是否有办法在c++中实现c# Random()类?我特别需要根据给定的种子生成相同的数字序列。
的场景:我正在努力通过利用c#中Random()的使用来"破解"几个加密恶意软件来生成密钥。显然,这是弱的,只有2^32个可能的密钥,约4.3B个密钥,这是在猜测的可能性范围内。我曾经用c#写过brute - forcers,但是无论我如何优化,它们都相当慢。我想在c++中实现一个brute - forcer以获得最佳效率("更接近硬件"),因为我可以通过解密部分获得更好的速度优化(例如AES-256通常,将来甚至可以利用GPU),并以指数方式获得更好的输出。
显然,Random(seed) != srand(seed),基于不同的生成器。有没有一种方法可以在c++中实现c#使用的PRNG ?我显然不能修改c#恶意软件,因为加密已经对受害者的文件进行了加密,所以我不能只是"重写两者以使用相同的通用RNG"。
你可以在这里看到Random (c#)的源代码
感谢大家的回答和评论。我在这里发布了我移植的c++代码,如果有人需要它用于类似的项目。这是复制/粘贴,只需要"翻译"几行,并将其分解成合适的原型。确认并排产生与c#应用程序完全相同的数字序列。:)
Random.h
#include <limits>
#pragma once
class Random
{
private:
const int MBIG = INT_MAX;
const int MSEED = 161803398;
const int MZ = 0;
int inext;
int inextp;
int *SeedArray = new int[56]();
double Sample();
double GetSampleForLargeRange();
int InternalSample();
public:
Random(int seed);
~Random();
int Next();
int Next(int minValue, int maxValue);
int Next(int maxValue);
double NextDouble();
};
Random.cpp
#include "stdafx.h"
#include "Random.h"
#include <limits.h>
#include <math.h>
#include <stdexcept>
double Random::Sample() {
//Including this division at the end gives us significantly improved
//random number distribution.
return (this->InternalSample()*(1.0 / MBIG));
}
int Random::InternalSample() {
int retVal;
int locINext = this->inext;
int locINextp = this->inextp;
if (++locINext >= 56) locINext = 1;
if (++locINextp >= 56) locINextp = 1;
retVal = SeedArray[locINext] - SeedArray[locINextp];
if (retVal == MBIG) retVal--;
if (retVal<0) retVal += MBIG;
SeedArray[locINext] = retVal;
inext = locINext;
inextp = locINextp;
return retVal;
}
Random::Random(int seed) {
int ii;
int mj, mk;
//Initialize our Seed array.
//This algorithm comes from Numerical Recipes in C (2nd Ed.)
int subtraction = (seed == INT_MAX) ? INT_MAX : abs(seed);
mj = MSEED - subtraction;
SeedArray[55] = mj;
mk = 1;
for (int i = 1; i<55; i++) { //Apparently the range [1..55] is special (Knuth) and so we're wasting the 0'th position.
ii = (21 * i) % 55;
SeedArray[ii] = mk;
mk = mj - mk;
if (mk<0) mk += MBIG;
mj = SeedArray[ii];
}
for (int k = 1; k<5; k++) {
for (int i = 1; i<56; i++) {
SeedArray[i] -= SeedArray[1 + (i + 30) % 55];
if (SeedArray[i]<0) SeedArray[i] += MBIG;
}
}
inext = 0;
inextp = 21;
seed = 1;
}
Random::~Random()
{
delete SeedArray;
}
int Random::Next() {
return this->InternalSample();
}
double Random::GetSampleForLargeRange() {
int result = this->InternalSample();
// Note we can't use addition here. The distribution will be bad if we do that.
bool negative = (InternalSample() % 2 == 0) ? true : false; // decide the sign based on second sample
if (negative) {
result = -result;
}
double d = result;
d += (INT_MAX - 1); // get a number in range [0 .. 2 * Int32MaxValue - 1)
d /= 2 * INT_MAX - 1;
return d;
}
int Random::Next(int minValue, int maxValue) {
if (minValue>maxValue) {
throw std::invalid_argument("minValue is larger than maxValue");
}
long range = (long)maxValue - minValue;
if (range <= (long)INT_MAX) {
return ((int)(this->Sample() * range) + minValue);
}
else {
return (int)((long)(this->GetSampleForLargeRange() * range) + minValue);
}
}
int Random::Next(int maxValue) {
if (maxValue<0) {
throw std::invalid_argument("maxValue must be positive");
}
return (int)(this->Sample()*maxValue);
}
double Random::NextDouble() {
return this->Sample();
}
Main.cpp
#include "Random.h"
#include <iostream>
int main(int argc, char* argv[]){
// Example usage with a given seed
Random r = Random(7898);
std::cout << r.Next() << std::endl;
}