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