esp-idf/components/mbedtls/port/esp32/aes.c

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/**
* \brief AES block cipher, ESP32 hardware accelerated version
* Based on mbedTLS FIPS-197 compliant version.
*
* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
* Additions Copyright (C) 2016-2017, Espressif Systems (Shanghai) PTE Ltd
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
/*
* The AES block cipher was designed by Vincent Rijmen and Joan Daemen.
*
* http://csrc.nist.gov/encryption/aes/rijndael/Rijndael.pdf
* http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
*/
#include <string.h>
#include "mbedtls/aes.h"
#include "mbedtls/platform_util.h"
2019-03-25 02:15:14 -04:00
#include "esp32/aes.h"
#include "soc/hwcrypto_periph.h"
#include <sys/lock.h>
#include <freertos/FreeRTOS.h>
#include "soc/cpu.h"
#include <stdio.h>
#include "driver/periph_ctrl.h"
/* AES uses a spinlock mux not a lock as the underlying block operation
only takes 208 cycles (to write key & compute block), +600 cycles
for DPORT protection but +3400 cycles again if you use a full sized lock.
For CBC, CFB, etc. this may mean that interrupts are disabled for a longer
period of time for bigger lengths. However at the moment this has to happen
anyway due to DPORT protection...
*/
static portMUX_TYPE aes_spinlock = portMUX_INITIALIZER_UNLOCKED;
static inline bool valid_key_length(const esp_aes_context *ctx)
{
return ctx->key_bytes == 128/8 || ctx->key_bytes == 192/8 || ctx->key_bytes == 256/8;
}
void esp_aes_acquire_hardware( void )
{
portENTER_CRITICAL(&aes_spinlock);
/* Enable AES hardware */
periph_module_enable(PERIPH_AES_MODULE);
}
void esp_aes_release_hardware( void )
{
/* Disable AES hardware */
periph_module_disable(PERIPH_AES_MODULE);
portEXIT_CRITICAL(&aes_spinlock);
}
void esp_aes_init( esp_aes_context *ctx )
{
bzero( ctx, sizeof( esp_aes_context ) );
}
void esp_aes_free( esp_aes_context *ctx )
{
if ( ctx == NULL ) {
return;
}
bzero( ctx, sizeof( esp_aes_context ) );
}
/*
* AES key schedule (same for encryption or decryption, as hardware handles schedule)
*
*/
int esp_aes_setkey( esp_aes_context *ctx, const unsigned char *key,
unsigned int keybits )
{
if (keybits != 128 && keybits != 192 && keybits != 256) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
ctx->key_bytes = keybits / 8;
memcpy(ctx->key, key, ctx->key_bytes);
ctx->key_in_hardware = 0;
return 0;
}
/*
* Helper function to copy key from esp_aes_context buffer
* to hardware key registers.
*
* Call only while holding esp_aes_acquire_hardware().
*/
static void esp_aes_setkey_hardware(esp_aes_context *ctx, int mode)
{
const uint32_t MODE_DECRYPT_BIT = 4;
unsigned mode_reg_base = (mode == ESP_AES_ENCRYPT) ? 0 : MODE_DECRYPT_BIT;
ctx->key_in_hardware = 0;
for (int i = 0; i < ctx->key_bytes/4; ++i) {
DPORT_REG_WRITE(AES_KEY_BASE + i * 4, *(((uint32_t *)ctx->key) + i));
ctx->key_in_hardware += 4;
}
DPORT_REG_WRITE(AES_MODE_REG, mode_reg_base + ((ctx->key_bytes / 8) - 2));
/* Fault injection check: all words of key data should have been written to hardware */
if (ctx->key_in_hardware < 16
|| ctx->key_in_hardware != ctx->key_bytes) {
abort();
}
}
/* Run a single 16 byte block of AES, using the hardware engine.
*
* Call only while holding esp_aes_acquire_hardware().
*/
static int esp_aes_block(esp_aes_context *ctx, const void *input, void *output)
{
const uint32_t *input_words = (const uint32_t *)input;
uint32_t i0, i1, i2, i3;
uint32_t *output_words = (uint32_t *)output;
/* If no key is written to hardware yet, either the user hasn't called
mbedtls_aes_setkey_enc/mbedtls_aes_setkey_dec - meaning we also don't
know which mode to use - or a fault skipped the
key write to hardware. Treat this as a fatal error and zero the output block.
*/
if (ctx->key_in_hardware != ctx->key_bytes) {
bzero(output, 16);
return MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH;
}
/* Storing i0,i1,i2,i3 in registers not an array
helps a lot with optimisations at -Os level */
i0 = input_words[0];
DPORT_REG_WRITE(AES_TEXT_BASE, i0);
i1 = input_words[1];
DPORT_REG_WRITE(AES_TEXT_BASE + 4, i1);
i2 = input_words[2];
DPORT_REG_WRITE(AES_TEXT_BASE + 8, i2);
i3 = input_words[3];
DPORT_REG_WRITE(AES_TEXT_BASE + 12, i3);
DPORT_REG_WRITE(AES_START_REG, 1);
while (DPORT_REG_READ(AES_IDLE_REG) != 1) { }
esp_dport_access_read_buffer(output_words, AES_TEXT_BASE, 4);
/* Physical security check: Verify the AES accelerator actually ran, and wasn't
skipped due to external fault injection while starting the peripheral.
Note that i0,i1,i2,i3 are copied from input buffer in case input==output.
Bypassing this check requires at least one additional fault.
*/
if(i0 == output_words[0] && i1 == output_words[1] && i2 == output_words[2] && i3 == output_words[3]) {
// calling zeroing functions to narrow the
// window for a double-fault of the abort step, here
memset(output, 0, 16);
mbedtls_platform_zeroize(output, 16);
abort();
}
return 0;
}
/*
* AES-ECB block encryption
*/
int esp_internal_aes_encrypt( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
int r;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
r = esp_aes_block(ctx, input, output);
esp_aes_release_hardware();
return r;
}
/*
* AES-ECB block decryption
*/
int esp_internal_aes_decrypt( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
int r;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT);
r = esp_aes_block(ctx, input, output);
esp_aes_release_hardware();
return r;
}
/*
* AES-ECB block encryption/decryption
*/
int esp_aes_crypt_ecb( esp_aes_context *ctx,
int mode,
const unsigned char input[16],
unsigned char output[16] )
{
int r;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, mode);
r = esp_aes_block(ctx, input, output);
esp_aes_release_hardware();
return r;
}
/*
* AES-CBC buffer encryption/decryption
*/
int esp_aes_crypt_cbc( esp_aes_context *ctx,
int mode,
size_t length,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
{
int i;
uint32_t *output_words = (uint32_t *)output;
const uint32_t *input_words = (const uint32_t *)input;
uint32_t *iv_words = (uint32_t *)iv;
unsigned char temp[16];
if ( length % 16 ) {
return ( ERR_ESP_AES_INVALID_INPUT_LENGTH );
}
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, mode);
if ( mode == ESP_AES_DECRYPT ) {
while ( length > 0 ) {
memcpy(temp, input_words, 16);
esp_aes_block(ctx, input_words, output_words);
for ( i = 0; i < 4; i++ ) {
output_words[i] = output_words[i] ^ iv_words[i];
}
memcpy( iv_words, temp, 16 );
input_words += 4;
output_words += 4;
length -= 16;
}
} else { // ESP_AES_ENCRYPT
while ( length > 0 ) {
for ( i = 0; i < 4; i++ ) {
output_words[i] = input_words[i] ^ iv_words[i];
}
esp_aes_block(ctx, output_words, output_words);
memcpy( iv_words, output_words, 16 );
input_words += 4;
output_words += 4;
length -= 16;
}
}
esp_aes_release_hardware();
return 0;
}
/*
* AES-CFB128 buffer encryption/decryption
*/
int esp_aes_crypt_cfb128( esp_aes_context *ctx,
int mode,
size_t length,
size_t *iv_off,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
{
int c;
size_t n = *iv_off;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
if ( mode == ESP_AES_DECRYPT ) {
while ( length-- ) {
if ( n == 0 ) {
esp_aes_block(ctx, iv, iv);
}
c = *input++;
*output++ = (unsigned char)( c ^ iv[n] );
iv[n] = (unsigned char) c;
n = ( n + 1 ) & 0x0F;
}
} else {
while ( length-- ) {
if ( n == 0 ) {
esp_aes_block(ctx, iv, iv);
}
iv[n] = *output++ = (unsigned char)( iv[n] ^ *input++ );
n = ( n + 1 ) & 0x0F;
}
}
*iv_off = n;
esp_aes_release_hardware();
return 0;
}
/*
* AES-CFB8 buffer encryption/decryption
*/
int esp_aes_crypt_cfb8( esp_aes_context *ctx,
int mode,
size_t length,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
{
unsigned char c;
unsigned char ov[17];
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
while ( length-- ) {
memcpy( ov, iv, 16 );
esp_aes_block(ctx, iv, iv);
if ( mode == ESP_AES_DECRYPT ) {
ov[16] = *input;
}
c = *output++ = (unsigned char)( iv[0] ^ *input++ );
if ( mode == ESP_AES_ENCRYPT ) {
ov[16] = c;
}
memcpy( iv, ov + 1, 16 );
}
esp_aes_release_hardware();
return 0;
}
/*
* AES-CTR buffer encryption/decryption
*/
int esp_aes_crypt_ctr( esp_aes_context *ctx,
size_t length,
size_t *nc_off,
unsigned char nonce_counter[16],
unsigned char stream_block[16],
const unsigned char *input,
unsigned char *output )
{
int c, i;
size_t n = *nc_off;
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
ctx->key_in_hardware = 0;
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
while ( length-- ) {
if ( n == 0 ) {
esp_aes_block(ctx, nonce_counter, stream_block);
for ( i = 16; i > 0; i-- )
if ( ++nonce_counter[i - 1] != 0 ) {
break;
}
}
c = *input++;
*output++ = (unsigned char)( c ^ stream_block[n] );
n = ( n + 1 ) & 0x0F;
}
*nc_off = n;
esp_aes_release_hardware();
return 0;
}
/*
* AES-OFB (Output Feedback Mode) buffer encryption/decryption
*/
int esp_aes_crypt_ofb( esp_aes_context *ctx,
size_t length,
size_t *iv_off,
unsigned char iv[16],
const unsigned char *input,
unsigned char *output )
{
int ret = 0;
size_t n;
if ( ctx == NULL || iv_off == NULL || iv == NULL ||
input == NULL || output == NULL ) {
return MBEDTLS_ERR_AES_BAD_INPUT_DATA;
}
n = *iv_off;
if( n > 15 ) {
return( MBEDTLS_ERR_AES_BAD_INPUT_DATA );
}
if (!valid_key_length(ctx)) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
while( length-- ) {
if( n == 0 ) {
esp_aes_block(ctx, iv, iv);
}
*output++ = *input++ ^ iv[n];
n = ( n + 1 ) & 0x0F;
}
*iv_off = n;
esp_aes_release_hardware();
return( ret );
}