;
}
private static bool ReadCustomCharSet(CharStream cs, PwCharSet pcsOut)
{
Debug.Assert(cs.PeekChar() != '['); // Consumed already
Debug.Assert(pcsOut.Size == 0);
bool bAdd = true;
while(true)
{
char ch = cs.ReadChar();
if(ch == char.MinValue) return false;
if(ch == ']') break;
if(ch == '\\')
{
ch = cs.ReadChar();
if(ch == char.MinValue) return false;
if(bAdd) pcsOut.Add(ch);
else pcsOut.Remove(ch);
}
else if(ch == '^')
{
if(bAdd) bAdd = false;
else return false; // '^' toggles the mode only once
}
else
{
PwCharSet pcs = new PwCharSet();
if(!pcs.AddCharSet(ch)) return false;
if(bAdd) pcsOut.Add(pcs.ToString());
else pcsOut.Remove(pcs.ToString());
}
}
return true;
}
private static int ReadCount(CharStream cs)
{
if(cs.ReadChar() != '{') { Debug.Assert(false); return -1; }
// Ensure not empty
char chFirst = cs.PeekChar();
if((chFirst < '0') || (chFirst > '9')) return -1;
long n = 0;
while(true)
{
char ch = cs.ReadChar();
if(ch == '}') break;
if((ch >= '0') && (ch <= '9'))
{
n = (n * 10L) + (long)(ch - '0');
if(n > int.MaxValue) return -1;
}
else return -1;
}
return (int)n;
}
}
}
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