721 lines
20 KiB
C
721 lines
20 KiB
C
/**
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* \brief AES block cipher, ESP32 hardware accelerated version
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* Based on mbedTLS FIPS-197 compliant version.
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*
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* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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* Additions Copyright (C) 2016-2017, Espressif Systems (Shanghai) PTE Ltd
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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/*
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* The AES block cipher was designed by Vincent Rijmen and Joan Daemen.
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*
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* http://csrc.nist.gov/encryption/aes/rijndael/Rijndael.pdf
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* http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
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*/
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#include <string.h>
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#include "mbedtls/aes.h"
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#include "hwcrypto/aes.h"
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#include "mbedtls/platform_util.h"
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#include "soc/dport_reg.h"
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#include "soc/hwcrypto_reg.h"
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#include <sys/lock.h>
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#include <freertos/FreeRTOS.h>
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#include "soc/cpu.h"
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#include <stdio.h>
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#include "driver/periph_ctrl.h"
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/* AES uses a spinlock mux not a lock as the underlying block operation
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only takes 208 cycles (to write key & compute block), +600 cycles
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for DPORT protection but +3400 cycles again if you use a full sized lock.
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For CBC, CFB, etc. this may mean that interrupts are disabled for a longer
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period of time for bigger lengths. However at the moment this has to happen
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anyway due to DPORT protection...
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*/
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static portMUX_TYPE aes_spinlock = portMUX_INITIALIZER_UNLOCKED;
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static inline bool valid_key_length(const esp_aes_context *ctx)
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{
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return ctx->key_bytes == 128/8 || ctx->key_bytes == 192/8 || ctx->key_bytes == 256/8;
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}
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void esp_aes_acquire_hardware( void )
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{
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portENTER_CRITICAL(&aes_spinlock);
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/* Enable AES hardware */
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periph_module_enable(PERIPH_AES_MODULE);
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}
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void esp_aes_release_hardware( void )
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{
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/* Disable AES hardware */
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periph_module_disable(PERIPH_AES_MODULE);
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portEXIT_CRITICAL(&aes_spinlock);
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}
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void esp_aes_init( esp_aes_context *ctx )
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{
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bzero( ctx, sizeof( esp_aes_context ) );
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}
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void esp_aes_free( esp_aes_context *ctx )
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{
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if ( ctx == NULL ) {
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return;
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}
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bzero( ctx, sizeof( esp_aes_context ) );
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}
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/*
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* AES key schedule (same for encryption or decryption, as hardware handles schedule)
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*
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*/
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int esp_aes_setkey( esp_aes_context *ctx, const unsigned char *key,
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unsigned int keybits )
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{
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if (keybits != 128 && keybits != 192 && keybits != 256) {
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return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
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}
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ctx->key_bytes = keybits / 8;
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memcpy(ctx->key, key, ctx->key_bytes);
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ctx->key_in_hardware = 0;
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return 0;
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}
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/*
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* Helper function to copy key from esp_aes_context buffer
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* to hardware key registers.
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*
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* Call only while holding esp_aes_acquire_hardware().
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*/
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static void esp_aes_setkey_hardware(esp_aes_context *ctx, int mode)
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{
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const uint32_t MODE_DECRYPT_BIT = 4;
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unsigned mode_reg_base = (mode == ESP_AES_ENCRYPT) ? 0 : MODE_DECRYPT_BIT;
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ctx->key_in_hardware = 0;
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for (int i = 0; i < ctx->key_bytes/4; ++i) {
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DPORT_REG_WRITE(AES_KEY_BASE + i * 4, *(((uint32_t *)ctx->key) + i));
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ctx->key_in_hardware += 4;
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}
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DPORT_REG_WRITE(AES_MODE_REG, mode_reg_base + ((ctx->key_bytes / 8) - 2));
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/* Fault injection check: all words of key data should have been written to hardware */
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if (ctx->key_in_hardware < 16
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|| ctx->key_in_hardware != ctx->key_bytes) {
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abort();
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}
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}
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/* Run a single 16 byte block of AES, using the hardware engine.
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*
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* Call only while holding esp_aes_acquire_hardware().
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*/
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static int esp_aes_block(esp_aes_context *ctx, const void *input, void *output)
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{
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const uint32_t *input_words = (const uint32_t *)input;
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uint32_t i0, i1, i2, i3;
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uint32_t *output_words = (uint32_t *)output;
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/* If no key is written to hardware yet, either the user hasn't called
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mbedtls_aes_setkey_enc/mbedtls_aes_setkey_dec - meaning we also don't
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know which mode to use - or a fault skipped the
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key write to hardware. Treat this as a fatal error and zero the output block.
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*/
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if (ctx->key_in_hardware != ctx->key_bytes) {
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bzero(output, 16);
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return MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH;
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}
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/* Storing i0,i1,i2,i3 in registers not an array
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helps a lot with optimisations at -Os level */
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i0 = input_words[0];
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DPORT_REG_WRITE(AES_TEXT_BASE, i0);
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i1 = input_words[1];
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DPORT_REG_WRITE(AES_TEXT_BASE + 4, i1);
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i2 = input_words[2];
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DPORT_REG_WRITE(AES_TEXT_BASE + 8, i2);
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i3 = input_words[3];
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DPORT_REG_WRITE(AES_TEXT_BASE + 12, i3);
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DPORT_REG_WRITE(AES_START_REG, 1);
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while (DPORT_REG_READ(AES_IDLE_REG) != 1) { }
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esp_dport_access_read_buffer(output_words, AES_TEXT_BASE, 4);
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/* Physical security check: Verify the AES accelerator actually ran, and wasn't
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skipped due to external fault injection while starting the peripheral.
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Note that i0,i1,i2,i3 are copied from input buffer in case input==output.
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Bypassing this check requires at least one additional fault.
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*/
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if(i0 == output_words[0] && i1 == output_words[1] && i2 == output_words[2] && i3 == output_words[3]) {
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// calling zeroing functions to narrow the
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// window for a double-fault of the abort step, here
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memset(output, 0, 16);
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mbedtls_platform_zeroize(output, 16);
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abort();
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}
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return 0;
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}
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/*
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* AES-ECB block encryption
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*/
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int esp_internal_aes_encrypt( esp_aes_context *ctx,
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const unsigned char input[16],
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unsigned char output[16] )
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{
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int r;
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if (!valid_key_length(ctx)) {
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return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
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}
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esp_aes_acquire_hardware();
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ctx->key_in_hardware = 0;
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esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
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r = esp_aes_block(ctx, input, output);
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esp_aes_release_hardware();
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return r;
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}
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void esp_aes_encrypt( esp_aes_context *ctx,
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const unsigned char input[16],
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unsigned char output[16] )
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{
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esp_internal_aes_encrypt(ctx, input, output);
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}
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/*
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* AES-ECB block decryption
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*/
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int esp_internal_aes_decrypt( esp_aes_context *ctx,
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const unsigned char input[16],
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unsigned char output[16] )
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{
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int r;
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if (!valid_key_length(ctx)) {
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return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
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}
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esp_aes_acquire_hardware();
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ctx->key_in_hardware = 0;
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esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT);
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r = esp_aes_block(ctx, input, output);
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esp_aes_release_hardware();
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return r;
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}
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void esp_aes_decrypt( esp_aes_context *ctx,
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const unsigned char input[16],
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unsigned char output[16] )
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{
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esp_internal_aes_decrypt(ctx, input, output);
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}
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/*
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* AES-ECB block encryption/decryption
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*/
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int esp_aes_crypt_ecb( esp_aes_context *ctx,
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int mode,
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const unsigned char input[16],
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unsigned char output[16] )
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{
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int r;
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if (!valid_key_length(ctx)) {
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return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
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}
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esp_aes_acquire_hardware();
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ctx->key_in_hardware = 0;
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esp_aes_setkey_hardware(ctx, mode);
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r = esp_aes_block(ctx, input, output);
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esp_aes_release_hardware();
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return r;
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}
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/*
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* AES-CBC buffer encryption/decryption
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*/
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int esp_aes_crypt_cbc( esp_aes_context *ctx,
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int mode,
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size_t length,
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unsigned char iv[16],
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const unsigned char *input,
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unsigned char *output )
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{
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int i;
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uint32_t *output_words = (uint32_t *)output;
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const uint32_t *input_words = (const uint32_t *)input;
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uint32_t *iv_words = (uint32_t *)iv;
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unsigned char temp[16];
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if ( length % 16 ) {
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return ( ERR_ESP_AES_INVALID_INPUT_LENGTH );
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}
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if (!valid_key_length(ctx)) {
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return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
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}
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esp_aes_acquire_hardware();
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ctx->key_in_hardware = 0;
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esp_aes_setkey_hardware(ctx, mode);
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if ( mode == ESP_AES_DECRYPT ) {
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while ( length > 0 ) {
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memcpy(temp, input_words, 16);
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esp_aes_block(ctx, input_words, output_words);
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for ( i = 0; i < 4; i++ ) {
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output_words[i] = output_words[i] ^ iv_words[i];
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}
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memcpy( iv_words, temp, 16 );
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input_words += 4;
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output_words += 4;
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length -= 16;
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}
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} else { // ESP_AES_ENCRYPT
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while ( length > 0 ) {
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for ( i = 0; i < 4; i++ ) {
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output_words[i] = input_words[i] ^ iv_words[i];
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}
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esp_aes_block(ctx, output_words, output_words);
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memcpy( iv_words, output_words, 16 );
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input_words += 4;
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output_words += 4;
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length -= 16;
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}
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}
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esp_aes_release_hardware();
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return 0;
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}
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/*
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* AES-CFB128 buffer encryption/decryption
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*/
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int esp_aes_crypt_cfb128( esp_aes_context *ctx,
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int mode,
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size_t length,
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size_t *iv_off,
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unsigned char iv[16],
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const unsigned char *input,
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unsigned char *output )
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{
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int c;
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size_t n = *iv_off;
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if (!valid_key_length(ctx)) {
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return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
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}
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esp_aes_acquire_hardware();
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ctx->key_in_hardware = 0;
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esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
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if ( mode == ESP_AES_DECRYPT ) {
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while ( length-- ) {
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if ( n == 0 ) {
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esp_aes_block(ctx, iv, iv );
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}
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c = *input++;
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*output++ = (unsigned char)( c ^ iv[n] );
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iv[n] = (unsigned char) c;
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n = ( n + 1 ) & 0x0F;
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}
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} else {
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while ( length-- ) {
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if ( n == 0 ) {
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esp_aes_block(ctx, iv, iv );
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}
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iv[n] = *output++ = (unsigned char)( iv[n] ^ *input++ );
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n = ( n + 1 ) & 0x0F;
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}
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}
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*iv_off = n;
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esp_aes_release_hardware();
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return 0;
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}
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/*
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* AES-CFB8 buffer encryption/decryption
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*/
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int esp_aes_crypt_cfb8( esp_aes_context *ctx,
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int mode,
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size_t length,
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unsigned char iv[16],
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const unsigned char *input,
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unsigned char *output )
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{
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unsigned char c;
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unsigned char ov[17];
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if (!valid_key_length(ctx)) {
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return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
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}
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esp_aes_acquire_hardware();
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ctx->key_in_hardware = 0;
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esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
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while ( length-- ) {
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memcpy( ov, iv, 16 );
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esp_aes_block(ctx, iv, iv);
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if ( mode == ESP_AES_DECRYPT ) {
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ov[16] = *input;
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}
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c = *output++ = (unsigned char)( iv[0] ^ *input++ );
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if ( mode == ESP_AES_ENCRYPT ) {
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ov[16] = c;
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}
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memcpy( iv, ov + 1, 16 );
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}
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esp_aes_release_hardware();
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return 0;
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}
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/*
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* AES-CTR buffer encryption/decryption
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*/
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int esp_aes_crypt_ctr( esp_aes_context *ctx,
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size_t length,
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size_t *nc_off,
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unsigned char nonce_counter[16],
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unsigned char stream_block[16],
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const unsigned char *input,
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unsigned char *output )
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{
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int c, i;
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size_t n = *nc_off;
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if (!valid_key_length(ctx)) {
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return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
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}
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esp_aes_acquire_hardware();
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ctx->key_in_hardware = 0;
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esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT);
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while ( length-- ) {
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if ( n == 0 ) {
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esp_aes_block(ctx, nonce_counter, stream_block);
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for ( i = 16; i > 0; i-- )
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if ( ++nonce_counter[i - 1] != 0 ) {
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break;
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}
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}
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c = *input++;
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*output++ = (unsigned char)( c ^ stream_block[n] );
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n = ( n + 1 ) & 0x0F;
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}
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*nc_off = n;
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esp_aes_release_hardware();
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return 0;
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}
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/* Below XTS implementation is copied aes.c of mbedtls library.
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* When MBEDTLS_AES_ALT is defined mbedtls expects alternate
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* definition of XTS functions to be available. Even if this
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* could have been avoided, it is done for consistency reason.
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*/
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void esp_aes_xts_init( esp_aes_xts_context *ctx )
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{
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esp_aes_init( &ctx->crypt );
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esp_aes_init( &ctx->tweak );
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}
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void esp_aes_xts_free( esp_aes_xts_context *ctx )
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{
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esp_aes_free( &ctx->crypt );
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esp_aes_free( &ctx->tweak );
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}
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static int esp_aes_xts_decode_keys( const unsigned char *key,
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unsigned int keybits,
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const unsigned char **key1,
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unsigned int *key1bits,
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const unsigned char **key2,
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unsigned int *key2bits )
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{
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const unsigned int half_keybits = keybits / 2;
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const unsigned int half_keybytes = half_keybits / 8;
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switch( keybits )
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{
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case 256: break;
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case 512: break;
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default : return( MBEDTLS_ERR_AES_INVALID_KEY_LENGTH );
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}
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*key1bits = half_keybits;
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*key2bits = half_keybits;
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*key1 = &key[0];
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*key2 = &key[half_keybytes];
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return 0;
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}
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int esp_aes_xts_setkey_enc( esp_aes_xts_context *ctx,
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const unsigned char *key,
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unsigned int keybits)
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{
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int ret;
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const unsigned char *key1, *key2;
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unsigned int key1bits, key2bits;
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ret = esp_aes_xts_decode_keys( key, keybits, &key1, &key1bits,
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&key2, &key2bits );
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if( ret != 0 )
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return( ret );
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/* Set the tweak key. Always set tweak key for the encryption mode. */
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ret = esp_aes_setkey( &ctx->tweak, key2, key2bits );
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if( ret != 0 )
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return( ret );
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/* Set crypt key for encryption. */
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return esp_aes_setkey( &ctx->crypt, key1, key1bits );
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}
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|
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int esp_aes_xts_setkey_dec( esp_aes_xts_context *ctx,
|
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const unsigned char *key,
|
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unsigned int keybits)
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|
{
|
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int ret;
|
|
const unsigned char *key1, *key2;
|
|
unsigned int key1bits, key2bits;
|
|
|
|
ret = esp_aes_xts_decode_keys( key, keybits, &key1, &key1bits,
|
|
&key2, &key2bits );
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
/* Set the tweak key. Always set tweak key for encryption. */
|
|
ret = esp_aes_setkey( &ctx->tweak, key2, key2bits );
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
/* Set crypt key for decryption. */
|
|
return esp_aes_setkey( &ctx->crypt, key1, key1bits );
|
|
}
|
|
|
|
/* Endianess with 64 bits values */
|
|
#ifndef GET_UINT64_LE
|
|
#define GET_UINT64_LE(n,b,i) \
|
|
{ \
|
|
(n) = ( (uint64_t) (b)[(i) + 7] << 56 ) \
|
|
| ( (uint64_t) (b)[(i) + 6] << 48 ) \
|
|
| ( (uint64_t) (b)[(i) + 5] << 40 ) \
|
|
| ( (uint64_t) (b)[(i) + 4] << 32 ) \
|
|
| ( (uint64_t) (b)[(i) + 3] << 24 ) \
|
|
| ( (uint64_t) (b)[(i) + 2] << 16 ) \
|
|
| ( (uint64_t) (b)[(i) + 1] << 8 ) \
|
|
| ( (uint64_t) (b)[(i) ] ); \
|
|
}
|
|
#endif
|
|
|
|
#ifndef PUT_UINT64_LE
|
|
#define PUT_UINT64_LE(n,b,i) \
|
|
{ \
|
|
(b)[(i) + 7] = (unsigned char) ( (n) >> 56 ); \
|
|
(b)[(i) + 6] = (unsigned char) ( (n) >> 48 ); \
|
|
(b)[(i) + 5] = (unsigned char) ( (n) >> 40 ); \
|
|
(b)[(i) + 4] = (unsigned char) ( (n) >> 32 ); \
|
|
(b)[(i) + 3] = (unsigned char) ( (n) >> 24 ); \
|
|
(b)[(i) + 2] = (unsigned char) ( (n) >> 16 ); \
|
|
(b)[(i) + 1] = (unsigned char) ( (n) >> 8 ); \
|
|
(b)[(i) ] = (unsigned char) ( (n) ); \
|
|
}
|
|
#endif
|
|
|
|
typedef unsigned char esp_be128[16];
|
|
|
|
/*
|
|
* GF(2^128) multiplication function
|
|
*
|
|
* This function multiplies a field element by x in the polynomial field
|
|
* representation. It uses 64-bit word operations to gain speed but compensates
|
|
* for machine endianess and hence works correctly on both big and little
|
|
* endian machines.
|
|
*/
|
|
static void esp_gf128mul_x_ble( unsigned char r[16],
|
|
const unsigned char x[16] )
|
|
{
|
|
uint64_t a, b, ra, rb;
|
|
|
|
GET_UINT64_LE( a, x, 0 );
|
|
GET_UINT64_LE( b, x, 8 );
|
|
|
|
ra = ( a << 1 ) ^ 0x0087 >> ( 8 - ( ( b >> 63 ) << 3 ) );
|
|
rb = ( a >> 63 ) | ( b << 1 );
|
|
|
|
PUT_UINT64_LE( ra, r, 0 );
|
|
PUT_UINT64_LE( rb, r, 8 );
|
|
}
|
|
|
|
/*
|
|
* AES-XTS buffer encryption/decryption
|
|
*/
|
|
int esp_aes_crypt_xts( esp_aes_xts_context *ctx,
|
|
int mode,
|
|
size_t length,
|
|
const unsigned char data_unit[16],
|
|
const unsigned char *input,
|
|
unsigned char *output )
|
|
{
|
|
int ret;
|
|
size_t blocks = length / 16;
|
|
size_t leftover = length % 16;
|
|
unsigned char tweak[16];
|
|
unsigned char prev_tweak[16];
|
|
unsigned char tmp[16];
|
|
|
|
/* Sectors must be at least 16 bytes. */
|
|
if( length < 16 )
|
|
return MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH;
|
|
|
|
/* NIST SP 80-38E disallows data units larger than 2**20 blocks. */
|
|
if( length > ( 1 << 20 ) * 16 )
|
|
return MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH;
|
|
|
|
/* Compute the tweak. */
|
|
ret = esp_aes_crypt_ecb( &ctx->tweak, MBEDTLS_AES_ENCRYPT,
|
|
data_unit, tweak );
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
while( blocks-- )
|
|
{
|
|
size_t i;
|
|
|
|
if( leftover && ( mode == MBEDTLS_AES_DECRYPT ) && blocks == 0 )
|
|
{
|
|
/* We are on the last block in a decrypt operation that has
|
|
* leftover bytes, so we need to use the next tweak for this block,
|
|
* and this tweak for the lefover bytes. Save the current tweak for
|
|
* the leftovers and then update the current tweak for use on this,
|
|
* the last full block. */
|
|
memcpy( prev_tweak, tweak, sizeof( tweak ) );
|
|
esp_gf128mul_x_ble( tweak, tweak );
|
|
}
|
|
|
|
for( i = 0; i < 16; i++ )
|
|
tmp[i] = input[i] ^ tweak[i];
|
|
|
|
ret = esp_aes_crypt_ecb( &ctx->crypt, mode, tmp, tmp );
|
|
if( ret != 0 )
|
|
return( ret );
|
|
|
|
for( i = 0; i < 16; i++ )
|
|
output[i] = tmp[i] ^ tweak[i];
|
|
|
|
/* Update the tweak for the next block. */
|
|
esp_gf128mul_x_ble( tweak, tweak );
|
|
|
|
output += 16;
|
|
input += 16;
|
|
}
|
|
|
|
if( leftover )
|
|
{
|
|
/* If we are on the leftover bytes in a decrypt operation, we need to
|
|
* use the previous tweak for these bytes (as saved in prev_tweak). */
|
|
unsigned char *t = mode == MBEDTLS_AES_DECRYPT ? prev_tweak : tweak;
|
|
|
|
/* We are now on the final part of the data unit, which doesn't divide
|
|
* evenly by 16. It's time for ciphertext stealing. */
|
|
size_t i;
|
|
unsigned char *prev_output = output - 16;
|
|
|
|
/* Copy ciphertext bytes from the previous block to our output for each
|
|
* byte of cyphertext we won't steal. At the same time, copy the
|
|
* remainder of the input for this final round (since the loop bounds
|
|
* are the same). */
|
|
for( i = 0; i < leftover; i++ )
|
|
{
|
|
output[i] = prev_output[i];
|
|
tmp[i] = input[i] ^ t[i];
|
|
}
|
|
|
|
/* Copy ciphertext bytes from the previous block for input in this
|
|
* round. */
|
|
for( ; i < 16; i++ )
|
|
tmp[i] = prev_output[i] ^ t[i];
|
|
|
|
ret = esp_aes_crypt_ecb( &ctx->crypt, mode, tmp, tmp );
|
|
if( ret != 0 )
|
|
return ret;
|
|
|
|
/* Write the result back to the previous block, overriding the previous
|
|
* output we copied. */
|
|
for( i = 0; i < 16; i++ )
|
|
prev_output[i] = tmp[i] ^ t[i];
|
|
}
|
|
|
|
return( 0 );
|
|
}
|