public void Challenge23_Clone_an_MT19937_RNG_from_its_output()
{
var rng = new MT19937();
rng.SeedMt(5489);
// run random number of ExtractNumber
// the cloning doesn't depend on internal index state
using (var crnd = RandomNumberGenerator.Create())
{
var runCount = CryptoRandom.GetInt(crnd, 1, 2000);
for (int i = 0; i < runCount; ++i)
{
rng.ExtractNumber();
}
}
var states = new List <uint>(624);
for (int i = 0; i < states.Capacity; ++i)
{
states.Add(rng.ExtractNumber());
}
var clone = MT19937Cloner.Clone(states);
for (int i = 0; i < 1000; ++i)
{
Assert.Equal(rng.ExtractNumber(), clone.ExtractNumber());
}
}
public void Challenge22_Crack_an_MT19937_seed()
{
int unixTimestamp;
uint seed;
uint currentRandomNumber;
using (var crnd = RandomNumberGenerator.Create())
{
unixTimestamp = (int)(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;
unixTimestamp += CryptoRandom.GetInt(crnd, 40, 1000);
var rng = new MT19937();
seed = (uint)unixTimestamp;
rng.SeedMt(seed);
unixTimestamp += CryptoRandom.GetInt(crnd, 40, 1000);
currentRandomNumber = rng.ExtractNumber();
}
// check every possible second from the last twenty-four hours
uint foundSeed = 0;
for (int i = unixTimestamp; i > (unixTimestamp - 86400); --i)
{
var rng = new MT19937();
rng.SeedMt((uint)i);
if (rng.ExtractNumber() == currentRandomNumber)
{
foundSeed = (uint)i;
break;
}
}
Assert.Equal(seed, foundSeed);
}