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/*
vote sample tool
Copyright (c) 2014, National Institute of Advanced Industrial
Science and Technology All rights reserved.
This source file is subject to BSD 3-Clause license.
modifyed for mcl by herumi
*/
#include <iostream>
#include <fstream>
#include <cybozu/random_generator.hpp>
#include <cybozu/option.hpp>
#include <cybozu/itoa.hpp>
#include <mcl/fp.hpp>
#include <mcl/ec.hpp>
#include <mcl/elgamal.hpp>
#include <mcl/ecparam.hpp>
typedef mcl::FpT<> Fp;
typedef mcl::FpT<mcl::ZnTag> Zn; // use ZnTag because Zn is different class with Fp
typedef mcl::EcT<Fp> Ec;
typedef mcl::ElgamalT<Ec, Zn> Elgamal;
cybozu::RandomGenerator rg;
const std::string pubFile = "vote_pub.txt";
const std::string prvFile = "vote_prv.txt";
const std::string resultFile = "vote_ret.txt";
std::string GetSheetName(size_t n)
{
return std::string("vote_") + cybozu::itoa(n) + ".txt";
}
struct Param {
std::string mode;
std::string voteList;
Param(int argc, const char *const argv[])
{
cybozu::Option opt;
opt.appendOpt(&voteList, "11001100", "l", ": list of voters for vote mode(eg. 11001100)");
opt.appendHelp("h", ": put this message");
opt.appendParam(&mode, "mode", ": init/vote/count/open");
if (!opt.parse(argc, argv)) {
opt.usage();
exit(1);
}
printf("mode=%s\n", mode.c_str());
if (mode == "vote") {
printf("voters=%s\n", voteList.c_str());
size_t pos = voteList.find_first_not_of("01");
if (pos != std::string::npos) {
printf("bad char %c\n", voteList[pos]);
exit(1);
}
}
}
};
void SysInit()
{
const mcl::EcParam& para = mcl::ecparam::secp192k1;
Zn::init(para.n);
Fp::init(para.p);
Ec::init(para.a, para.b);
}
template<class T>
bool Load(T& t, const std::string& name, bool doThrow = true)
{
std::ifstream ifs(name.c_str(), std::ios::binary);
if (!ifs) {
if (doThrow) throw cybozu::Exception("Load:can't read") << name;
return false;
}
if (ifs >> t) return true;
if (doThrow) throw cybozu::Exception("Load:bad data") << name;
return false;
}
template<class T>
void Save(const std::string& name, const T& t)
{
std::ofstream ofs(name.c_str(), std::ios::binary);
ofs << t;
}
void Init()
{
const mcl::EcParam& para = mcl::ecparam::secp192k1;
const Fp x0(para.gx);
const Fp y0(para.gy);
const Ec P(x0, y0);
const size_t bitSize = para.bitSize;
Elgamal::PrivateKey prv;
prv.init(P, bitSize, rg);
const Elgamal::PublicKey& pub = prv.getPublicKey();
printf("make privateKey=%s, publicKey=%s\n", prvFile.c_str(), pubFile.c_str());
Save(prvFile, prv);
Save(pubFile, pub);
}
struct CipherWithZkp {
Elgamal::CipherText c;
Elgamal::Zkp zkp;
bool verify(const Elgamal::PublicKey& pub) const
{
return pub.verify(c, zkp);
}
};
inline std::ostream& operator<<(std::ostream& os, const CipherWithZkp& self)
{
return os << self.c << std::endl << self.zkp;
}
inline std::istream& operator>>(std::istream& is, CipherWithZkp& self)
{
return is >> self.c >> self.zkp;
}
void Vote(const std::string& voteList)
{
Elgamal::PublicKey pub;
Load(pub, pubFile);
puts("shuffle");
std::vector<size_t> idxTbl(voteList.size());
for (size_t i = 0; i < idxTbl.size(); i++) {
idxTbl[i] = i;
}
cybozu::shuffle(idxTbl, rg);
puts("each voter votes");
for (size_t i = 0; i < voteList.size(); i++) {
CipherWithZkp c;
pub.encWithZkp(c.c, c.zkp, voteList[i] - '0', rg);
const std::string sheetName = GetSheetName(idxTbl[i]);
printf("make %s\n", sheetName.c_str());
Save(sheetName, c);
}
}
void Count()
{
Elgamal::PublicKey pub;
Load(pub, pubFile);
Elgamal::CipherText result;
puts("aggregate votes");
for (size_t i = 0; ; i++) {
const std::string sheetName = GetSheetName(i);
CipherWithZkp c;
if (!Load(c, sheetName, false)) break;
if (!c.verify(pub)) throw cybozu::Exception("bad cipher text") << i;
printf("add %s\n", sheetName.c_str());
result.add(c.c);
}
printf("create result file : %s\n", resultFile.c_str());
Save(resultFile, result);
}
void Open()
{
Elgamal::PrivateKey prv;
Load(prv, prvFile);
Elgamal::CipherText c;
Load(c, resultFile);
Zn n;
prv.dec(n, c);
std::cout << "result of vote count " << n << std::endl;
#if 0
puts("open real value");
for (size_t i = 0; ; i++) {
Elgamal::CipherText c;
const std::string sheetName = GetSheetName(i);
if (!Load(c, sheetName, false)) break;
Zn n;
prv.dec(n, c);
std::cout << sheetName << " " << n << std::endl;
}
#endif
}
int main(int argc, char *argv[])
try
{
const Param p(argc, argv);
SysInit();
if (p.mode == "init") {
Init();
} else
if (p.mode == "vote") {
Vote(p.voteList);
} else
if (p.mode == "count") {
Count();
} else
if (p.mode == "open") {
Open();
} else
{
printf("bad mode=%s\n", p.mode.c_str());
return 1;
}
} catch (std::exception& e) {
printf("ERR %s\n", e.what());
}
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