paramgen.cpp

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using namespace std;

#include <string>
#include <iostream>
#include <fstream>
#include <curses.h>
#include <exception>
#include "Zerocoin.h"

#define DEFAULT_MODULUS_SIZE    3072
#define MIN_MODULUS_SIZE        1026

using namespace libzerocoin;

void
PrintWarning()
{
        cout << "Zerocoin parameter generation utility" << endl;
        cout << "-------------------------------------" << endl << endl;
        cout << "This utility generates an l-bit modulus N as the product of" << endl;
        cout << "two safe primes p, q. The values p and q are not stored." << endl;
        cout << "Call this program with no arguments to see usage options." << endl;
        cout << endl;
        cout << "SECURITY WARNING: ZEROCOIN PARAMETERS MUST BE GENERATED BY" << endl;
        cout << "A TRUSTED PARTY WHO DOES NOT STORE THE FACTORS. WHILE WE MAKE" << endl;
        cout << "A BEST EFFORT TO DESTROY THIS INFORMATION WE DO NOT TAKE" << endl;
        cout << "SPECIAL PRECAUTIONS TO ENSURE THAT THEY ARE DESTROYED." << endl;
        cout << endl;
        cout << "USE THIS UTILITY AT YOUR OWN RISK" << endl << endl;
}

void usage()
{
        printf("Usage:\n");
        printf(" -b <numbits>\n");
        printf(" -o <output file>\n");

        exit (8);
}

int main(int argc, char **argv)
{
        static Bignum resultModulus(0);
        uint32_t numBits = DEFAULT_MODULUS_SIZE;
        ofstream outfile;
        char* outfileName;
        bool writeToFile = false;

        while ((argc > 1) && (argv[1][0] == '-'))
        {
                switch (argv[1][1])
                {
                case 'b':
                        numBits = atoi(argv[2]);
                        ++argv;
                        --argc;
                        break;

                case 'o':
                        outfileName = argv[2];
                        writeToFile = true;
                        break;

                case 'h':
                        usage();
                        break;

                default:
                        printf("Wrong Argument: %s\n", argv[1]);
                        usage();
                        break;
                }

                ++argv;
                --argc;
        }

        if (numBits < MIN_MODULUS_SIZE) {
                cout << "Modulus is below minimum length (" << MIN_MODULUS_SIZE << ") bits" << endl;
                return(0);
        }

        PrintWarning();

        cout << "Modulus size set to " << numBits << " bits." << endl;
        cout << "Generating parameters. This may take a few minutes..." << endl;

        // Generate two safe primes "p" and "q"
        Bignum *p, *q;
        p = new Bignum(0);
        q = new Bignum(0);
        *p = Bignum::generatePrime(numBits / 2, true);
        *q = Bignum::generatePrime(numBits / 2, true);

        // Multiply to compute N
        resultModulus = (*p) * (*q);

        // Wipe out the factors
        delete p;
        delete q;

        // Convert to a hexidecimal string
        std::string resultHex = resultModulus.ToString(16);

        cout << endl << "N = " << endl << resultHex << endl;

        if (writeToFile) {
                try {
                        outfile.open (outfileName);
                        outfile << resultHex;
                        outfile.close();
                        cout << endl << "Result has been written to file '" << outfileName << "'." << endl;
                } catch (std::runtime_error &e) {
                        cout << "Unable to write to file:" << e.what() << endl;
                }
        }
}