public void TwentyObservations()
{
BinomialSketch sketch = new BinomialSketch(1024*1024*1024, 64, "Louis Tully as played by Rick Moranis");
string somethingToObserve = "Gosh. It's a nice day out, isn't it?";
int observationCount = sketch.GetNumberOfIndexesSet(somethingToObserve);
for (int i = 0; i < 20; i++)
{
int lastCount = sketch.Observe(somethingToObserve);
Assert.Equal(observationCount, lastCount);
observationCount++;
}
Assert.Equal(observationCount, sketch.GetNumberOfIndexesSet(somethingToObserve));
double pNullHypothesis = sketch.TestNullHypothesisThatAllIndexesWereSetByChance(observationCount);
Assert.True(pNullHypothesis < 0.01);
int minObservationsAtOnePercentConfidence = sketch.CountObservationsForGivenConfidence(observationCount,
0.01d);
Assert.True(minObservationsAtOnePercentConfidence > 5);
}
public PasswordPopularityTracker(
string keyToPreventAlgorithmicComplexityAttacks,
long estimatedNumberOfAccounts = DefaultEstimatedNumberOfAccounts,
int thresholdRequiredToTrackPreciseOccurrences = DefaultMinCountRequiredToTrackPreciseOccurrences,
uint thresholdRequiredToStorePlaintext = DefaultMinCountRequiredToStorePlaintext,
double minPercentRequiredToStorePlaintext = DefaultMinPercentRequiredToStorePlaintext)
{
int numberOfHistoricalPeriods = DefaultNumberOfHistoricalPeriods;
uint factorOfGrowthBetweenHistoricalPeriods = DefaultFactorOfGrowthBetweenHistoricalPeriods;
LengthOfHistoricalPeriods = new uint[numberOfHistoricalPeriods];
PasswordFrequencyEstimatesForDifferentPeriods = new List<FrequencyTracker<string>>(DefaultNumberOfHistoricalPeriods);
uint currentPeriodLength = DefaultLengthOfShortestHistoricalPeriod;
for (int period = 0; period < DefaultNumberOfHistoricalPeriods; period++)
{
LengthOfHistoricalPeriods[period] = currentPeriodLength;
PasswordFrequencyEstimatesForDifferentPeriods.Add(
new FrequencyTracker<string>((int) currentPeriodLength));
currentPeriodLength *= factorOfGrowthBetweenHistoricalPeriods;
}
// Reverese the frequency trackers so that the one that tracks the most items is first on the list.
PasswordFrequencyEstimatesForDifferentPeriods.Reverse();
long conservativelyHighEstimateOfRowsNeeded = 4 * estimatedNumberOfAccounts / LowEndEstimateOfLoginsBetweenBenignUsersEnteringWrongPasswordRepeatedly;
_minCountRequiredToTrackPreciseOccurrences = thresholdRequiredToTrackPreciseOccurrences;
_minPercentRequiredToStorePlaintext = minPercentRequiredToStorePlaintext;
_minCountRequiredToStorePlaintext = thresholdRequiredToStorePlaintext;
// _minPercentRequiredToTrackPreciseOccurrences = minPercentRequiredToTrackPreciseOccurrences;
FailedPasswordsRecordedSoFar = 0d;
SketchForTestingIfNonexistentAccountIpPasswordHasBeenSeenBefore =
new AgingMembershipSketch(DefaultNumberOfSketchColumns, conservativelyHighEstimateOfRowsNeeded);
BinomialSketchOfFailedPasswords = new BinomialSketch(SizeOfBinomialLadder, HeightOfBinomialLadder, keyToPreventAlgorithmicComplexityAttacks); // FIXME configuration parameters
MapOfHighlyPopularUnsaltedHashedPasswordsToPlaintextPasswords =
new Dictionary<string, string>();
}
