public static BigInteger2 getProbablePrime(int n) { BigInteger2 num = new BigInteger2(n); BigInteger2 zero = BigInteger2.Zero(); BigInteger2 temp = new BigInteger2(1, 0); BigInteger2 nem = ((BigInteger2)num.Clone()) + BigInteger2.T50(); bool success = true; int ni = 0; while (true) { ni++; Console.Out.WriteLine(ni); if (num < nem || num == nem) { foreach (int i in mySet) { bool[] val = BigInteger2.ConvertToBinary(i, 11); bool[] t = new bool[val.Length]; for (int x = 0; x < val.Length; x++) { t[x] = (val[x] ? true : false); } temp.bitlength = t; if (BigIntegerExtensions.DivideBy(num, temp)[1] == zero) { success = false; break; } } } if (success && BigIntegerExtensions.MillerRabinIsPrime(num)) { break; } if (num == nem) { success = true; var skip = DateTime.Now.Millisecond % 5; switch (skip) { case 0: num = num + BigInteger2.TWO(); nem = nem + BigInteger2.T50(); break; case 1: num = num + BigInteger2.FOUR(); nem = nem + BigInteger2.T100(); break; case 2: num = num + BigInteger2.T16(); nem = nem + BigInteger2.T100(); break; case 3: num = num + BigInteger2.T32(); nem = nem + BigInteger2.T100(); break; case 4: num = num + BigInteger2.T50(); nem = nem + BigInteger2.T100(); break; } } else { success = true; num = num + BigInteger2.TWO(); } } return(num); }
//MillerRabinTest public static bool MillerRabinIsPrime(BigInteger2 numb) { //Use Rabin's Test suite a.modPower(d,numb)== 1 : then numb is prime else numb composite BigInteger2 n = (BigInteger2)numb.Clone(); BigInteger2 numbLess1 = n - BigInteger2.ONE(); BigInteger2[] testSuite = new BigInteger2[3]; //Fill testSuite with BigInteger2 values: //Including 5, 11, and 61 testSuite[0] = new BigInteger2(1, 0); testSuite[0].bitlength = BigInteger2.ConvertToBinary(61, 6); testSuite[1] = new BigInteger2(1, 0); testSuite[1].bitlength = BigInteger2.ConvertToBinary(31, 6); testSuite[2] = new BigInteger2(1, 0); testSuite[2].bitlength = BigInteger2.ConvertToBinary(11, 4); // Determine two.power(r) factor of q: // By: using q is least set bit referenced from zero int i = 0, j = 0; for (i = numbLess1.bitlength.Length - 1, j = 0; i >= 2; i--, j++) { if (numbLess1.bitlength[i]) { break; } } //Console.Out.WriteLine("j: {0}", j.ToString()); //Form component two.power(r) = twoPowerR BigInteger2 twoPowerS = BigInteger2.TWO().power(j); //Calculate d: BigInteger2 d = BigIntegerExtensions.DivideBy(numbLess1, twoPowerS)[0]; //Use testSuite to eliminate Composites: bool isPrime = true; foreach (BigInteger2 integer in testSuite) { bool prime = false; BigInteger2 result = BigIntegerExtensions.modPower(integer, d, numb); if (result == BigInteger2.ONE()) { prime = true; continue; } else { for (i = 0; i < j; i++) { if ((numb - result) == BigInteger2.ONE()) { prime = true; break; } result = BigIntegerExtensions.modPower(result, BigInteger2.TWO(), numb); } if (prime) { continue; } else { isPrime = false; break; } } } return(isPrime); }