ibe_ext.cpp

椭圆曲线加密算法

/*
   Boneh & Franklin's Identity Based Encryption

   Extract Phase

   After this program has run the file private.ibe contains

   <Private point Did - y coordinate>

 */
/*
#include <iostream>
#include <fstream>
#include <cstring>
#include "ecn.h"
#include "zzn.h"
*/
#include "ibe.h"
using namespace std;

// Using SHA-256 as basic hash algorithm

///#define HASH_LEN 32

//
// Hash function
// 
/*
Big H1(char *string)
{ // Hash a zero-terminated string to a number < modulus
    Big h,p;
    char s[HASH_LEN];
    int i,j; 
    sha256 sh;

    shs256_init(&sh);

    for (i=0;;i++)
    {
        if (string[i]==0) break;
        shs256_process(&sh,string[i]);
    }
    shs256_hash(&sh,s);

    p=get_modulus();
    h=1; j=0; i=1;
    forever
    {
        h*=256; 
        if (j==HASH_LEN)  {h+=i++; j=0;}
        else         h+=s[j++];
        if (h>=p) break;
    }
    h%=p;
    return h;
}
****/
//
// Given y, get x=(y^2-1)^(1/3) mod p (from curve equation)
//
/*
Big getx(Big y)
{
    Big p=get_modulus();
    Big t=modmult(y+1,y-1,p);   // avoids overflow
    return pow(t,(2*p-1)/3,p);
}****/
 
//
// MapToPoint
//
/*
ECn map_to_point(char *ID)
{
    ECn Q;
    Big x0,y0=H1(ID);
 
    x0=getx(y0);

    Q.set(x0,y0);

    return Q;
}
****/
BOOL ibe_ext(char* id)
{
    miracl *mip=mirsys(18,0);     // thread-safe ready.  (36,0) for 1024 bit p
    ifstream common("common.ibe");
    ifstream master("master.ibe");
    ofstream private_key("private.ibe");
    ECn Qid,Did;
    Big p,q,cof,s,x,y;
    int bits;

    common >> bits;//////////////////////////////////////////////////////////////////////////////////////？？？
    mip->IOBASE=16;
    common >> p >> q;
    master >> s;
    mip->IOBASE=10;

    ecurve(0,1,p,MR_PROJECTIVE);//生成椭圆曲线y^2=x^3+1 mod p
    cof=(p+1)/q;/////////////////////////////////////////////////////////////////////////////////////////？？？

// EXTRACT

    //char id[1000];

    //cout << "Enter your email address (lower case)" << endl;
    //cin.getline(id,1000);

    Qid=map_to_point(id);//将id映射到一个q阶的点
    Did=s*Qid;//设置私钥Did,s为主密钥

    //cout << "Private key= " << Did << endl;

    Did.get(x,y);
    mip->IOBASE=16;
    private_key << y << endl;/////////////////////////////////////////////////////////////////////only y ??

    return 0;
}
/*
int main()
{
	char id[1000];
	cout << "Enter your email address (lower case)" << endl;
    cin.getline(id,1000);
	ibe_ext(id);
}*/