dgk.h

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/*
 libdgk - v0.9
 A library implementing the DGK crypto system with full decryption

 Thanks to Marina Blanton for sharing her Miracl DGK implementation from
 M. Blanton and P. Gasti, "Secure and efficient protocols for iris and fingerprint identification" (ESORICS’11)
 with us. We used it as a template for this GMP version.

 The implementation structure was inspired by
 libpailler - A library implementing the Paillier crypto system. (http://hms.isi.jhu.edu/acsc/libpaillier/)

 Copyright (C) 2015 EC SPRIDE
 daniel.demmler@ec-spride.de

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful, but
 WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 General Public License for more details.
 */

#ifndef _DGK_H_
#define _DGK_H_
#include <gmp.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include "powmod.h"

/*
 This represents a DGK public key.
 */
typedef struct {
    unsigned int bits; /* key bits e.g., 1024 */
    unsigned int lbits; /* share (message) length e.g., 32 */
    mpz_t n; /* public modulus n = pq */
    mpz_t u; /* u = 2^lbits (uses 2^(2lbits+2) internally) */
    mpz_t g; /* generator g */
    mpz_t h; /* generator h */
} dgk_pubkey_t;

/*
 This represents a DGK private key; it needs to be used with a
 dgk_pubkey_t to be meaningful.
 */
typedef struct {
    mpz_t vp;
    mpz_t vq;
    mpz_t p;
    mpz_t q;
    mpz_t p_minusone;
    mpz_t q_minusone;
    mpz_t pinv;
    mpz_t qinv;
} dgk_prvkey_t;

extern mpz_t* powtwo;
extern mpz_t* gvpvqp;

void dgk_keygen(unsigned int modulusbits, unsigned int lbits, dgk_pubkey_t** pub, dgk_prvkey_t** prv);

//void dgk_encrypt_db(mpz_t res, dgk_pubkey_t* pub, mpz_t pt, gmp_randstate_t rnd);
void dgk_encrypt_fb(mpz_t res, dgk_pubkey_t* pub, mpz_t pt, gmp_randstate_t rnd);

void dgk_encrypt_plain(mpz_t res, dgk_pubkey_t* pub, mpz_t pt, gmp_randstate_t rnd);

void dgk_encrypt_crt(mpz_t res, dgk_pubkey_t* pub, dgk_prvkey_t* prv, mpz_t pt, gmp_randstate_t rnd);

// void dgk_encrypt_crt_db(mpz_t res, dgk_pubkey_t* pub, dgk_prvkey_t* prv, mpz_t pt, gmp_randstate_t rnd);
void dgk_decrypt(mpz_t res, dgk_pubkey_t* pub, dgk_prvkey_t* prv, mpz_t ct);

void dgk_storekey(unsigned int modulusbits, unsigned int lbits, dgk_pubkey_t* pub, dgk_prvkey_t* prv);

void dgk_readkey(unsigned int modulusbits, unsigned int lbits, dgk_pubkey_t** pub, dgk_prvkey_t** prv);

/*
 These free the structures allocated and returned by various
 functions within library and should be used when the structures are
 no longer needed.
 */
void dgk_freepubkey(dgk_pubkey_t* pub);
void dgk_freeprvkey(dgk_prvkey_t* prv);

void dgk_complete_pubkey(unsigned int modulusbits, unsigned int lbits, dgk_pubkey_t** pub, mpz_t n, mpz_t g, mpz_t h);

// void createKeys(){
//void test_encdec()

//void test_sharing(){
#endif