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 = HammingDistribution(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);
}
