/// <summary>
/// Task 3. Collision
/// </summary>
private static void FindAndPrintCollision()
{
// asking user how many bits (counting from the beginning of initial message) he wants to be the same
var k = ConsoleMessager.AskHashLength();
// asking length for future string value generating
var L = ConsoleMessager.AskStringLength();
// a dictionary where key is a bits piece and value is a random generated string
var kBitsStringHashDict = new Dictionary <string, string>();
while (true)
{
var randString = GetRandomString(L);
var mdFourInstance = GetHashFromString(randString);
var firstBitsList = GetBitsList(mdFourInstance.ResultHashBytes, k);
var firstBitsString = Helper.PrintList(firstBitsList);
// when we try to add the same key an exception is going to be raised.
// that means a collision has been found.
try
{
kBitsStringHashDict.Add(firstBitsString, randString);
}
catch (ArgumentException e)
{
var firstHash = GetHashFromString(kBitsStringHashDict[firstBitsString]).ResultHashString;
var secondHash = mdFourInstance.ResultHashString;
var firstRandomString = kBitsStringHashDict[firstBitsString];
var secondRandomString = randString;
var N = kBitsStringHashDict.Count;
ConsoleMessager.PrintCollisionResults(firstHash, firstRandomString, secondHash, secondRandomString,
firstBitsString, N);
break;
}
}
}
/// <summary>
/// Task 4. Prototype
/// </summary>
private static void FindAndPrintPrototype()
{
Console.WriteLine("Enter a password:"******"";
int N = 0;
while (prototypeString == "")
{
N++;
var randomString = GetRandomString(L);
var mdFourRandomStringInstance = GetHashFromString(randomString);
var randomHashFirstBitsList = GetBitsList(mdFourRandomStringInstance.ResultHashBytes, k);
var randomHashFirstBitsString = Helper.PrintList(randomHashFirstBitsList);
if (randomHashFirstBitsString == firstBitsString)
{
Console.WriteLine(String.Format("We found a string with the same {0} first bits in hash for your password '{1}'", k, inputPassword));
prototypeString = randomString;
ConsoleMessager.PrintCollisionResults(mdFourInitialInstance.ResultHashString, inputPassword,
mdFourRandomStringInstance.ResultHashString, randomString, randomHashFirstBitsString, N);
}
}
}
