contiki/core/dev/cc2420-aes.c

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/*
* Copyright (c) 2008, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
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* $Id: cc2420-aes.c,v 1.5 2010/06/24 11:25:55 nifi Exp $
*/
/**
* \file
* AES encryption functions.
* \author
* Adam Dunkels <adam@sics.se>
*/
#include "contiki.h"
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#include "dev/cc2420.h"
#include "dev/cc2420-aes.h"
#include "dev/spi.h"
#define KEYLEN 16
#define MAX_DATALEN 16
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#define CC2420_WRITE_RAM_REV(buffer,adr,count) \
do { \
uint8_t i; \
CC2420_SPI_ENABLE(); \
SPI_WRITE_FAST(0x80 | (adr & 0x7f)); \
SPI_WRITE_FAST((adr >> 1) & 0xc0); \
for(i = (count); i > 0; i--) { \
SPI_WRITE_FAST(((uint8_t*)(buffer))[i - 1]); \
} \
SPI_WAITFORTx_ENDED(); \
CC2420_SPI_DISABLE(); \
} while(0)
#define MIN(a,b) ((a) < (b)? (a): (b))
/*---------------------------------------------------------------------------*/
void
cc2420_aes_set_key(const uint8_t *key, int index)
{
switch(index) {
case 0:
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CC2420_WRITE_RAM_REV(key, CC2420RAM_KEY0, KEYLEN);
break;
case 1:
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CC2420_WRITE_RAM_REV(key, CC2420RAM_KEY1, KEYLEN);
break;
}
}
/*---------------------------------------------------------------------------*/
/* Encrypt at most 16 bytes of data. */
static void
cipher16(uint8_t *data, int len)
{
uint8_t status;
len = MIN(len, MAX_DATALEN);
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CC2420_WRITE_RAM(data, CC2420RAM_SABUF, len);
CC2420_STROBE(CC2420_SAES);
/* Wait for the encryption to finish */
do {
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CC2420_GET_STATUS(status);
} while(status & BV(CC2420_ENC_BUSY));
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CC2420_READ_RAM(data, CC2420RAM_SABUF, len);
}
/*---------------------------------------------------------------------------*/
void
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cc2420_aes_cipher(uint8_t *data, int len, int key_index)
{
int i;
uint16_t secctrl0;
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CC2420_READ_REG(CC2420_SECCTRL0, secctrl0);
secctrl0 &= ~(CC2420_SECCTRL0_SAKEYSEL0 | CC2420_SECCTRL0_SAKEYSEL1);
switch(key_index) {
case 0:
secctrl0 |= CC2420_SECCTRL0_SAKEYSEL0;
break;
case 1:
secctrl0 |= CC2420_SECCTRL0_SAKEYSEL1;
break;
}
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CC2420_WRITE_REG(CC2420_SECCTRL0, secctrl0);
for(i = 0; i < len; i = i + MAX_DATALEN) {
cipher16(data + i, MIN(len - i, MAX_DATALEN));
}
}
/*---------------------------------------------------------------------------*/