private static bool EvalAddPopularPasswordPattern(List <QePatternInstance>[] vPatterns,
char[] vPassword, int i, char[] vSub, double dblCostPerMod)
{
ulong uDictSize;
if (!PopularPasswords.IsPopularPassword(vSub, out uDictSize))
{
return(false);
}
int n = vSub.Length;
int d = HammingDist(vSub, 0, vPassword, i, n);
double dblCost = Log2((double)uDictSize);
// dblCost += log2(n binom d)
int k = Math.Min(d, n - d);
for (int j = n; j > (n - k); --j)
{
dblCost += Log2(j);
}
for (int j = k; j >= 2; --j)
{
dblCost -= Log2(j);
}
dblCost += dblCostPerMod * (double)d;
vPatterns[i].Add(new QePatternInstance(i, n, PatternID.Dictionary,
dblCost));
return(true);
}
/// <summary>
/// Estimate the quality of a password.
/// </summary>
/// <param name="vPasswordChars">Password to check.</param>
/// <returns>Estimated bit-strength of the password.</returns>
/// <exception cref="System.ArgumentNullException">Thrown if the input
/// parameter is <c>null</c>.</exception>
public static uint EstimatePasswordBits(char[] vPasswordChars)
{
Debug.Assert(vPasswordChars != null);
if (vPasswordChars == null)
{
throw new ArgumentNullException("vPasswordChars");
}
bool bChLower = false, bChUpper = false, bChNumber = false;
bool bChSpecial = false, bChHigh = false, bChControl = false;
Dictionary <char, uint> vCharCounts = new Dictionary <char, uint>();
Dictionary <int, uint> vDifferences = new Dictionary <int, uint>();
double dblEffectiveLength = 0.0;
for (int i = 0; i < vPasswordChars.Length; ++i) // Get character types
{
char tch = vPasswordChars[i];
if (tch < ' ')
{
bChControl = true;
}
else if ((tch >= 'A') && (tch <= 'Z'))
{
bChUpper = true;
}
else if ((tch >= 'a') && (tch <= 'z'))
{
bChLower = true;
}
else if ((tch >= '0') && (tch <= '9'))
{
bChNumber = true;
}
else if ((tch >= ' ') && (tch <= '/'))
{
bChSpecial = true;
}
else if ((tch >= ':') && (tch <= '@'))
{
bChSpecial = true;
}
else if ((tch >= '[') && (tch <= '`'))
{
bChSpecial = true;
}
else if ((tch >= '{') && (tch <= '~'))
{
bChSpecial = true;
}
else if (tch > '~')
{
bChHigh = true;
}
double dblDiffFactor = 1.0;
if (i >= 1)
{
int iDiff = (int)tch - (int)vPasswordChars[i - 1];
uint uDiffCount;
if (vDifferences.TryGetValue(iDiff, out uDiffCount))
{
++uDiffCount;
vDifferences[iDiff] = uDiffCount;
dblDiffFactor /= (double)uDiffCount;
}
else
{
vDifferences.Add(iDiff, 1);
}
}
uint uCharCount;
if (vCharCounts.TryGetValue(tch, out uCharCount))
{
++uCharCount;
vCharCounts[tch] = uCharCount;
dblEffectiveLength += dblDiffFactor * (1.0 / (double)uCharCount);
}
else
{
vCharCounts.Add(tch, 1);
dblEffectiveLength += dblDiffFactor;
}
}
uint uCharSpace = 0;
if (bChControl)
{
uCharSpace += (uint)CharSpaceBits.Control;
}
if (bChUpper)
{
uCharSpace += (uint)CharSpaceBits.Alpha;
}
if (bChLower)
{
uCharSpace += (uint)CharSpaceBits.Alpha;
}
if (bChNumber)
{
uCharSpace += (uint)CharSpaceBits.Number;
}
if (bChSpecial)
{
uCharSpace += (uint)CharSpaceBits.Special;
}
if (bChHigh)
{
uCharSpace += (uint)CharSpaceBits.High;
}
if (uCharSpace == 0)
{
return(0);
}
double dblBitsPerChar = Math.Log((double)uCharSpace) / Math.Log(2.0);
double dblRating = dblBitsPerChar * dblEffectiveLength;
#if !KeePassLibSD
char[] vLowerCopy = new char[vPasswordChars.Length];
for (int ilc = 0; ilc < vLowerCopy.Length; ++ilc)
{
vLowerCopy[ilc] = char.ToLower(vPasswordChars[ilc]);
}
if (PopularPasswords.IsPopularPassword(vLowerCopy))
{
dblRating /= 8.0;
}
Array.Clear(vLowerCopy, 0, vLowerCopy.Length);
#endif
return((uint)Math.Ceiling(dblRating));
}