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esp-idf/components/mbedtls/port/esp32s2/aes.c
morris e30cd361a8 global: rename esp32s2beta to esp32s2
2020-01-22 12:14:38 +08:00

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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 <stdio.h>
#include <string.h>
#include <sys/lock.h>
#include "mbedtls/aes.h"
#include "esp32s2/aes.h"
#include "esp32s2/gcm.h"
#include "soc/soc.h"
#include "soc/cpu.h"
#include "soc/dport_reg.h"
#include "soc/hwcrypto_reg.h"
#include "soc/crypto_dma_reg.h"
#include "esp32s2/crypto_dma.h"
#include "esp32s2/rom/lldesc.h"
#include "esp32s2/rom/cache.h"
#include "soc/periph_defs.h"
#include "esp_intr_alloc.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#define AES_BLOCK_BYTES 16
#define LE_TO_BE(x) (((x) >> 24) & 0x000000ff) | \
(((x) << 24) & 0xff000000) | \
(((x) >> 8) & 0x0000ff00) | \
(((x) << 8) & 0x00ff0000)
static inline uint32_t WPA_GET_BE32(const uint8_t *a)
{
return ((uint32_t) a[0] << 24) | (a[1] << 16) | (a[2] << 8) | a[3];
}
static inline void WPA_PUT_BE32(uint8_t *a, uint32_t val)
{
a[0] = (val >> 24) & 0xff;
a[1] = (val >> 16) & 0xff;
a[2] = (val >> 8) & 0xff;
a[3] = val & 0xff;
}
/* Enable this if want to use AES interrupt */
//#define CONFIG_MBEDTLS_AES_USE_INTERRUPT
portMUX_TYPE crypto_dma_spinlock = portMUX_INITIALIZER_UNLOCKED;
#if defined(CONFIG_MBEDTLS_AES_USE_INTERRUPT)
static SemaphoreHandle_t op_complete_sem;
#endif
/* AES uses a spinlock mux not a lock as the underlying block operation
only takes a small number of cycles, much less than using
a mutex for this.
For CBC, CFB, etc. this may mean that interrupts are disabled for a longer
period of time for bigger data lengths.
*/
portMUX_TYPE aes_spinlock = portMUX_INITIALIZER_UNLOCKED;
/* The function will pad 0 if the length is not multiple of
* 16 bytes for the incoming data buffer
*/
static uint8_t *textpad_zero(const unsigned char *buf, unsigned char *len)
{
uint8_t offset;
uint8_t *data = NULL;
offset = *len % AES_BLOCK_BYTES;
if (offset) {
data = (uint8_t *)calloc(1, (*len + (AES_BLOCK_BYTES - offset)));
if (data) {
memcpy(data, buf, *len);
*len += (AES_BLOCK_BYTES - offset);
}
}
return data;
}
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 )
{
/* newlib locks lazy initialize on ESP-IDF */
portENTER_CRITICAL(&aes_spinlock);
/* Need to lock DMA since it is shared with SHA block */
portENTER_CRITICAL(&crypto_dma_spinlock);
/* Enable AES hardware */
REG_SET_BIT(DPORT_PERIP_CLK_EN1_REG, DPORT_CRYPTO_AES_CLK_EN | DPORT_CRYPTO_DMA_CLK_EN);
/* Clear reset on digital signature unit,
otherwise AES unit is held in reset also. */
REG_CLR_BIT(DPORT_PERIP_RST_EN1_REG,
DPORT_CRYPTO_AES_RST | DPORT_CRYPTO_DMA_RST | DPORT_CRYPTO_DS_RST);
}
/* Function to disable AES and Crypto DMA clocks and release locks */
void esp_aes_release_hardware( void )
{
/* Disable DMA mode */
REG_WRITE(AES_DMA_ENABLE_REG, 0);
/* Disable AES hardware */
REG_SET_BIT(DPORT_PERIP_RST_EN1_REG, DPORT_CRYPTO_AES_RST | DPORT_CRYPTO_DMA_RST);
/* Don't return other units to reset, as this pulls
reset on RSA & SHA units, respectively. */
REG_CLR_BIT(DPORT_PERIP_CLK_EN1_REG, DPORT_CRYPTO_AES_CLK_EN | DPORT_CRYPTO_DMA_CLK_EN);
portEXIT_CRITICAL(&crypto_dma_spinlock);
portEXIT_CRITICAL(&aes_spinlock);
}
/* Function to init AES context to zero */
void esp_aes_init( esp_aes_context *ctx )
{
if ( ctx == NULL ) {
return;
}
bzero( ctx, sizeof( esp_aes_context ) );
}
/* Function to clear 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. Also, set the AES block mode
* (ECb, CBC, CFB, OFB, GCM, CTR) and crypt mode (ENCRYPT/DECRYPT)
* Enable the DMA mode of operation
*
* Call only while holding esp_aes_acquire_hardware().
*/
static inline void esp_aes_setkey_hardware( esp_aes_context *ctx, int crypt_mode, uint8_t block_mode)
{
const uint32_t MODE_DECRYPT_BIT = 4;
unsigned mode_reg_base = (crypt_mode == ESP_AES_ENCRYPT) ? 0 : MODE_DECRYPT_BIT;
ctx->key_in_hardware = 0;
for (int i = 0; i < ctx->key_bytes/4; ++i) {
REG_WRITE(AES_KEY_BASE + i * 4, *(((uint32_t *)ctx->key) + i));
ctx->key_in_hardware += 4;
}
REG_WRITE(AES_MODE_REG, mode_reg_base + ((ctx->key_bytes / 8) - 2));
/* Set the algorithm mode CBC, CFB ... */
REG_WRITE(AES_BLOCK_MODE_REG, block_mode);
/* Set the ENDIAN reg */
REG_WRITE(AES_ENDIAN_REG, 0x3F);
/* Enable DMA mode */
REG_WRITE(AES_DMA_ENABLE_REG, 1);
/* Presently hard-coding the INC function to 32 bit */
if (block_mode == AES_BLOCK_MODE_CTR) {
REG_WRITE(AES_INC_SEL_REG, 0);
}
/* 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();
}
}
/*
* Function to write IV to hardware iv registers
*/
static inline void esp_aes_set_iv(uint8_t *iv, uint8_t len)
{
memcpy((uint8_t *)AES_IV_BASE, iv, len);
}
/*
* Function to read IV from hardware iv registers
*/
static inline void esp_aes_get_iv(uint8_t *iv, uint8_t len)
{
memcpy(iv, (uint8_t *)AES_IV_BASE, len);
}
/* Function to set block number & trigger bit for AES GCM operation
*/
static inline void esp_aes_gcm_set_block_num_and_trigger(uint16_t len)
{
/* Write the number of blocks */
REG_WRITE(AES_BLOCK_NUM_REG, (len / AES_BLOCK_BYTES));
REG_WRITE(AES_TRIGGER_REG, 1);
while (REG_READ(AES_STATE_REG) != AES_STATE_IDLE) {
}
}
/* For AES-GCM mode once H has been calculated
* continue the AES operation & wait for DMA
* to finish if input data length is non-zero
* */
static inline void esp_aes_gcm_continue(size_t len)
{
volatile uint32_t dma_done = 0;
REG_WRITE(AES_CONTINUE_REG, 1);
while (REG_READ(AES_STATE_REG) != AES_STATE_DONE) {
}
if (len == 0) {
REG_WRITE(AES_DMA_EXIT_REG, 1);
return;
}
/* Wait for AES-GCM DMA operation to complete */
while (1) {
dma_done = REG_READ(CRYPTO_DMA_INT_RAW_REG);
if ((dma_done & INT_RAW_IN_SUC_EOF) == INT_RAW_IN_SUC_EOF) {
break;
}
}
REG_WRITE(AES_DMA_EXIT_REG, 1);
}
#if defined (CONFIG_MBEDTLS_AES_USE_INTERRUPT)
static IRAM_ATTR void esp_aes_dma_isr(void *arg)
{
BaseType_t higher_woken;
REG_WRITE(AES_INT_CLR_REG, 1);
xSemaphoreGiveFromISR(op_complete_sem, &higher_woken);
if (higher_woken) {
portYIELD_FROM_ISR();
}
}
#endif
/* Wait for AES hardware block operation to complete */
static int esp_aes_dma_complete(void)
{
#if defined (CONFIG_MBEDTLS_AES_USE_INTERRUPT)
if (!xSemaphoreTake(op_complete_sem, 2000 / portTICK_PERIOD_MS)) {
ESP_LOGE("AES", "Timed out waiting for completion of AES Interrupt");
abort();
}
#endif
/* Checking this if interrupt is used also, to avoid
issues with AES fault injection
*/
while (REG_READ(AES_STATE_REG) != AES_STATE_DONE) {
}
return 0;
}
/* Perform AES-DMA operation and wait until the DMA operation is over
*
* input = Input data buffer, length len
* output = Output data buffer, length len
* len = Length of data in bytes, may not be multiple of AES block size
* stream_out = Pointer to 16 byte buffer to hold final stream block, if
* len is not a multiple of AES block size (16)
*
* The DMA processing works in following way:
*
* - If len >= AES_BLOCK_BYTES, there are DMA input and output
* descriptors which point to input & output (in_block_desc, out_block_desc) directly,
* to process block_bytes bytes.
*
* - If len % AES_BLOCK_BYTES != 0 then unaligned bytes are copied to stream_in block which is
* padded with zeroes. DMA descriptors (stream_in_desc, stream_out_desc) process this block and output to
* stream_out buffer argument. Otherwise, stream_out argument is ignored (may be NULL).
*
* - If both above conditions are true, DMA has two linked list input buffers and two linked list output buffers,
* and processes first the blocks and then the partial stream block.
*
* After the DMA operation, if we only processed full bytes then the IV memory block will contain the next IV
* for the configured AES mode.
*
* If a partial "stream block" was processed then IV memory block will contain a garbage IV value, because of
* the partial stream block. The IV can be recovered from the stream_out block (depending on algorithm some
* post-processing of the 'output' bytes also in stream_out may be needed, to translate them back to correct IV bytes).
*
*/
static int esp_aes_process_dma(esp_aes_context *ctx, const unsigned char *input, unsigned char *output, uint16_t len, uint8_t *stream_out)
{
volatile lldesc_t block_in_desc, block_out_desc, stream_in_desc, stream_out_desc;
volatile lldesc_t *in_desc_head, *out_desc_head;
volatile uint32_t dma_done = 0;
uint8_t stream_in[16];
unsigned stream_bytes = len % AES_BLOCK_BYTES; // bytes which aren't in a full block
unsigned block_bytes = len - stream_bytes; // bytes which are in a full block
unsigned blocks = (block_bytes / AES_BLOCK_BYTES) + ((stream_bytes > 0) ? 1 : 0);
assert(len > 0); // caller shouldn't ever have len set to zero
assert(stream_bytes == 0 || stream_out != NULL); // stream_out can be NULL if we're processing full block(s)
/* 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;
}
if (block_bytes > 0) {
/* If the block length is less than 16 we use internal RAM so no
* need to flush Cache
*/
#if (CONFIG_SPIRAM_USE_CAPS_ALLOC || CONFIG_SPIRAM_USE_MALLOC)
if ((unsigned int)input >= SOC_EXTRAM_DATA_LOW && (unsigned int)input <= SOC_EXTRAM_DATA_HIGH) {
assert((((unsigned int)(input) & 0xF) == 0));
Cache_WriteBack_All();
}
if ((unsigned int)output >= SOC_EXTRAM_DATA_LOW && (unsigned int)output <= SOC_EXTRAM_DATA_HIGH) {
assert((((unsigned int)(output) & 0xF) == 0));
}
#endif
block_in_desc = (lldesc_t) {
.length = block_bytes,
.size = block_bytes,
.buf = (void *)input,
.owner = 1,
.empty = (stream_bytes > 0) ? (uint32_t)&stream_in_desc : 0,
.eof = (stream_bytes == 0),
};
block_out_desc = (lldesc_t) {
.length = block_bytes,
.size = block_bytes,
.buf = output,
.owner = 1,
.empty = (stream_bytes > 0) ? (uint32_t)&stream_out_desc : 0,
.eof = (stream_bytes == 0),
};
in_desc_head = &block_in_desc;
out_desc_head = &block_out_desc;
}
if (stream_bytes > 0) {
// can't read past end of 'input', so make a zero padded input buffer in RAM
memcpy(stream_in, input + block_bytes, stream_bytes);
bzero(stream_in + stream_bytes, AES_BLOCK_BYTES - stream_bytes);
stream_in_desc = (lldesc_t) {
.length = AES_BLOCK_BYTES,
.size = AES_BLOCK_BYTES,
.buf = stream_in,
.owner = 1,
.eof = 1,
};
stream_out_desc = (lldesc_t) {
.length = AES_BLOCK_BYTES,
.size = AES_BLOCK_BYTES,
.buf = stream_out,
.owner = 1,
.eof = 1,
};
}
// block buffers are sent to DMA first, unless there aren't any
in_desc_head = (block_bytes > 0) ? &block_in_desc : &stream_in_desc;
out_desc_head = (block_bytes > 0) ? &block_out_desc : &stream_out_desc;
/* Enable the DMA clock - currently only for FPGA test */
#if CONFIG_IDF_ENV_FPGA
SET_PERI_REG_MASK(CRYPTO_DMA_CONF0_REG, CONF0_REG_GEN_CLK_EN);
#endif
/* Reset DMA */
SET_PERI_REG_MASK(CRYPTO_DMA_CONF0_REG, CONF0_REG_AHBM_RST | CONF0_REG_IN_RST | CONF0_REG_OUT_RST | CONF0_REG_AHBM_FIFO_RST);
CLEAR_PERI_REG_MASK(CRYPTO_DMA_CONF0_REG, CONF0_REG_AHBM_RST | CONF0_REG_IN_RST | CONF0_REG_OUT_RST | CONF0_REG_AHBM_FIFO_RST);
/* Set DMA for AES Use */
REG_WRITE(CRYPTO_DMA_AES_SHA_SELECT_REG, 0);
/* Set descriptors */
CLEAR_PERI_REG_MASK(CRYPTO_DMA_OUT_LINK_REG, OUT_LINK_REG_OUTLINK_ADDR);
SET_PERI_REG_MASK(CRYPTO_DMA_OUT_LINK_REG, ((uint32_t)(in_desc_head))&OUT_LINK_REG_OUTLINK_ADDR);
CLEAR_PERI_REG_MASK(CRYPTO_DMA_IN_LINK_REG, IN_LINK_REG_INLINK_ADDR);
SET_PERI_REG_MASK(CRYPTO_DMA_IN_LINK_REG, ((uint32_t)(out_desc_head))&IN_LINK_REG_INLINK_ADDR);
/* Start transfer */
SET_PERI_REG_MASK(CRYPTO_DMA_OUT_LINK_REG, OUT_LINK_REG_OUTLINK_START);
SET_PERI_REG_MASK(CRYPTO_DMA_IN_LINK_REG, IN_LINK_REG_INLINK_START);
/* Write the number of blocks */
REG_WRITE(AES_BLOCK_NUM_REG, blocks);
#if defined (CONFIG_MBEDTLS_AES_USE_INTERRUPT)
REG_WRITE(AES_INT_CLR_REG, 1);
if (op_complete_sem == NULL) {
op_complete_sem = xSemaphoreCreateBinary();
esp_intr_alloc(ETS_AES_INTR_SOURCE, 0, esp_aes_dma_isr, 0, 0);
}
REG_WRITE(AES_INT_ENA_REG, 1);
#endif
/* Start AES operation */
REG_WRITE(AES_TRIGGER_REG, 1);
esp_aes_dma_complete();
/* Wait for DMA operation to complete */
while (1) {
dma_done = REG_READ(CRYPTO_DMA_INT_RAW_REG);
if ( (dma_done & INT_RAW_IN_SUC_EOF) == INT_RAW_IN_SUC_EOF) {
break;
}
}
REG_WRITE(AES_DMA_EXIT_REG, 1);
#if (CONFIG_SPIRAM_USE_CAPS_ALLOC || CONFIG_SPIRAM_USE_MALLOC)
if (block_bytes > 0) {
if ((unsigned int)input >= SOC_EXTRAM_DATA_LOW && (unsigned int)input <= SOC_EXTRAM_DATA_HIGH) {
Cache_Invalidate_DCache_All();
}
}
#endif
if (stream_bytes > 0) {
memcpy(output + block_bytes, stream_out, stream_bytes);
}
return 0;
}
/*
* AES-ECB single 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();
esp_aes_setkey_hardware(ctx, ESP_AES_ENCRYPT, AES_BLOCK_MODE_ECB);
r = esp_aes_process_dma(ctx, input, output, AES_BLOCK_BYTES, NULL);
esp_aes_release_hardware();
return r;
}
void esp_aes_encrypt( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
esp_internal_aes_encrypt(ctx, input, output);
}
/*
* AES-ECB single 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();
esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT, AES_BLOCK_MODE_ECB);
r = esp_aes_process_dma(ctx, input, output, AES_BLOCK_BYTES, NULL);
esp_aes_release_hardware();
return r;
}
void esp_aes_decrypt( esp_aes_context *ctx,
const unsigned char input[16],
unsigned char output[16] )
{
esp_internal_aes_decrypt(ctx, input, output);
}
/*
* 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, AES_BLOCK_MODE_ECB);
r = esp_aes_process_dma(ctx, input, output, AES_BLOCK_BYTES, NULL);
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 )
{
/* For CBC input length should be multiple of
* AES BLOCK BYTES
* */
if ( length % AES_BLOCK_BYTES ) {
return ERR_ESP_AES_INVALID_INPUT_LENGTH;
}
if ( length == 0 ) {
return 0;
}
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, AES_BLOCK_MODE_CBC);
esp_aes_set_iv(iv, AES_BLOCK_BYTES);
esp_aes_process_dma(ctx, input, output, length, NULL);
esp_aes_get_iv(iv, AES_BLOCK_BYTES);
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];
size_t block_bytes = length - (length % AES_BLOCK_BYTES);
/* The DMA engine will only output correct IV if it runs
full blocks of input in CFB8 mode
*/
if (block_bytes > 0) {
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, mode, AES_BLOCK_MODE_CFB8);
esp_aes_set_iv(iv, AES_BLOCK_BYTES);
esp_aes_process_dma(ctx, input, output, block_bytes, NULL);
esp_aes_get_iv(iv, AES_BLOCK_BYTES);
esp_aes_release_hardware();
length -= block_bytes;
input += block_bytes;
output += block_bytes;
}
// Process remaining bytes block-at-a-time in ECB mode
if (length > 0) {
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, MBEDTLS_AES_ENCRYPT, AES_BLOCK_MODE_ECB);
while ( length-- ) {
memcpy( ov, iv, 16 );
esp_aes_process_dma(ctx, iv, iv, AES_BLOCK_BYTES, NULL);
if ( mode == MBEDTLS_AES_DECRYPT ) {
ov[16] = *input;
}
c = *output++ = ( iv[0] ^ *input++ );
if ( mode == MBEDTLS_AES_ENCRYPT ) {
ov[16] = c;
}
memcpy( iv, ov + 1, 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 )
{
uint8_t c;
size_t stream_bytes = 0;
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;
/* Lets process the *iv_off bytes first
* which are pending from the previous call to this API
*/
while (n > 0 && length > 0) {
if (mode == MBEDTLS_AES_ENCRYPT) {
iv[n] = *output++ = (unsigned char)(*input++ ^ iv[n]);
} else {
c = *input++;
*output++ = (c ^ iv[n]);
iv[n] = c;
}
n = (n + 1) % AES_BLOCK_BYTES;
length--;
}
if (length > 0) {
stream_bytes = length % AES_BLOCK_BYTES;
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, mode, AES_BLOCK_MODE_CFB128);
esp_aes_set_iv(iv, AES_BLOCK_BYTES);
esp_aes_process_dma(ctx, input, output, length, iv);
if (stream_bytes == 0) {
// if we didn't need the partial 'stream block' then the new IV is in the IV register
esp_aes_get_iv(iv, AES_BLOCK_BYTES);
} else {
// if we did process a final partial block the new IV is already processed via DMA (and has some bytes of output in it),
// In decrypt mode any partial bytes are output plaintext (iv ^ c) and need to be swapped back to ciphertext (as the next
// block uses ciphertext as its IV input)
//
// Note: It may be more efficient to not process the partial block via DMA in this case.
if (mode == MBEDTLS_AES_DECRYPT) {
memcpy(iv, input + length - stream_bytes, stream_bytes);
}
}
esp_aes_release_hardware();
}
*iv_off = n + stream_bytes;
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 )
{
size_t n = *nc_off;
while (n > 0 && length > 0) {
*output++ = (unsigned char)(*input++ ^ stream_block[n]);
n = (n + 1) & 0xF;
length--;
}
if (length > 0) {
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT, AES_BLOCK_MODE_CTR);
esp_aes_set_iv(nonce_counter, AES_BLOCK_BYTES);
esp_aes_process_dma(ctx, input, output, length, stream_block);
esp_aes_get_iv(nonce_counter, AES_BLOCK_BYTES);
esp_aes_release_hardware();
}
*nc_off = n + (length % AES_BLOCK_BYTES);
return 0;
}
/* XOR two 32 bit words */
static void xor_block(uint8_t *dst, const uint8_t *src)
{
uint32_t *d = (uint32_t *) dst;
uint32_t *s = (uint32_t *) src;
*d++ ^= *s++;
*d++ ^= *s++;
*d++ ^= *s++;
*d++ ^= *s++;
}
static void right_shift(uint8_t *v)
{
uint32_t val;
val = WPA_GET_BE32(v + 12);
val >>= 1;
if (v[11] & 0x01) {
val |= 0x80000000;
}
WPA_PUT_BE32(v + 12, val);
val = WPA_GET_BE32(v + 8);
val >>= 1;
if (v[7] & 0x01) {
val |= 0x80000000;
}
WPA_PUT_BE32(v + 8, val);
val = WPA_GET_BE32(v + 4);
val >>= 1;
if (v[3] & 0x01) {
val |= 0x80000000;
}
WPA_PUT_BE32(v + 4, val);
val = WPA_GET_BE32(v);
val >>= 1;
WPA_PUT_BE32(v, val);
}
/* AES-GCM multiplication z = y * h */
static int gcm_mult(uint8_t *y, uint8_t *h, uint8_t *z)
{
uint8_t v0[AES_BLOCK_BYTES];
int i, j;
if (!y || !h || !z) {
return -1;
}
memset(z, 0, AES_BLOCK_BYTES);
memcpy(v0, y, AES_BLOCK_BYTES);
for (i = 0; i < AES_BLOCK_BYTES; i++) {
for (j = 0; j < 8; j++) {
if (y[i] & BIT(7 - j)) {
xor_block(z, v0);
}
if (v0[15] & 0x01) {
right_shift(v0);
v0[0] ^= 0xE1;
} else {
right_shift(v0);
}
}
}
return 0;
}
/* Update the key value in gcm context */
int esp_aes_gcm_setkey( esp_aes_gcm_context *ctx,
mbedtls_cipher_id_t cipher,
const unsigned char *key,
unsigned int keybits )
{
if (keybits != 128 && keybits != 192 && keybits != 256) {
return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH;
}
ctx->aes_ctx.key_bytes = keybits / 8;
memcpy(ctx->aes_ctx.key, key, ctx->aes_ctx.key_bytes);
return ( 0 );
}
/* AES-GCM GHASH calculation for IV != 12 bytes */
static void esp_aes_gcm_ghash(uint8_t *h0, uint8_t *iv, uint8_t iv_len, uint8_t *j0, uint16_t s)
{
uint8_t *hash_buf;
uint8_t y0[AES_BLOCK_BYTES], old_y0[AES_BLOCK_BYTES];
uint16_t len, rem = 0;
memset(old_y0, 0, AES_BLOCK_BYTES);
/* We need to concatenate IV, s + 8 byte zeros & 8 byte IV length
* J0 = GHASH( IV || 0 ^(s+64) || len(IV)^64 )
*/
len = ( iv_len + (s + 8) + 8 );
hash_buf = calloc( 1, len );
if (hash_buf) {
memcpy(hash_buf, iv, iv_len);
// ToDo: iv_len is 1 byte in size, how to copy 8 bytes to other memory?
#if 0
memcpy((hash_buf + iv_len + s + 8), &iv_len, 8);
#endif
/* GHASH(x) calculation
* Let X1, X2, ... , Xm-1, Xm denote the unique sequence of blocks
* such that X = X1 || X2 || ... || Xm-1 || Xm.
* Let Y0 be the “zero block,” 0 ^ 128.
* Fori=1,...,m, let Yi =(Yi-1 xor Xi) • H.
* Return Ym
*/
while (len) {
rem = ( len > AES_BLOCK_BYTES ) ? AES_BLOCK_BYTES : len;
/* Yi-1 xor hash_buf */
for (uint8_t j = 0; j < rem; j++) {
y0[j] = old_y0[j] ^ hash_buf[j];
}
/* gcm multiplication : y0 x h0 */
gcm_mult(y0, h0, j0);
memcpy(old_y0, y0, rem);
hash_buf += rem;
len -= rem;
}
memcpy(j0, y0, rem);
free(hash_buf);
}
}
/* AES-GCM J0 calculation
*/
static void inline esp_aes_gcm_process_J0(uint8_t *data, uint8_t iv_len)
{
uint8_t j_buf[AES_BLOCK_BYTES];
uint8_t iv[32];
uint16_t s;
esp_aes_get_iv(iv, iv_len);
/* If IV is 96 bits J0 = ( IV || 0^31 || 1 ) */
if (iv_len == 12) {
memset(j_buf, 0, AES_BLOCK_BYTES);
memcpy(j_buf, iv, iv_len);
j_buf[AES_BLOCK_BYTES - 1] |= 1;
} else {
/* If IV is != 96 bits then
* J0 = GHASH( IV || 0 ^(s+64) || len(IV)^64 ) where
* s = ( 128 * floor of ( len(IV) / 128 ) - len(IV) )
* floor of (x) denotes to be the least integer no less than x
* for example: floor of (1.5) = 2 since 2 is the least integer
* which is no less than 1.5
*/
s = ((iv_len / AES_BLOCK_BYTES) +
((iv_len % AES_BLOCK_BYTES) == 0) ? 0 : 1);
s = (s * AES_BLOCK_BYTES) - iv_len;
esp_aes_gcm_ghash(data, iv, iv_len, j_buf, s);
}
/* Write J0 to hardware registers */
memcpy((uint8_t *)AES_J_BASE, j_buf, AES_BLOCK_BYTES);
}
/* Configure & start crypto DMA for AES GCM operation
*/
static void esp_aes_gcm_dma(unsigned char *aad, esp_aes_gcm_context *ctx,
unsigned char *input, size_t ilen,
unsigned char *len_buf, unsigned char *output)
{
volatile lldesc_t dma_descr[4];
int i = 0;
bzero( (void *)dma_descr, sizeof( dma_descr ) );
#if (CONFIG_SPIRAM_USE_CAPS_ALLOC || CONFIG_SPIRAM_USE_MALLOC)
if ((unsigned int)input >= SOC_EXTRAM_DATA_LOW && (unsigned int)input <= SOC_EXTRAM_DATA_HIGH) {
assert((((unsigned int)(input) & 0xF) == 0));
Cache_WriteBack_All();
}
if ((unsigned int)output >= SOC_EXTRAM_DATA_LOW && (unsigned int)output <= SOC_EXTRAM_DATA_HIGH) {
assert((((unsigned int)(output) & 0xF) == 0));
}
#endif
dma_descr[0].length = ctx->aad_len;
dma_descr[0].size = ctx->aad_len;
dma_descr[0].buf = aad;
dma_descr[0].owner = 1;
dma_descr[0].eof = 0;
dma_descr[0].empty = (uint32_t)&dma_descr[1];
dma_descr[1].length = ilen;
dma_descr[1].size = ilen;
dma_descr[1].buf = input;
dma_descr[1].owner = 1;
dma_descr[1].eof = 0;
dma_descr[1].empty = (uint32_t)&dma_descr[2];
dma_descr[2].length = AES_BLOCK_BYTES;
dma_descr[2].size = AES_BLOCK_BYTES;
dma_descr[2].buf = len_buf;
dma_descr[2].owner = 1;
dma_descr[2].eof = 1;
dma_descr[2].empty = 0;
dma_descr[3].length = ctx->aad_len + ilen + AES_BLOCK_BYTES;
dma_descr[3].size = ctx->aad_len + ilen + AES_BLOCK_BYTES;
dma_descr[3].buf = output;
dma_descr[3].owner = 1;
dma_descr[3].eof = 1;
dma_descr[3].empty = 0;
/* If no additional authentication data */
if (ctx->aad_len == 0) {
i = 1;
}
/* If no input data */
if (ilen == 0) {
i = 2;
}
/* Enable the DMA clock - currently only for FPGA test */
#if CONFIG_IDF_ENV_FPGA
SET_PERI_REG_MASK(CRYPTO_DMA_CONF0_REG, CONF0_REG_GEN_CLK_EN);
#endif
/* Reset DMA */
SET_PERI_REG_MASK(CRYPTO_DMA_CONF0_REG, CONF0_REG_AHBM_RST | CONF0_REG_IN_RST | CONF0_REG_OUT_RST | CONF0_REG_AHBM_FIFO_RST);
CLEAR_PERI_REG_MASK(CRYPTO_DMA_CONF0_REG, CONF0_REG_AHBM_RST | CONF0_REG_IN_RST | CONF0_REG_OUT_RST | CONF0_REG_AHBM_FIFO_RST);
/* Set DMA for AES Use */
REG_WRITE(CRYPTO_DMA_AES_SHA_SELECT_REG, 0);
/* Set descriptors */
CLEAR_PERI_REG_MASK(CRYPTO_DMA_OUT_LINK_REG, OUT_LINK_REG_OUTLINK_ADDR);
SET_PERI_REG_MASK(CRYPTO_DMA_OUT_LINK_REG, ((uint32_t)(&dma_descr[i]))&OUT_LINK_REG_OUTLINK_ADDR);
CLEAR_PERI_REG_MASK(CRYPTO_DMA_IN_LINK_REG, IN_LINK_REG_INLINK_ADDR);
SET_PERI_REG_MASK(CRYPTO_DMA_IN_LINK_REG, ((uint32_t)(&dma_descr[3]))&IN_LINK_REG_INLINK_ADDR);
/* Start transfer */
SET_PERI_REG_MASK(CRYPTO_DMA_OUT_LINK_REG, OUT_LINK_REG_OUTLINK_START);
SET_PERI_REG_MASK(CRYPTO_DMA_IN_LINK_REG, IN_LINK_REG_INLINK_START);
/* Trigger AES: Let hardware perform GCTR operation */
esp_aes_gcm_set_block_num_and_trigger(ilen);
/* While hardware is busy meanwhile software will calculate GHASH
* Read H from hardware register
*/
memcpy(ctx->H, (uint8_t *)AES_H_BASE, AES_BLOCK_BYTES);
esp_aes_gcm_process_J0(ctx->H, ctx->iv_len);
/* After following call the ciphertext is available in output buffer */
esp_aes_gcm_continue(ilen);
#if (CONFIG_SPIRAM_USE_CAPS_ALLOC || CONFIG_SPIRAM_USE_MALLOC)
if ((unsigned int)input >= SOC_EXTRAM_DATA_LOW && (unsigned int)input <= SOC_EXTRAM_DATA_HIGH) {
Cache_Invalidate_DCache_All();
}
#endif
}
/* Function to init AES GCM context to zero */
void esp_aes_gcm_init( esp_aes_gcm_context *ctx)
{
if (ctx == NULL) {
return;
}
bzero(ctx, sizeof(esp_aes_gcm_context));
}
/* Function to clear AES-GCM context */
void esp_aes_gcm_free( esp_aes_gcm_context *ctx)
{
if (ctx == NULL) {
return;
}
bzero(ctx, sizeof(esp_aes_gcm_context));
}
/* Setup AES-GCM */
int esp_aes_gcm_starts( esp_aes_gcm_context *ctx,
int mode,
const unsigned char *iv,
size_t iv_len,
const unsigned char *aad,
size_t aad_len )
{
uint8_t temp[AES_BLOCK_BYTES] = {0};
memcpy(temp, iv, iv_len);
esp_aes_acquire_hardware();
esp_aes_setkey_hardware( &ctx->aes_ctx, mode, AES_BLOCK_MODE_GCM);
/* AES-GCM HW does not use IV but we program anyways so that
* we can retrieve later for J0 calculation */
esp_aes_set_iv(temp, iv_len);
ctx->iv_len = iv_len;
ctx->aad = aad;
ctx->aad_len = aad_len;
return ( 0 );
}
/* Perform AES-GCM operation */
int esp_aes_gcm_update( esp_aes_gcm_context *ctx,
size_t length,
const unsigned char *input,
unsigned char *output )
{
const uint8_t *dbuf = input;
uint8_t *abuf = (uint8_t *)ctx->aad;
uint64_t ori_aad_len = ctx->aad_len, ori_p_len = length;
uint32_t temp[4] = {0};
bool abuf_alloc = false, dbuf_alloc = false;
if ( output > input && (size_t) ( output - input ) < length ) {
return ( MBEDTLS_ERR_GCM_BAD_INPUT );
}
/* Check length of AAD & pad if required */
if (ctx->aad_len % AES_BLOCK_BYTES) {
ori_aad_len = ctx->aad_len;
abuf = textpad_zero(ctx->aad, (uint8_t *)&ctx->aad_len);
if (!abuf) {
return -1;
} else {
abuf_alloc = true;
}
}
/* Check length of input & pad if required */
if ( length % AES_BLOCK_BYTES ) {
ori_p_len = length;
REG_WRITE(AES_BIT_VALID_NUM_REG, (length % AES_BLOCK_BYTES) * 8);
dbuf = textpad_zero(input, (uint8_t *)&length);
if (!dbuf) {
if (abuf_alloc) {
free(abuf);
return -1;
}
} else {
dbuf_alloc = true;
}
}
/* Update number of AAD blocks in hardware register */
REG_WRITE(AES_AAD_BLOCK_NUM_REG, (ctx->aad_len / AES_BLOCK_BYTES));
/* Input buffer is: length[textpad(input)] + length[textpad(aad)]
* + [length]64 + [aad_len]64
*/
ori_aad_len *= 8;
ori_p_len *= 8;
temp[0] = (uint32_t)LE_TO_BE(ori_aad_len >> 32);
temp[1] = (uint32_t)LE_TO_BE(ori_aad_len);
temp[2] = (uint32_t)LE_TO_BE(ori_p_len >> 32);
temp[3] = (uint32_t)LE_TO_BE(ori_p_len);
esp_aes_gcm_dma(abuf, ctx, (uint8_t *)dbuf, length, (uint8_t *)temp, output);
if (abuf_alloc) {
free((void *)abuf);
}
if (dbuf_alloc) {
free((void *)dbuf);
}
return 0;
}
/* Function to read the tag value */
int esp_aes_gcm_finish( esp_aes_gcm_context *ctx,
unsigned char *tag,
size_t tag_len )
{
memcpy(tag, (uint8_t *)AES_T_BASE, tag_len);
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 )
{
size_t n = *iv_off;
size_t stream_bytes = 0;
while (n > 0 && length > 0) {
*output++ = (unsigned char)(*input++ ^ iv[n]);
n = (n + 1) & 0xF;
length--;
}
if (length > 0) {
stream_bytes = (length % AES_BLOCK_BYTES);
esp_aes_acquire_hardware();
esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT, AES_BLOCK_MODE_OFB);
esp_aes_set_iv(iv, AES_BLOCK_BYTES);
esp_aes_process_dma(ctx, input, output, length, iv);
if (stream_bytes == 0) {
// new IV is in the IV block
esp_aes_get_iv(iv, AES_BLOCK_BYTES);
} else {
// IV is in the iv buffer (stream_out param), however 'stream_bytes'
// of it are already XORed with input bytes so need to un-XOR them
for (int i = 0; i < stream_bytes; i++) {
iv[i] ^= input[length - stream_bytes + i];
}
}
esp_aes_release_hardware();
}
*iv_off = n + stream_bytes;
return 0;
}
/* Below XTS implementation is copied aes.c of mbedtls library.
* When MBEDTLS_AES_ALT is defined mbedtls expects alternate
* definition of XTS functions to be available. Even if this
* could have been avoided, it is done for consistency reason.
*/
void esp_aes_xts_init( esp_aes_xts_context *ctx )
{
esp_aes_init( &ctx->crypt );
esp_aes_init( &ctx->tweak );
}
void esp_aes_xts_free( esp_aes_xts_context *ctx )
{
esp_aes_free( &ctx->crypt );
esp_aes_free( &ctx->tweak );
}
static int esp_aes_xts_decode_keys( const unsigned char *key,
unsigned int keybits,
const unsigned char **key1,
unsigned int *key1bits,
const unsigned char **key2,
unsigned int *key2bits )
{
const unsigned int half_keybits = keybits / 2;
const unsigned int half_keybytes = half_keybits / 8;
switch( keybits )
{
case 256: break;
case 512: break;
default : return( MBEDTLS_ERR_AES_INVALID_KEY_LENGTH );
}
*key1bits = half_keybits;
*key2bits = half_keybits;
*key1 = &key[0];
*key2 = &key[half_keybytes];
return 0;
}
int esp_aes_xts_setkey_enc( esp_aes_xts_context *ctx,
const unsigned char *key,
unsigned int keybits)
{
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 the encryption mode. */
ret = esp_aes_setkey( &ctx->tweak, key2, key2bits );
if( ret != 0 )
return( ret );
/* Set crypt key for encryption. */
return esp_aes_setkey( &ctx->crypt, key1, key1bits );
}
int esp_aes_xts_setkey_dec( esp_aes_xts_context *ctx,
const unsigned char *key,
unsigned int keybits)
{
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 );
}
int esp_aes_gcm_crypt_and_tag( esp_aes_gcm_context *ctx,
int mode,
size_t length,
const unsigned char *iv,
size_t iv_len,
const unsigned char *add,
size_t add_len,
const unsigned char *input,
unsigned char *output,
size_t tag_len,
unsigned char *tag )
{
int ret;
if ( ( ret = esp_aes_gcm_starts( ctx, mode, iv, iv_len, add, add_len ) ) != 0 ) {
return ( ret );
}
if ( ( ret = esp_aes_gcm_update( ctx, length, input, output ) ) != 0 ) {
return ( ret );
}
if ( ( ret = esp_aes_gcm_finish( ctx, tag, tag_len ) ) != 0 ) {
return ( ret );
}
return ( 0 );
}
int esp_aes_gcm_auth_decrypt( esp_aes_gcm_context *ctx,
size_t length,
const unsigned char *iv,
size_t iv_len,
const unsigned char *add,
size_t add_len,
const unsigned char *tag,
size_t tag_len,
const unsigned char *input,
unsigned char *output )
{
int ret;
unsigned char check_tag[16];
size_t i;
int diff;
if ( ( ret = esp_aes_gcm_crypt_and_tag( ctx, ESP_AES_DECRYPT, length,
iv, iv_len, add, add_len,
input, output, tag_len, check_tag ) ) != 0 ) {
return ( ret );
}
/* Check tag in "constant-time" */
for ( diff = 0, i = 0; i < tag_len; i++ ) {
diff |= tag[i] ^ check_tag[i];
}
if ( diff != 0 ) {
bzero( output, length );
return ( MBEDTLS_ERR_GCM_AUTH_FAILED );
}
return ( 0 );
}
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