contiki/cpu/cc2538/dev/aes.c
Benoît Thébaudeau e8a268cd15 cc2538: aes: Add support for 192- and 256-bit keys
Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau.dev@gmail.com>
2015-06-02 21:41:56 +02:00

153 lines
5.3 KiB
C

/*
* Original file:
* Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
* All rights reserved.
*
* Port to Contiki:
* Copyright (c) 2013, ADVANSEE - http://www.advansee.com/
* 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 copyright holder 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDER 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.
*/
/**
* \addtogroup cc2538-aes
* @{
*
* \file
* Implementation of the cc2538 AES driver
*/
#include "contiki.h"
#include "dev/rom-util.h"
#include "dev/aes.h"
#include "reg.h"
#include <stdint.h>
/*---------------------------------------------------------------------------*/
uint8_t
aes_load_keys(const void *keys, uint8_t key_size, uint8_t count,
uint8_t start_area)
{
uint32_t aes_key_store_size;
uint32_t areas;
uint64_t aligned_keys[16];
int i;
if(REG(AES_CTRL_ALG_SEL) != 0x00000000) {
return CRYPTO_RESOURCE_IN_USE;
}
/* 192-bit keys must be padded to 256 bits */
if(key_size == AES_KEY_STORE_SIZE_KEY_SIZE_192) {
for(i = 0; i < count; i++) {
rom_util_memcpy(&aligned_keys[i << 2], &((uint64_t *)keys)[i * 3], 24);
aligned_keys[(i << 2) + 3] = 0;
}
}
/* Change count to the number of 128-bit key areas */
if(key_size != AES_KEY_STORE_SIZE_KEY_SIZE_128) {
count <<= 1;
}
/* The keys base address needs to be 4-byte aligned */
if(key_size != AES_KEY_STORE_SIZE_KEY_SIZE_192) {
rom_util_memcpy(aligned_keys, keys, count << 4);
}
/* Workaround for AES registers not retained after PM2 */
REG(AES_CTRL_INT_CFG) = AES_CTRL_INT_CFG_LEVEL;
REG(AES_CTRL_INT_EN) = AES_CTRL_INT_EN_DMA_IN_DONE |
AES_CTRL_INT_EN_RESULT_AV;
/* Configure master control module */
REG(AES_CTRL_ALG_SEL) = AES_CTRL_ALG_SEL_KEYSTORE;
/* Clear any outstanding events */
REG(AES_CTRL_INT_CLR) = AES_CTRL_INT_CLR_DMA_IN_DONE |
AES_CTRL_INT_CLR_RESULT_AV;
/* Configure key store module (areas, size)
* Note that writing AES_KEY_STORE_SIZE deletes all stored keys */
aes_key_store_size = REG(AES_KEY_STORE_SIZE);
if((aes_key_store_size & AES_KEY_STORE_SIZE_KEY_SIZE_M) != key_size) {
REG(AES_KEY_STORE_SIZE) = (aes_key_store_size &
~AES_KEY_STORE_SIZE_KEY_SIZE_M) | key_size;
}
/* Free possibly already occupied key areas */
areas = ((0x00000001 << count) - 1) << start_area;
REG(AES_KEY_STORE_WRITTEN_AREA) = areas;
/* Enable key areas to write */
REG(AES_KEY_STORE_WRITE_AREA) = areas;
/* Configure DMAC
* Enable DMA channel 0 */
REG(AES_DMAC_CH0_CTRL) = AES_DMAC_CH_CTRL_EN;
/* Base address of the keys in ext. memory */
REG(AES_DMAC_CH0_EXTADDR) = (uint32_t)aligned_keys;
/* Total keys length in bytes (e.g. 16 for 1 x 128-bit key) */
REG(AES_DMAC_CH0_DMALENGTH) = (REG(AES_DMAC_CH0_DMALENGTH) &
~AES_DMAC_CH_DMALENGTH_DMALEN_M) |
(count << (4 + AES_DMAC_CH_DMALENGTH_DMALEN_S));
/* Wait for operation to complete */
while(!(REG(AES_CTRL_INT_STAT) & AES_CTRL_INT_STAT_RESULT_AV));
/* Check for absence of errors in DMA and key store */
if(REG(AES_CTRL_INT_STAT) & AES_CTRL_INT_STAT_DMA_BUS_ERR) {
REG(AES_CTRL_INT_CLR) = AES_CTRL_INT_CLR_DMA_BUS_ERR;
/* Disable master control / DMA clock */
REG(AES_CTRL_ALG_SEL) = 0x00000000;
return CRYPTO_DMA_BUS_ERROR;
}
if(REG(AES_CTRL_INT_STAT) & AES_CTRL_INT_STAT_KEY_ST_WR_ERR) {
REG(AES_CTRL_INT_CLR) = AES_CTRL_INT_CLR_KEY_ST_WR_ERR;
/* Disable master control / DMA clock */
REG(AES_CTRL_ALG_SEL) = 0x00000000;
return AES_KEYSTORE_WRITE_ERROR;
}
/* Acknowledge the interrupt */
REG(AES_CTRL_INT_CLR) = AES_CTRL_INT_CLR_DMA_IN_DONE |
AES_CTRL_INT_CLR_RESULT_AV;
/* Disable master control / DMA clock */
REG(AES_CTRL_ALG_SEL) = 0x00000000;
/* Check status, if error return error code */
if((REG(AES_KEY_STORE_WRITTEN_AREA) & areas) != areas) {
return AES_KEYSTORE_WRITE_ERROR;
}
return CRYPTO_SUCCESS;
}
/** @} */