OVMS3-idf/components/esp32/hwcrypto/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 "hwcrypto/aes.h"
#include "soc/dport_reg.h"
#include "soc/hwcrypto_reg.h"
#include <sys/lock.h>
#include <freertos/FreeRTOS.h>
#include "soc/cpu.h"
#include <stdio.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;
void esp_aes_acquire_hardware( void )
{
/* newlib locks lazy initialize on ESP-IDF */
portENTER_CRITICAL(&aes_spinlock);
DPORT_STALL_OTHER_CPU_START();
{
/* Enable AES hardware */
_DPORT_REG_SET_BIT(DPORT_PERI_CLK_EN_REG, DPORT_PERI_EN_AES);
/* Clear reset on digital signature & secure boot units,
otherwise AES unit is held in reset also. */
_DPORT_REG_CLR_BIT(DPORT_PERI_RST_EN_REG,
DPORT_PERI_EN_AES
| DPORT_PERI_EN_DIGITAL_SIGNATURE
| DPORT_PERI_EN_SECUREBOOT);
}
DPORT_STALL_OTHER_CPU_END();
}
void esp_aes_release_hardware( void )
{
DPORT_STALL_OTHER_CPU_START();
{
/* Disable AES hardware */
_DPORT_REG_SET_BIT(DPORT_PERI_RST_EN_REG, DPORT_PERI_EN_AES);
/* Don't return other units to reset, as this pulls
reset on RSA & SHA units, respectively. */
_DPORT_REG_CLR_BIT(DPORT_PERI_CLK_EN_REG, DPORT_PERI_EN_AES);
}
DPORT_STALL_OTHER_CPU_END();
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);
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 inline 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;
memcpy((uint32_t *)AES_KEY_BASE, ctx->key, ctx->key_bytes);
DPORT_REG_WRITE(AES_MODE_REG, mode_reg_base + ((ctx->key_bytes / 8) - 2));
}
/* Run a single 16 byte block of AES, using the hardware engine.
*
* Call only while holding esp_aes_acquire_hardware().
*/
static inline void esp_aes_block(const void *input, void *output)
{
const uint32_t *input_words = (const uint32_t *)input;
uint32_t *output_words = (uint32_t *)output;
uint32_t *mem_block = (uint32_t *)AES_TEXT_BASE;
for(int i = 0; i < 4; i++) {
mem_block[i] = input_words[i];
}
DPORT_REG_WRITE(AES_START_REG, 1);
DPORT_STALL_OTHER_CPU_START();
{
while (_DPORT_REG_READ(AES_IDLE_REG) != 1) { }
for (int i = 0; i < 4; i++) {
output_words[i] = mem_block[i];
}
}
DPORT_STALL_OTHER_CPU_END();
}
/*
* AES-ECB block encryption
*/
void esp_aes_encrypt( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
esp_aes_block(input, output);
esp_aes_release_hardware();
}
/*
* AES-ECB block decryption
*/
void esp_aes_decrypt( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT);
esp_aes_block(input, output);
esp_aes_release_hardware();
}
/*
* 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] )
{
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, mode);
esp_aes_block(input, output);
esp_aes_release_hardware();
return 0;
}
/*
* 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 );
}
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, mode);
if ( mode == ESP_AES_DECRYPT ) {
while ( length > 0 ) {
memcpy(temp, input_words, 16);
esp_aes_block(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(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;
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
if ( mode == ESP_AES_DECRYPT ) {
while ( length-- ) {
if ( n == 0 ) {
esp_aes_block(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(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];
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
while ( length-- ) {
memcpy( ov, iv, 16 );
esp_aes_block(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;
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
while ( length-- ) {
if ( n == 0 ) {
esp_aes_block(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;
}