/*
 * libopenemv - a library to work with EMV family of smart cards
 * Copyright (C) 2015 Dmitry Eremin-Solenikov
 * Copyright (C) 2017 Merlok
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "crypto.h"
#include "crypto_backend.h"

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>

#include "rsa.h"
#include "sha1.h"

struct crypto_hash_polarssl {
	struct crypto_hash ch;
	sha1_context ctx;
};

static void crypto_hash_polarssl_close(struct crypto_hash *_ch)
{
	struct crypto_hash_polarssl *ch = (struct crypto_hash_polarssl *)_ch;

	free(ch);
}

static void crypto_hash_polarssl_write(struct crypto_hash *_ch, const unsigned char *buf, size_t len)
{
	struct crypto_hash_polarssl *ch = (struct crypto_hash_polarssl *)_ch;

	sha1_update(&(ch->ctx), buf, len);
}

static unsigned char *crypto_hash_polarssl_read(struct crypto_hash *_ch)
{
	struct crypto_hash_polarssl *ch = (struct crypto_hash_polarssl *)_ch;

	static unsigned char sha1sum[20];
	sha1_finish(&(ch->ctx), sha1sum);
	return sha1sum;
}

static size_t crypto_hash_polarssl_get_size(const struct crypto_hash *ch)
{
	if (ch->algo == HASH_SHA_1)
		return 20;
	else
		return 0;
}

static struct crypto_hash *crypto_hash_polarssl_open(enum crypto_algo_hash hash)
{
	if (hash != HASH_SHA_1)
		return NULL;

	struct crypto_hash_polarssl *ch = malloc(sizeof(*ch));

	sha1_starts(&(ch->ctx));

	ch->ch.write = crypto_hash_polarssl_write;
	ch->ch.read = crypto_hash_polarssl_read;
	ch->ch.close = crypto_hash_polarssl_close;
	ch->ch.get_size = crypto_hash_polarssl_get_size;

	return &ch->ch;
}

struct crypto_pk_polarssl {
	struct crypto_pk cp;
	rsa_context ctx;
};

static struct crypto_pk *crypto_pk_polarssl_open_rsa(va_list vl)
{
	struct crypto_pk_polarssl *cp = malloc(sizeof(*cp));
	memset(cp, 0x00, sizeof(*cp));

	char *mod = va_arg(vl, char *);	 // N
	int modlen = va_arg(vl, size_t);
	char *exp = va_arg(vl, char *);	 // E
	int explen = va_arg(vl, size_t);

	rsa_init(&cp->ctx, RSA_PKCS_V15, 0);
	
	cp->ctx.len = modlen; // size(N) in bytes
	mpi_read_binary(&cp->ctx.N, (const unsigned char *)mod, modlen);
	mpi_read_binary(&cp->ctx.E, (const unsigned char *)exp, explen);
	
	int res = rsa_check_pubkey(&cp->ctx);
	if(res != 0) {
		fprintf(stderr, "PolarSSL public key error res=%x exp=%d mod=%d.\n", res * -1, explen, modlen);

		return NULL;
	}

	return &cp->cp;
}

static struct crypto_pk *crypto_pk_polarssl_open_priv_rsa(va_list vl)
{
	struct crypto_pk_polarssl *cp = malloc(sizeof(*cp));
	memset(cp, 0x00, sizeof(*cp));
	char *mod = va_arg(vl, char *);
	int modlen = va_arg(vl, size_t);
	char *exp = va_arg(vl, char *);
	int explen = va_arg(vl, size_t);
	char *d = va_arg(vl, char *);
	int dlen = va_arg(vl, size_t);
	char *p = va_arg(vl, char *);
	int plen = va_arg(vl, size_t);
	char *q = va_arg(vl, char *);
	int qlen = va_arg(vl, size_t);
	char *dp = va_arg(vl, char *);
	int dplen = va_arg(vl, size_t);
	char *dq = va_arg(vl, char *);
	int dqlen = va_arg(vl, size_t);
	// calc QP via Q and P
//	char *inv = va_arg(vl, char *);
//	int invlen = va_arg(vl, size_t);	
	
	rsa_init(&cp->ctx, RSA_PKCS_V15, 0);
	
	cp->ctx.len = modlen; // size(N) in bytes
	mpi_read_binary(&cp->ctx.N,  (const unsigned char *)mod, modlen);
	mpi_read_binary(&cp->ctx.E,  (const unsigned char *)exp, explen);

	mpi_read_binary(&cp->ctx.D,  (const unsigned char *)d, dlen);
	mpi_read_binary(&cp->ctx.P,  (const unsigned char *)p, plen);
	mpi_read_binary(&cp->ctx.Q,  (const unsigned char *)q, qlen);
	mpi_read_binary(&cp->ctx.DP, (const unsigned char *)dp, dplen);
	mpi_read_binary(&cp->ctx.DQ, (const unsigned char *)dq, dqlen);
	mpi_inv_mod(&cp->ctx.QP, &cp->ctx.Q, &cp->ctx.P);
	
	int res = rsa_check_privkey(&cp->ctx);
	if(res != 0) {
		fprintf(stderr, "PolarSSL private key error res=%x exp=%d mod=%d.\n", res * -1, explen, modlen);
		return NULL;
	}

	return &cp->cp;
}

static int myrand(void *rng_state, unsigned char *output, size_t len) {
    size_t i;

    if(rng_state != NULL)
        rng_state = NULL;

    for( i = 0; i < len; ++i )
        output[i] = rand();
    
    return 0;
}


static struct crypto_pk *crypto_pk_polarssl_genkey_rsa(va_list vl)
{
	struct crypto_pk_polarssl *cp = malloc(sizeof(*cp));
	memset(cp, 0x00, sizeof(*cp));
	
	int transient = va_arg(vl, int);
	unsigned int nbits = va_arg(vl, unsigned int);
	unsigned int exp = va_arg(vl, unsigned int);

	if (transient) {
	}
	
	int res = rsa_gen_key(&cp->ctx, &myrand, NULL, nbits, exp);
	if (res) {
		fprintf(stderr, "PolarSSL private key generation error res=%x exp=%d nbits=%d.\n", res * -1, exp, nbits);
		return NULL;
	}
	
	return &cp->cp;
}

static void crypto_pk_polarssl_close(struct crypto_pk *_cp)
{
	struct crypto_pk_polarssl *cp = (struct crypto_pk_polarssl *)_cp;

	rsa_free(&cp->ctx);
	free(cp);
}

static unsigned char *crypto_pk_polarssl_encrypt(const struct crypto_pk *_cp, const unsigned char *buf, size_t len, size_t *clen)
{
	struct crypto_pk_polarssl *cp = (struct crypto_pk_polarssl *)_cp;
	int res;
	unsigned char *result;
	
	*clen = 0;
	size_t keylen = mpi_size(&cp->ctx.N);

	result = malloc(keylen);
	if (!result) {
		printf("RSA encrypt failed. Can't allocate result memory.\n");
		return NULL;
	}

	res = rsa_public(&cp->ctx, buf, result);
	if(res) {
		printf("RSA encrypt failed. Error: %x data len: %zu key len: %zu\n", res * -1, len, keylen);
		return NULL;
	}
	
	*clen = keylen;
	
	return result;
}

static unsigned char *crypto_pk_polarssl_decrypt(const struct crypto_pk *_cp, const unsigned char *buf, size_t len, size_t *clen)
{
	struct crypto_pk_polarssl *cp = (struct crypto_pk_polarssl *)_cp;
	int res;
	unsigned char *result;
	
	*clen = 0;
	size_t keylen = mpi_size(&cp->ctx.N);

	result = malloc(keylen);
	if (!result) {
		printf("RSA encrypt failed. Can't allocate result memory.\n");
		return NULL;
	}

	res = rsa_private(&cp->ctx, buf, result); // CHECK???
	if(res) {
		printf("RSA decrypt failed. Error: %x data len: %zu key len: %zu\n", res * -1, len, keylen);
		return NULL;
	}
	
	*clen = keylen;
	
	return result;
}

static size_t crypto_pk_polarssl_get_nbits(const struct crypto_pk *_cp)
{
	struct crypto_pk_polarssl *cp = (struct crypto_pk_polarssl *)_cp;

	return cp->ctx.len * 8;
return 0;
}

static unsigned char *crypto_pk_polarssl_get_parameter(const struct crypto_pk *_cp, unsigned param, size_t *plen)
{
	struct crypto_pk_polarssl *cp = (struct crypto_pk_polarssl *)_cp;
	unsigned char *result = NULL;
	switch(param){
		// mod
		case 0:
			*plen = mpi_size(&cp->ctx.N);
			result = malloc(*plen);
			memset(result, 0x00, *plen);
			mpi_write_binary(&cp->ctx.N, result, *plen);
			break;
		// exp
		case 1:
			*plen = mpi_size(&cp->ctx.E);
			result = malloc(*plen);
			memset(result, 0x00, *plen);
			mpi_write_binary(&cp->ctx.E, result, *plen);
			break;
		default:
			printf("Error get parameter. Param=%d", param);
			break;
	}
	
	return result;
}

static struct crypto_pk *crypto_pk_polarssl_open(enum crypto_algo_pk pk, va_list vl)
{
	struct crypto_pk *cp;

	if (pk == PK_RSA)
		cp = crypto_pk_polarssl_open_rsa(vl);
	else
		return NULL;

	cp->close = crypto_pk_polarssl_close;
	cp->encrypt = crypto_pk_polarssl_encrypt;
	cp->get_parameter = crypto_pk_polarssl_get_parameter;
	cp->get_nbits = crypto_pk_polarssl_get_nbits;

	return cp;
}

static struct crypto_pk *crypto_pk_polarssl_open_priv(enum crypto_algo_pk pk, va_list vl)
{
	struct crypto_pk *cp;

	if (pk == PK_RSA)
		cp = crypto_pk_polarssl_open_priv_rsa(vl);
	else
		return NULL;

	cp->close = crypto_pk_polarssl_close;
	cp->encrypt = crypto_pk_polarssl_encrypt;
	cp->decrypt = crypto_pk_polarssl_decrypt;
	cp->get_parameter = crypto_pk_polarssl_get_parameter;
	cp->get_nbits = crypto_pk_polarssl_get_nbits;

	return cp;
}

static struct crypto_pk *crypto_pk_polarssl_genkey(enum crypto_algo_pk pk, va_list vl)
{
	struct crypto_pk *cp;

	if (pk == PK_RSA)
		cp = crypto_pk_polarssl_genkey_rsa(vl);
	else
		return NULL;

	cp->close = crypto_pk_polarssl_close;
	cp->encrypt = crypto_pk_polarssl_encrypt;
	cp->decrypt = crypto_pk_polarssl_decrypt;
	cp->get_parameter = crypto_pk_polarssl_get_parameter;
	cp->get_nbits = crypto_pk_polarssl_get_nbits;

	return cp;
}

static struct crypto_backend crypto_polarssl_backend = {
	.hash_open = crypto_hash_polarssl_open,
	.pk_open = crypto_pk_polarssl_open,
	.pk_open_priv = crypto_pk_polarssl_open_priv,
	.pk_genkey = crypto_pk_polarssl_genkey,
};

struct crypto_backend *crypto_polarssl_init(void)
{
	return &crypto_polarssl_backend;
}