libfreefare/libfreefare/mifare_desfire_key.c

/*-
 * Copyright (C) 2010, Romain Tartiere.
 *
 * This program 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 3 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.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

#include <stdlib.h>
#include <string.h>

#include <openssl/des.h>

#include <freefare.h>
#include "freefare_internal.h"

static inline void update_key_schedules(MifareDESFireKey key);

static inline void
update_key_schedules(MifareDESFireKey key)
{
    DES_set_key((DES_cblock *)key->data, &(key->ks1));
    DES_set_key((DES_cblock *)(key->data + 8), &(key->ks2));
    if (T_3K3DES == key->type) {
	DES_set_key((DES_cblock *)(key->data + 16), &(key->ks3));
    }
}

MifareDESFireKey
mifare_desfire_des_key_new(const uint8_t value[8])
{
    uint8_t data[8];
    memcpy(data, value, 8);
    for (int n = 0; n < 8; n++)
	data[n] &= 0xfe;
    return mifare_desfire_des_key_new_with_version(data);
}

MifareDESFireKey
mifare_desfire_des_key_new_with_version(const uint8_t value[8])
{
    MifareDESFireKey key;

    if ((key = malloc(sizeof(struct mifare_desfire_key)))) {
	key->type = T_DES;
	memcpy(key->data, value, 8);
	memcpy(key->data + 8, value, 8);
	update_key_schedules(key);
    }
    return key;
}

MifareDESFireKey
mifare_desfire_3des_key_new(const uint8_t value[16])
{
    uint8_t data[16];
    memcpy(data, value, 16);
    for (int n = 0; n < 8; n++)
	data[n] &= 0xfe;
    for (int n = 8; n < 16; n++)
	data[n] |= 0x01;
    return mifare_desfire_3des_key_new_with_version(data);
}

MifareDESFireKey
mifare_desfire_3des_key_new_with_version(const uint8_t value[16])
{
    MifareDESFireKey key;

    if ((key = malloc(sizeof(struct mifare_desfire_key)))) {
	key->type = T_3DES;
	memcpy(key->data, value, 16);
	update_key_schedules(key);
    }
    return key;
}

MifareDESFireKey
mifare_desfire_3k3des_key_new(const uint8_t value[24])
{
    uint8_t data[24];
    memcpy(data, value, 24);
    for (int n = 0; n < 8; n++)
	data[n] &= 0xfe;
    return mifare_desfire_3k3des_key_new_with_version(data);
}

MifareDESFireKey
mifare_desfire_3k3des_key_new_with_version(const uint8_t value[24])
{
    MifareDESFireKey key;

    if ((key = malloc(sizeof(struct mifare_desfire_key)))) {
	key->type = T_3K3DES;
	memcpy(key->data, value, 24);
	update_key_schedules(key);
    }
    return key;
}

MifareDESFireKey
mifare_desfire_aes_key_new(const uint8_t value[16])
{
    return mifare_desfire_aes_key_new_with_version(value, 0);
}

MifareDESFireKey
mifare_desfire_aes_key_new_with_version(const uint8_t value[16], uint8_t version)
{
    MifareDESFireKey key;

    if ((key = malloc(sizeof(struct mifare_desfire_key)))) {
	memcpy(key->data, value, 16);
	key->type = T_AES;
	key->aes_version = version;
    }
    return key;
}

uint8_t
mifare_desfire_key_get_version(MifareDESFireKey key)
{
    uint8_t version = 0;

    for (int n = 0; n < 8; n++) {
	version |= ((key->data[n] & 1) << (7 - n));
    }

    return version;
}

void
mifare_desfire_key_set_version(MifareDESFireKey key, uint8_t version)
{
    for (int n = 0; n < 8; n++) {
	uint8_t version_bit = ((version & (1 << (7 - n))) >> (7 - n));
	key->data[n] &= 0xfe;
	key->data[n] |= version_bit;
	if (key->type == T_DES) {
	    key->data[n + 8] = key->data[n];
	} else {
	    // Write ~version to avoid turning a 3DES key into a DES key
	    key->data[n + 8] &= 0xfe;
	    key->data[n + 8] |= ~version_bit;
	}
    }
}

MifareDESFireKey
mifare_desfire_session_key_new(const uint8_t rnda[], const uint8_t rndb[], MifareDESFireKey authentication_key)
{
    MifareDESFireKey key = NULL;

    uint8_t buffer[24];

    switch (authentication_key->type) {
    case T_DES:
	memcpy(buffer, rnda, 4);
	memcpy(buffer + 4, rndb, 4);
	key = mifare_desfire_des_key_new_with_version(buffer);
	break;
    case T_3DES:
	memcpy(buffer, rnda, 4);
	memcpy(buffer + 4, rndb, 4);
	memcpy(buffer + 8, rnda + 4, 4);
	memcpy(buffer + 12, rndb + 4, 4);
	key = mifare_desfire_3des_key_new_with_version(buffer);
	break;
    case T_3K3DES:
	memcpy(buffer, rnda, 4);
	memcpy(buffer + 4, rndb, 4);
	memcpy(buffer + 8, rnda + 6, 4);
	memcpy(buffer + 12, rndb + 6, 4);
	memcpy(buffer + 16, rnda + 12, 4);
	memcpy(buffer + 20, rndb + 12, 4);
	key = mifare_desfire_3k3des_key_new(buffer);
	break;
    case T_AES:
	memcpy(buffer, rnda, 4);
	memcpy(buffer + 4, rndb, 4);
	memcpy(buffer + 8, rnda + 12, 4);
	memcpy(buffer + 12, rndb + 12, 4);
	key = mifare_desfire_aes_key_new(buffer);
	break;
    }

    return key;
}

void
mifare_desfire_key_free(MifareDESFireKey key)
{
    free(key);
}