www.pudn.com > miracl.zip > CRSETUP.CPP

/* 
 *   Cramer-Shoup Public Key Cryptography 
 * 
 *   This program generates the common values q, p, g1 and g2 to a file 
 *   common.crs 
 * 
 *   Requires: big.cpp 
 * 
 *   Copyright (c) 1999 Shamus Software Ltd. 
 */ 
 
#include  
#include  
#include  
 
using namespace std; 
 
#define PBITS 1024  
#define QBITS 160 
 
Miracl precision=100; 
 
int main() 
{ 
    ofstream common("common.crs");    // construct file I/O streams 
    Big p,q,h,t,s,r,n,g; 
    long seed; 
    cout << "Enter 9 digit random number seed  = "; 
    cin >> seed; 
    irand(seed); 
 
    get_mip()->IOBASE=16; 
 
/* generate q */ 
    forever 
    { 
        n=rand(QBITS-2,2);  /* QBIT-2 bit number, base 2 */ 
        q=2*n+1; 
        while (!prime(q)) q+=2; 
        if (bits(q)>=QBITS) continue; 
        break; 
    } 
    cout << "q= " << q << endl; 
    common << PBITS << endl; 
    common << q << endl; 
 
/* generate p */ 
    t=(pow((Big)2,PBITS)-1)/(2*q); 
    s=(pow((Big)2,PBITS-1)-1)/(2*q); 
    forever  
    { 
        n=rand(t); 
        if (n