[英]Emulate C# Random() in C++ (Same Numbers)
Is there a way to implement the C# Random() class in C++? 有没有办法在C ++中实现C#Random()类? I specifically need to generate the same number sequences based on a given seed. 我特别需要根据给定的种子生成相同的数字序列。
The scenario: I am working to "break" several encrypting malware by exploiting their usage of Random() in C# to generate the key. 场景:我正在努力通过利用他们在C#中使用Random()来“破解”几个加密恶意软件来生成密钥。 Obviously this is weak to having only 2^32 possible keys, ~4.3B keys, which is in the realm of possibility to guess. 显然,只有2 ^ 32个可能的密钥,~4.3B密钥,这是可能的猜测范围。 I have written bruteforcers in C#, but they are rather slow, no matter how much I optimize. 我在C#中编写了强力执行器,但无论我优化多少,它们都相当慢。 I would like to implement a bruteforcer in C++ for the best efficiency ("closer to the hardware"), as I can get much better speed optimizations with the decryption part (eg AES-256 typically, could even leverage a GPU in the future), and exponentially get better outputs. 我想用C ++实现一个bruteforcer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通常甚至可以在未来利用GPU) ,并以指数方式获得更好的产出。
Obviously, Random(seed) != srand(seed), based on being different generators. 显然,随机(种子)!= srand(种子),基于不同的生成器。 Is there a way to implement the PRNG C# uses, in C++? 有没有办法在C ++中实现PRNG C#用途? I obviously cannot modify the C# malware, as the encryption has already been done to the victim's files, so I cannot just "rewrite both to use the same common RNG". 我显然无法修改C#恶意软件,因为已经对受害者的文件进行了加密,因此我不能只是“重写两者以使用相同的常见RNG”。
您可以在此处查看Random(在c#中)的源代码。
Thanks everyone for the answers and comments. 感谢大家的回答和评论。 I am posting my ported C++ code here if anyone else needs it for a similar project. 我在这里发布我的移植C ++代码,如果其他人需要它来进行类似的项目。 It was pretty copy/paste, and only had to "translate" a few lines, and break it out into a proper prototype. 这是相当复制/粘贴,只需要“翻译”几行,并将其分解为适当的原型。 Confirmed to side-by-side produce the exact same number sequences as a C# application. 确认并排生成与C#应用程序完全相同的数字序列。 :) :)
Random.h 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 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 Main.cpp的
#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;
}
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