public void WriteCalibrationResult(Argon2CalibrationResult result)
{
WriteBeginCalibrationTest(result.Parameters);
WriteCompleteCalibrationTest(result.ElapsedMilliseconds);
}
public IEnumerable <Argon2CalibrationResult> Run()
{
//
// password and salt will be 128-bits, which is sufficient
// for all applications [Section 9].
//
var password = new string('0', _input.SaltAndPasswordLength);
var salt = new string('1', _input.SaltAndPasswordLength);
//
// the maximum time it should take to calculate the
// password hash.
//
var maximumTime = _input.MaximumTime;
//
// degree of parallelism should be twice the number of
// cpu cores [Section 6.4]
//
var degreeOfParallelism = _input.DegreeOfParallelism;
//
// we will start at 1MB and work our way up to an acceptable
// level. this memory usage is specified in KB.
//
var results = new List <Argon2CalibrationResult>();
for (int memoryUsage = 1024; memoryUsage <= 4 * 1024 * 1024; memoryUsage *= 2)
{
//
// figure out the maximum number of iterations such that the
// running time does not exceed the maximum time. if the
// running time exceeds the maximum time for a single iteration
// then reduce the memory usage accordingly and try again.
//
Argon2CalibrationResult bestResult = null;
var iterationSearch = new ExponentialSearch(_input.MinimumIterations, int.MaxValue, iterations =>
{
var parameters = new Argon2Parameters()
{
DegreeOfParallelism = degreeOfParallelism,
Iterations = iterations,
MemoryUsage = memoryUsage
};
//
// argon2id is preferred for password storage.
//
var argon2 = _argon2Factory.Create(_input.Mode, password, salt, parameters);
_logger.WriteBeginCalibrationTest(parameters);
var stopwatch = Stopwatch.StartNew();
argon2.GetBytes(_input.HashLength);
stopwatch.Stop();
var elapsedTime = stopwatch.ElapsedMilliseconds;
_logger.WriteCompleteCalibrationTest(elapsedTime);
//
// store off the best (slowest) number of iterations for this memory usage.
//
if (elapsedTime <= maximumTime && (bestResult == null || elapsedTime > bestResult.ElapsedMilliseconds))
{
bestResult = new Argon2CalibrationResult()
{
ElapsedMilliseconds = elapsedTime,
Parameters = parameters
};
}
if (elapsedTime > maximumTime)
{
return(ExponentialSearchComparison.ToHigh);
}
else if (elapsedTime < maximumTime)
{
return(ExponentialSearchComparison.ToLow);
}
else
{
return(ExponentialSearchComparison.Equal);
}
});
//
// if there was a best result for this memory usage and
// iteration combo, then store for later consumption.
//
iterationSearch.Search();
if (bestResult != null)
{
results.Add(bestResult);
}
}
//
// highest usage of memory and thread count should be recommended
// first. we'll reverse the results so the consumer receives
// them in recommended order.
//
results.Reverse();
return(results);
}