如何在Crypto ++中使用Shamir Secret Sharing类 [英] How to use Shamir Secret Sharing Class in Crypto++

问题描述

我试图在Crypto ++中使用 SecretSharing 类，但是我无法使用

I tried to use the SecretSharing Class in Crypto++, but I couldn't make it work.

这是我的代码：

using namespace CryptoPP;

void secretSharing(){
    AutoSeededRandomPool rng;
    SecretSharing shamir(rng, 4, 6); 
    byte test[] = {'a', 'b', 'c', 'd'};
    shamir.Put(test, 4); 
    //shamir.MessageEnd();

    //cout << shamir.TotalBytesRetrievable() <<endl;
}

编译并运行后，我将得到：

After compile and run, I will get:

./main 
terminate called after throwing an instance of 'CryptoPP::BufferedTransformation::NoChannelSupport'
  what():  unknown: this object doesn't support multiple channels
[1]    3597 abort (core dumped)  ./main

SecretSharing :: SecretSharing（）的声明是：

SecretSharing（ RandomNumberGenerator& rng，int阈值，int nShares，BufferedTransformation * attachment = NULL，bool addPadding = true）

我应该给它一个 BufferedTransformation * ，但是究竟应该使用哪个类？

Should I give it a BufferedTransformation*, but exactly which class should I use?

Crypto ++中是否有任何秘密共享示例代码？

Are there any Secret Sharing example code in Crypto++?

推荐答案

void SecretShareFile(int threshold, int nShares, const char *filename, const char *seed)
{
    RandomPool rng;
    rng.IncorporateEntropy((byte *)seed, strlen(seed));

    ChannelSwitch *channelSwitch;
    FileSource source(filename, false, new SecretSharing(rng,
        threshold, nShares, channelSwitch = new ChannelSwitch));

    vector_member_ptrs<FileSink> fileSinks(nShares);
    string channel;
    for (int i=0; i<nShares; i++)
    {
        char extension[5] = ".000";
        extension[1]='0'+byte(i/100);
        extension[2]='0'+byte((i/10)%10);
        extension[3]='0'+byte(i%10);
        fileSinks[i].reset(new FileSink((string(filename)+extension).c_str()));

        channel = WordToString<word32>(i);
        fileSinks[i]->Put((byte *)channel.data(), 4);
        channelSwitch->AddRoute(channel, *fileSinks[i], DEFAULT_CHANNEL);
    }

    source.PumpAll();
}

在上面的代码中，有一个名为 ChannelSwitch 用 new 创建的变量。 文件源 源拥有它，并将其删除。但是他需要一个命名变量（而不是匿名变量或临时变量），因为后来他调用 channelSwitch-> AddRoute

In the code above, there's a named ChannelSwitch variable created with new. The FileSource source owns it and will delete it. But he needed a named variable (and not an anonymous or temporary) because he later calls channelSwitch->AddRoute

Wei可以使用 Redirector 来做到这一点，以允许进行堆栈分配（不使用内存管理器），并确保 FileSource 过滤器不会将其删除：

Wei could have done it with a Redirector to allow a stack allocation (stay out of the memory manager) and to ensure the FileSource filter does not delete it:

ChannelSwitch channelSwitch;
FileSource source(filename, false, new SecretSharing(rng,
    threshold, nShares, new Redirector(channelSwitch));
...
channelSwitch.AddRoute(channel, *fileSinks[i], DEFAULT_CHANNEL);

以及恢复代码：

void SecretRecoverFile(int threshold, const char *outFilename, char *const *inFilenames)
{
    SecretRecovery recovery(threshold, new FileSink(outFilename));

    vector_member_ptrs<FileSource> fileSources(threshold);
    SecByteBlock channel(4);
    int i;
    for (i=0; i<threshold; i++)
    {
        fileSources[i].reset(new FileSource(inFilenames[i], false));
        fileSources[i]->Pump(4);
        fileSources[i]->Get(channel, 4);
        fileSources[i]->Attach(new ChannelSwitch(recovery, string((char *)channel.begin(), 4)));
    }

    while (fileSources[0]->Pump(256))
        for (i=1; i<threshold; i++)
            fileSources[i]->Pump(256);

    for (i=0; i<threshold; i++)
        fileSources[i]->PumpAll();
}

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