/// <summary>
/// Given the path of a file containing a count, followed by a space, followed by a password,
/// this method reads in the distribution and creates a password selector that can provide
/// passwords sampled from that distribution.
/// </summary>
/// <param name="pathToWeightedFrequencyFile"></param>
private void LoadPasswordSelector(string pathToWeightedFrequencyFile)
{
_passwordSelector = new WeightedSelector <string>();
// Created a weighted-random selector for paasswords based on the RockYou database.
using (System.IO.StreamReader file =
new System.IO.StreamReader(new FileStream(pathToWeightedFrequencyFile, FileMode.Open, FileAccess.Read)))
{
string lineWithCountFollowedBySpaceFollowedByPassword;
while ((lineWithCountFollowedBySpaceFollowedByPassword = file.ReadLine()) != null)
{
lineWithCountFollowedBySpaceFollowedByPassword =
lineWithCountFollowedBySpaceFollowedByPassword.Trim();
int indexOfFirstSpace = lineWithCountFollowedBySpaceFollowedByPassword.IndexOf(' ');
if (indexOfFirstSpace < 0 ||
indexOfFirstSpace + 1 >= lineWithCountFollowedBySpaceFollowedByPassword.Length)
{
continue; // The line is invalid as it doesn't have a space with a password after it
}
string countAsString = lineWithCountFollowedBySpaceFollowedByPassword.Substring(0, indexOfFirstSpace);
ulong count;
if (!ulong.TryParse(countAsString, out count))
{
continue; // The count field is invalid as it doesn't parse to an unsigned number
}
string password = lineWithCountFollowedBySpaceFollowedByPassword.Substring(indexOfFirstSpace + 1);
_passwordSelector.AddItem(password, count);
}
}
}
/// <summary>
/// Create a new selector that only contains the first <paramref name="count"/> items of this selector.
/// </summary>
/// <param name="count">The number of values to keep</param>
/// <returns>The new selector that has only the first <paramref name="count"/> items.</returns>
public WeightedSelector <T> TrimToInitialItems(int count)
{
WeightedSelector <T> trimmed = new WeightedSelector <T>();
count = Math.Min(count, _items.Count);
trimmed._items.AddRange(_items.Take(count));
trimmed._cumulativeWeight.AddRange(_cumulativeWeight.Take(count));
return(trimmed);
}
public WeightedSelector <T> TrimToRemoveInitialItems(int count)
{
WeightedSelector <T> trimmed = new WeightedSelector <T>();
count = Math.Min(count, _items.Count);
double weightRemoved = _cumulativeWeight[count];
trimmed._items.AddRange(_items.Skip(count));
trimmed._cumulativeWeight.AddRange(_cumulativeWeight.Skip(count).Select(x => x - weightRemoved));
return(trimmed);
}
public SimulatedPasswords(DebugLogger logger, ExperimentalConfiguration config)
{
_logger = logger;
_logger.WriteStatus("Loading popular password file");
LoadPasswordSelector(config.PasswordFrequencyFile);
if (config.PopularPasswordsToRemoveFromDistribution > 0)
{
_passwordSelector = _passwordSelector.TrimToRemoveInitialItems(config.PopularPasswordsToRemoveFromDistribution);
}
_logger.WriteStatus("Loading passwords known to be common by the algorithm before the attack");
LoadKnownPopularPasswords(config.PreviouslyKnownPopularPasswordFile);
_logger.WriteStatus("Creating common password selector");
_commonPasswordSelector = _passwordSelector.TrimToInitialItems(
(int)config.NumberOfPopularPasswordsForAttackerToExploit);
_logger.WriteStatus("Finished creating common password selector");
_logger.WriteStatus("Creating list of most common passwords");
OrderedListOfMostCommonPasswords =
_passwordSelector.GetItems();
_logger.WriteStatus("Finished creating list of most common passwords");
}