/** * \brief AES block cipher, ESP32-S2 hardware accelerated version * Based on mbedTLS FIPS-197 compliant version. * * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved * Additions Copyright (C) 2016-2020, 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 #include #include #include "mbedtls/aes.h" #include "esp32s2/aes.h" #include "esp32s2/gcm.h" #include "soc/cpu.h" #include "soc/dport_reg.h" #include "soc/hwcrypto_reg.h" #include "soc/crypto_dma_reg.h" #include "soc/periph_defs.h" #include "esp32s2/rom/lldesc.h" #include "esp32s2/rom/cache.h" #include "esp_intr_alloc.h" #include "driver/periph_ctrl.h" #include "esp_log.h" #include "soc/lldesc.h" #include "esp_heap_caps.h" #include "sys/param.h" #include "esp_pm.h" #include "esp_crypto_lock.h" #include "freertos/FreeRTOS.h" #include "freertos/semphr.h" #define AES_BLOCK_BYTES 16 #define IV_WORDS 4 /* Max size of each chunk to process when output buffer is in unaligned external ram must be a multiple of block size */ #define AES_MAX_CHUNK_WRITE_SIZE 1600 /* Input over this length will yield and wait for interrupt instead of busy-waiting, 30000 bytes is approx 0.5 ms */ #define AES_DMA_INTR_TRIG_LEN 2000 #define ESP_PUT_BE64(a, val) \ do { \ *(uint64_t*)(a) = __builtin_bswap64( (uint64_t)(val) ); \ } while (0) /* DMA AES working modes*/ typedef enum { ESP_AES_BLOCK_MODE_ECB = 0, ESP_AES_BLOCK_MODE_CBC, ESP_AES_BLOCK_MODE_OFB, ESP_AES_BLOCK_MODE_CTR, ESP_AES_BLOCK_MODE_CFB8, ESP_AES_BLOCK_MODE_CFB128, ESP_AES_BLOCK_MODE_GCM, } esp_aes_mode_t; #if defined(CONFIG_MBEDTLS_AES_USE_INTERRUPT) static SemaphoreHandle_t op_complete_sem; #if defined(CONFIG_PM_ENABLE) static esp_pm_lock_handle_t s_pm_cpu_lock; static esp_pm_lock_handle_t s_pm_sleep_lock; #endif #endif static const char *TAG = "esp-aes"; 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 ) { /* Need to lock DMA since it is shared with SHA block */ esp_crypto_dma_lock_acquire(); /* Enable AES hardware */ periph_module_enable(PERIPH_AES_DMA_MODULE); } /* Function to disable AES and Crypto DMA clocks and release locks */ void esp_aes_release_hardware( void ) { /* Disable AES hardware */ periph_module_disable(PERIPH_AES_DMA_MODULE); esp_crypto_dma_lock_release(); } /* 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. * * Call only while holding esp_aes_acquire_hardware(). */ static void esp_aes_setkey_hardware( esp_aes_context *ctx, int crypt_mode) { const uint32_t MODE_DECRYPT_BIT = 4; uint32_t key_word; unsigned mode_reg_base = (crypt_mode == ESP_AES_ENCRYPT) ? 0 : MODE_DECRYPT_BIT; ctx->key_in_hardware = 0; /* Memcpy to avoid potential unaligned access */ for (int i = 0; i < ctx->key_bytes / 4; ++i) { memcpy(&key_word, ctx->key + 4 * i, 4); REG_WRITE(AES_KEY_BASE + i * 4, key_word); ctx->key_in_hardware += 4; } 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(); } } /* * Sets the AES DMA block mode (ECB, CBC, CFB, OFB, GCM, CTR) * and intializes the required registers for that working mode */ static inline void esp_aes_mode_init(esp_aes_mode_t mode) { /* Set the algorithm mode CBC, CFB ... */ REG_WRITE(AES_BLOCK_MODE_REG, mode); /* Presently hard-coding the INC function to 32 bit */ if (mode == ESP_AES_BLOCK_MODE_CTR) { REG_WRITE(AES_INC_SEL_REG, 0); } } /* * Write IV to hardware iv registers */ static inline void esp_aes_set_iv(uint8_t *iv) { uint32_t *reg_addr_buf = (uint32_t *)(AES_IV_BASE); uint32_t iv_word; for (int i = 0; iowner == 0) ) { break; } } } /* Init DMA related registers for AES operation */ static void esp_aes_dma_init(lldesc_t *input, lldesc_t *output) { /* Enable DMA mode */ REG_WRITE(AES_DMA_ENABLE_REG, 1); /* 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)(input))&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)(output))&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); } static int esp_aes_process_dma(esp_aes_context *ctx, const unsigned char *input, unsigned char *output, size_t len, uint8_t *stream_out); /* Output buffers in external ram needs to be 16-byte aligned and DMA cant access input in the iCache mem range, reallocate them into internal memory and encrypt in chunks to avoid having to malloc too big of a buffer */ static int esp_aes_process_dma_ext_ram(esp_aes_context *ctx, const unsigned char *input, unsigned char *output, size_t len, uint8_t *stream_out, bool realloc_input, bool realloc_output) { size_t chunk_len; int ret = 0; int offset = 0; unsigned char *input_buf = NULL; unsigned char *output_buf = NULL; const unsigned char *dma_input; chunk_len = MIN(AES_MAX_CHUNK_WRITE_SIZE, len); if (realloc_input) { input_buf = heap_caps_malloc(chunk_len, MALLOC_CAP_DMA); if (input_buf == NULL) { ESP_LOGE(TAG, "Failed to allocate memory"); ret = -1; goto cleanup; } } if (realloc_output) { output_buf = heap_caps_malloc(chunk_len, MALLOC_CAP_DMA); if (output_buf == NULL) { ESP_LOGE(TAG, "Failed to allocate memory"); ret = -1; goto cleanup; } } else { output_buf = output; } while (len) { chunk_len = MIN(AES_MAX_CHUNK_WRITE_SIZE, len); /* If input needs realloc then copy it, else use the input with offset*/ if (realloc_input) { memcpy(input_buf, input + offset, chunk_len); dma_input = input_buf; } else { dma_input = input + offset; } if (esp_aes_process_dma(ctx, dma_input, output_buf, chunk_len, stream_out) != 0) { ret = -1; goto cleanup; } if (realloc_output) { memcpy(output + offset, output_buf, chunk_len); } else { output_buf = output + offset + chunk_len; } len -= chunk_len; offset += chunk_len; } cleanup: if (realloc_input) { free(input_buf); } if (realloc_output) { free(output_buf); } return ret; } /* Encrypt/decrypt the input using DMA */ static int esp_aes_process_dma(esp_aes_context *ctx, const unsigned char *input, unsigned char *output, size_t len, uint8_t *stream_out) { lldesc_t stream_in_desc, stream_out_desc; lldesc_t *in_desc_head, *out_desc_head; lldesc_t *out_desc_tail = NULL; /* pointer to the final output descriptor */ lldesc_t *block_desc = NULL, *block_in_desc = NULL, *block_out_desc = NULL; size_t lldesc_num; 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 char *non_icache_input = NULL; unsigned blocks = (block_bytes / AES_BLOCK_BYTES) + ((stream_bytes > 0) ? 1 : 0); bool use_intr = false; bool input_needs_realloc = false; bool output_needs_realloc = false; int ret = 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, len); return MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH; } if (block_bytes > 0) { /* Flush cache if input in external ram */ #if (CONFIG_SPIRAM_USE_CAPS_ALLOC || CONFIG_SPIRAM_USE_MALLOC) if (esp_ptr_external_ram(input)) { Cache_WriteBack_All(); } if (esp_ptr_external_ram(output)) { if (((intptr_t)(output) & 0xF) != 0) { // Non aligned ext-mem buffer output_needs_realloc = true; } } #endif /* DMA cannot access memory in the iCache range, copy input to internal ram */ if (!esp_ptr_dma_ext_capable(input) && !esp_ptr_dma_capable(input)) { input_needs_realloc = true; } if (!esp_ptr_dma_ext_capable(output) && !esp_ptr_dma_capable(output)) { output_needs_realloc = true; } /* If either input or output is unaccessible to the DMA then they need to be reallocated */ if (input_needs_realloc || output_needs_realloc) { return esp_aes_process_dma_ext_ram(ctx, input, output, len, stream_out, input_needs_realloc, output_needs_realloc); } /* Set up dma descriptors for input and output */ lldesc_num = lldesc_get_required_num(block_bytes); /* Allocate both in and out descriptors to save a malloc/free per function call */ block_desc = heap_caps_malloc(sizeof(lldesc_t) * lldesc_num * 2, MALLOC_CAP_DMA); if (block_desc == NULL) { ESP_LOGE(TAG, "Failed to allocate memory"); ret = -1; goto cleanup; } block_in_desc = block_desc; block_out_desc = block_desc + lldesc_num; lldesc_setup_link(block_in_desc, input, block_bytes, 0); lldesc_setup_link(block_out_desc, output, block_bytes, 0); out_desc_tail = &block_out_desc[lldesc_num - 1]; } /* Any leftover bytes which are appended as an additional DMA list */ if (stream_bytes > 0) { memcpy(stream_in, input + block_bytes, stream_bytes); lldesc_setup_link(&stream_in_desc, stream_in, AES_BLOCK_BYTES, 0); lldesc_setup_link(&stream_out_desc, stream_out, AES_BLOCK_BYTES, 0); if (block_bytes > 0) { /* Link with block descriptors*/ block_in_desc[lldesc_num - 1].empty = (uint32_t)&stream_in_desc; block_out_desc[lldesc_num - 1].empty = (uint32_t)&stream_out_desc; } out_desc_tail = &stream_out_desc; } // 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; esp_aes_dma_init(in_desc_head, out_desc_head); /* Write the number of blocks */ REG_WRITE(AES_BLOCK_NUM_REG, blocks); #if defined (CONFIG_MBEDTLS_AES_USE_INTERRUPT) /* Only use interrupt for long AES operations */ if (len > AES_DMA_INTR_TRIG_LEN) { use_intr = true; if (esp_aes_isr_initialise() == ESP_FAIL) { ret = -1; goto cleanup; } } else #endif { REG_WRITE(AES_INT_ENA_REG, 0); } /* Start AES operation */ REG_WRITE(AES_TRIGGER_REG, 1); esp_aes_dma_wait_complete(use_intr, out_desc_tail); #if (CONFIG_SPIRAM_USE_CAPS_ALLOC || CONFIG_SPIRAM_USE_MALLOC) if (block_bytes > 0) { if (esp_ptr_external_ram(output)) { Cache_Invalidate_DCache_All(); } } #endif REG_WRITE(AES_DMA_EXIT_REG, 0); /* Disable DMA mode */ REG_WRITE(AES_DMA_ENABLE_REG, 0); if (stream_bytes > 0) { memcpy(output + block_bytes, stream_out, stream_bytes); } cleanup: free(non_icache_input); free(block_desc); return ret; } static int esp_aes_validate_input(esp_aes_context *ctx, const unsigned char *input, unsigned char *output ) { if (!ctx) { ESP_LOGE(TAG, "No AES context supplied"); return -1; } if (!input) { ESP_LOGE(TAG, "No input supplied"); return -1; } if (!output) { ESP_LOGE(TAG, "No output supplied"); return -1; } 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 (esp_aes_validate_input(ctx, input, output)) { return -1; } 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); esp_aes_mode_init(ESP_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 (esp_aes_validate_input(ctx, input, output)) { return -1; } 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); esp_aes_mode_init(ESP_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 (esp_aes_validate_input(ctx, input, output)) { return -1; } 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); esp_aes_mode_init(ESP_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 ) { int r = 0; if (esp_aes_validate_input(ctx, input, output)) { return -1; } if (!iv) { ESP_LOGE(TAG, "No IV supplied"); return -1; } /* For CBC input length should be multiple of * AES BLOCK BYTES * */ if ( (length % AES_BLOCK_BYTES) || (length == 0) ) { 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); esp_aes_mode_init(ESP_AES_BLOCK_MODE_CBC); esp_aes_set_iv(iv); r = esp_aes_process_dma(ctx, input, output, length, NULL); if (r != 0) { esp_aes_release_hardware(); return r; } esp_aes_get_iv(iv); esp_aes_release_hardware(); return r; } /* * 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]; int r = 0; size_t block_bytes = length - (length % AES_BLOCK_BYTES); if (esp_aes_validate_input(ctx, input, output)) { return -1; } if (!iv) { ESP_LOGE(TAG, "No IV supplied"); return -1; } if (!valid_key_length(ctx)) { return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH; } /* The DMA engine will only output correct IV if it runs full blocks of input in CFB8 mode */ esp_aes_acquire_hardware(); if (block_bytes > 0) { ctx->key_in_hardware = 0; esp_aes_setkey_hardware(ctx, mode); esp_aes_mode_init(ESP_AES_BLOCK_MODE_CFB8); esp_aes_set_iv(iv); r = esp_aes_process_dma(ctx, input, output, block_bytes, NULL); esp_aes_get_iv(iv); if (r != 0) { esp_aes_release_hardware(); return r; } length -= block_bytes; input += block_bytes; output += block_bytes; } // Process remaining bytes block-at-a-time in ECB mode if (length > 0) { ctx->key_in_hardware = 0; esp_aes_setkey_hardware(ctx, MBEDTLS_AES_ENCRYPT); esp_aes_mode_init(ESP_AES_BLOCK_MODE_ECB); while ( length-- ) { memcpy( ov, iv, 16 ); r = esp_aes_process_dma(ctx, iv, iv, AES_BLOCK_BYTES, NULL); if (r != 0) { esp_aes_release_hardware(); return r; } 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 r; } /* * 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; int r = 0; size_t stream_bytes = 0; size_t n; if (esp_aes_validate_input(ctx, input, output)) { return -1; } if (!iv) { ESP_LOGE(TAG, "No IV supplied"); return -1; } if (!iv_off) { ESP_LOGE(TAG, "No IV offset supplied"); return -1; } if (!valid_key_length(ctx)) { return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH; } n = *iv_off; /* First process the *iv_off bytes * which are pending from the previous call to this API */ while (n > 0 && length > 0) { if (mode == MBEDTLS_AES_ENCRYPT) { iv[n] = *output++ = *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(); ctx->key_in_hardware = 0; esp_aes_setkey_hardware(ctx, mode); esp_aes_mode_init(ESP_AES_BLOCK_MODE_CFB128); esp_aes_set_iv(iv); r = esp_aes_process_dma(ctx, input, output, length, iv); if (r != 0) { esp_aes_release_hardware(); return r; } 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); } 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 r; } /* * 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 r = 0; size_t n; size_t stream_bytes = 0; if (esp_aes_validate_input(ctx, input, output)) { return -1; } if (!iv) { ESP_LOGE(TAG, "No IV supplied"); return -1; } if (!iv_off) { ESP_LOGE(TAG, "No IV offset supplied"); return -1; } n = *iv_off; /* If there is an offset then use the output of the previous AES block (the updated IV) to calculate the new output */ while (n > 0 && length > 0) { *output++ = (*input++ ^ iv[n]); n = (n + 1) & 0xF; length--; } if (length > 0) { stream_bytes = (length % AES_BLOCK_BYTES); esp_aes_acquire_hardware(); ctx->key_in_hardware = 0; esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT); esp_aes_mode_init(ESP_AES_BLOCK_MODE_OFB); esp_aes_set_iv(iv); r = esp_aes_process_dma(ctx, input, output, length, iv); if (r != 0) { esp_aes_release_hardware(); return r; } esp_aes_get_iv(iv); esp_aes_release_hardware(); } *iv_off = n + stream_bytes; return r; } /* * 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 r = 0; size_t n; if (esp_aes_validate_input(ctx, input, output)) { return -1; } if (!nonce_counter) { ESP_LOGE(TAG, "No nonce supplied"); return -1; } if (!nc_off) { ESP_LOGE(TAG, "No nonce offset supplied"); return -1; } n = *nc_off; if (!valid_key_length(ctx)) { return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH; } /* Process any unprocessed bytes left in stream block from last operation */ while (n > 0 && length > 0) { *output++ = (unsigned char)(*input++ ^ stream_block[n]); n = (n + 1) & 0xF; length--; } if (length > 0) { esp_aes_acquire_hardware(); ctx->key_in_hardware = 0; esp_aes_setkey_hardware(ctx, ESP_AES_DECRYPT); esp_aes_mode_init(ESP_AES_BLOCK_MODE_CTR); esp_aes_set_iv(nonce_counter); r = esp_aes_process_dma(ctx, input, output, length, stream_block); if (r != 0) { esp_aes_release_hardware(); return r; } esp_aes_get_iv(nonce_counter); esp_aes_release_hardware(); } *nc_off = n + (length % AES_BLOCK_BYTES); return r; } static void esp_gcm_ghash(esp_gcm_context *ctx, const unsigned char *x, size_t x_len, uint8_t *z); /* * Calculates the Initial Counter Block, J0 * and copies to to the esp_gcm_context */ static void esp_gcm_derive_J0(esp_gcm_context *ctx) { uint8_t len_buf[16]; memset(ctx->J0, 0, AES_BLOCK_BYTES); memset(len_buf, 0, AES_BLOCK_BYTES); /* If IV is 96 bits J0 = ( IV || 0^31 || 1 ) */ if (ctx->iv_len == 12) { memcpy(ctx->J0, ctx->iv, ctx->iv_len); ctx->J0[AES_BLOCK_BYTES - 1] |= 1; } else { /* For IV != 96 bit, J0 = GHASH(IV || 0[s+64] || [len(IV)]64) */ /* First calculate GHASH on IV */ esp_gcm_ghash(ctx, ctx->iv, ctx->iv_len, ctx->J0); /* Next create 128 bit block which is equal to 64 bit 0 + iv length truncated to 64 bits */ ESP_PUT_BE64(len_buf + 8, ctx->iv_len * 8); /* Calculate GHASH on last block */ esp_gcm_ghash(ctx, len_buf, 16, ctx->J0); } } /* * Increment J0 as per GCM spec, by applying the Standard Incrementing Function INC_32 to it. * j is the counter which needs to be incremented which is * copied to ctx->J0 after incrementing */ static void increment32_j0(esp_gcm_context *ctx, uint8_t *j) { uint8_t j_len = AES_BLOCK_BYTES; memcpy(j, ctx->J0, AES_BLOCK_BYTES); if (j) { for (uint32_t i = j_len; i > (j_len - 4); i--) { if (++j[i - 1] != 0) { break; } } memcpy(ctx->J0, j, AES_BLOCK_BYTES); } } /* Function to xor two data blocks */ static void xor_data(uint8_t *d, const uint8_t *s) { for (int i = 0; i < AES_BLOCK_BYTES; i++) { d[i] ^= s[i]; } } /* * 32-bit integer manipulation macros (big endian) */ #ifndef GET_UINT32_BE #define GET_UINT32_BE(n,b,i) \ { \ (n) = ( (uint32_t) (b)[(i) ] << 24 ) \ | ( (uint32_t) (b)[(i) + 1] << 16 ) \ | ( (uint32_t) (b)[(i) + 2] << 8 ) \ | ( (uint32_t) (b)[(i) + 3] ); \ } #endif #ifndef PUT_UINT32_BE #define PUT_UINT32_BE(n,b,i) \ { \ (b)[(i) ] = (unsigned char) ( (n) >> 24 ); \ (b)[(i) + 1] = (unsigned char) ( (n) >> 16 ); \ (b)[(i) + 2] = (unsigned char) ( (n) >> 8 ); \ (b)[(i) + 3] = (unsigned char) ( (n) ); \ } #endif /* Based on MbedTLS's implemenation * * Precompute small multiples of H, that is set * HH[i] || HL[i] = H times i, * where i is seen as a field element as in [MGV], ie high-order bits * correspond to low powers of P. The result is stored in the same way, that * is the high-order bit of HH corresponds to P^0 and the low-order bit of HL * corresponds to P^127. */ static int gcm_gen_table( esp_gcm_context *ctx ) { int i, j; uint64_t hi, lo; uint64_t vl, vh; unsigned char *h; h = ctx->H; /* pack h as two 64-bits ints, big-endian */ GET_UINT32_BE( hi, h, 0 ); GET_UINT32_BE( lo, h, 4 ); vh = (uint64_t) hi << 32 | lo; GET_UINT32_BE( hi, h, 8 ); GET_UINT32_BE( lo, h, 12 ); vl = (uint64_t) hi << 32 | lo; /* 8 = 1000 corresponds to 1 in GF(2^128) */ ctx->HL[8] = vl; ctx->HH[8] = vh; /* 0 corresponds to 0 in GF(2^128) */ ctx->HH[0] = 0; ctx->HL[0] = 0; for( i = 4; i > 0; i >>= 1 ) { uint32_t T = ( vl & 1 ) * 0xe1000000U; vl = ( vh << 63 ) | ( vl >> 1 ); vh = ( vh >> 1 ) ^ ( (uint64_t) T << 32); ctx->HL[i] = vl; ctx->HH[i] = vh; } for( i = 2; i <= 8; i *= 2 ) { uint64_t *HiL = ctx->HL + i, *HiH = ctx->HH + i; vh = *HiH; vl = *HiL; for( j = 1; j < i; j++ ) { HiH[j] = vh ^ ctx->HH[j]; HiL[j] = vl ^ ctx->HL[j]; } } return( 0 ); } /* * Shoup's method for multiplication use this table with * last4[x] = x times P^128 * where x and last4[x] are seen as elements of GF(2^128) as in [MGV] */ static const uint64_t last4[16] = { 0x0000, 0x1c20, 0x3840, 0x2460, 0x7080, 0x6ca0, 0x48c0, 0x54e0, 0xe100, 0xfd20, 0xd940, 0xc560, 0x9180, 0x8da0, 0xa9c0, 0xb5e0 }; /* Based on MbedTLS's implemenation * * Sets output to x times H using the precomputed tables. * x and output are seen as elements of GF(2^128) as in [MGV]. */ static void gcm_mult( esp_gcm_context *ctx, const unsigned char x[16], unsigned char output[16] ) { int i = 0; unsigned char lo, hi, rem; uint64_t zh, zl; lo = x[15] & 0xf; zh = ctx->HH[lo]; zl = ctx->HL[lo]; for( i = 15; i >= 0; i-- ) { lo = x[i] & 0xf; hi = x[i] >> 4; if( i != 15 ) { rem = (unsigned char) zl & 0xf; zl = ( zh << 60 ) | ( zl >> 4 ); zh = ( zh >> 4 ); zh ^= (uint64_t) last4[rem] << 48; zh ^= ctx->HH[lo]; zl ^= ctx->HL[lo]; } rem = (unsigned char) zl & 0xf; zl = ( zh << 60 ) | ( zl >> 4 ); zh = ( zh >> 4 ); zh ^= (uint64_t) last4[rem] << 48; zh ^= ctx->HH[hi]; zl ^= ctx->HL[hi]; } PUT_UINT32_BE( zh >> 32, output, 0 ); PUT_UINT32_BE( zh, output, 4 ); PUT_UINT32_BE( zl >> 32, output, 8 ); PUT_UINT32_BE( zl, output, 12 ); } /* Update the key value in gcm context */ int esp_aes_gcm_setkey( esp_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 z = GHASH(x) using h0 hash key */ static void esp_gcm_ghash(esp_gcm_context *ctx, const unsigned char *x, size_t x_len, uint8_t *z) { uint8_t tmp[AES_BLOCK_BYTES]; memset(tmp, 0, AES_BLOCK_BYTES); /* GHASH(X) is calculated on input string which is multiple of 128 bits * If input string bit length is not multiple of 128 bits it needs to * be padded by 0 * * Steps: * 1. Let X1, X2, ... , Xm-1, Xm denote the unique sequence of blocks such * that X = X1 || X2 || ... || Xm-1 || Xm. * 2. Let Y0 be the “zero block,” 0128. * 3. Fori=1,...,m,letYi =(Yi-1 ^ Xi)•H. * 4. Return Ym */ /* If input bit string is >= 128 bits, process full 128 bit blocks */ while (x_len >= AES_BLOCK_BYTES) { xor_data(z, x); gcm_mult(ctx, z, z); x += AES_BLOCK_BYTES; x_len -= AES_BLOCK_BYTES; } /* If input bit string is not multiple of 128 create last 128 bit * block by padding necessary 0s */ if (x_len) { memcpy(tmp, x, x_len); xor_data(z, tmp); gcm_mult(ctx, z, z); } } /* Function to init AES GCM context to zero */ void esp_aes_gcm_init( esp_gcm_context *ctx) { if (ctx == NULL) { return; } bzero(ctx, sizeof(esp_gcm_context)); ctx->gcm_state = ESP_AES_GCM_STATE_INIT; } /* Function to clear AES-GCM context */ void esp_aes_gcm_free( esp_gcm_context *ctx) { if (ctx == NULL) { return; } bzero(ctx, sizeof(esp_gcm_context)); } /* Setup AES-GCM */ int esp_aes_gcm_starts( esp_gcm_context *ctx, int mode, const unsigned char *iv, size_t iv_len, const unsigned char *aad, size_t aad_len ) { /* IV and AD are limited to 2^64 bits, so 2^61 bytes */ /* IV is not allowed to be zero length */ if ( iv_len == 0 || ( (uint64_t) iv_len ) >> 61 != 0 || ( (uint64_t) aad_len ) >> 61 != 0 ) { return ( MBEDTLS_ERR_GCM_BAD_INPUT ); } if (!ctx) { ESP_LOGE(TAG, "No AES context supplied"); return -1; } if (!iv) { ESP_LOGE(TAG, "No IV supplied"); return -1; } if ( (aad_len > 0) && !aad) { ESP_LOGE(TAG, "No aad supplied"); return -1; } /* Initialize AES-GCM context */ memset(ctx->ghash, 0, sizeof(ctx->ghash)); ctx->data_len = 0; ctx->iv = iv; ctx->iv_len = iv_len; ctx->aad = aad; ctx->aad_len = aad_len; ctx->mode = mode; /* H and the lookup table are only generated once per ctx */ if (ctx->gcm_state == ESP_AES_GCM_STATE_INIT) { /* Lock the AES engine to calculate ghash key H in hardware */ esp_aes_acquire_hardware(); esp_aes_setkey_hardware( &ctx->aes_ctx, mode); esp_aes_mode_init(ESP_AES_BLOCK_MODE_GCM); /* Enable DMA mode */ REG_WRITE(AES_DMA_ENABLE_REG, 1); REG_WRITE(AES_TRIGGER_REG, 1); while (REG_READ(AES_STATE_REG) != AES_STATE_IDLE); memcpy(ctx->H, (uint8_t *)AES_H_BASE, AES_BLOCK_BYTES); esp_aes_release_hardware(); gcm_gen_table(ctx); } ctx->gcm_state = ESP_AES_GCM_STATE_START; /* Once H is obtained we need to derive J0 (Initial Counter Block) */ esp_gcm_derive_J0(ctx); /* The initial counter block keeps updating during the esp_gcm_update call * however to calculate final authentication tag T we need original J0 * so we make a copy here */ memcpy(ctx->ori_j0, ctx->J0, 16); esp_gcm_ghash(ctx, ctx->aad, ctx->aad_len, ctx->ghash); return ( 0 ); } /* Perform AES-GCM operation */ int esp_aes_gcm_update( esp_gcm_context *ctx, size_t length, const unsigned char *input, unsigned char *output ) { size_t nc_off = 0; uint8_t nonce_counter[AES_BLOCK_BYTES] = {0}; uint8_t stream[AES_BLOCK_BYTES] = {0}; if (!ctx) { ESP_LOGE(TAG, "No GCM context supplied"); return -1; } if (!input) { ESP_LOGE(TAG, "No input supplied"); return -1; } if (!output) { ESP_LOGE(TAG, "No output supplied"); return -1; } if ( output > input && (size_t) ( output - input ) < length ) { return ( MBEDTLS_ERR_GCM_BAD_INPUT ); } /* If this is the first time esp_gcm_update is getting called * calculate GHASH on aad and preincrement the ICB */ if (ctx->gcm_state == ESP_AES_GCM_STATE_START) { /* Jo needs to be incremented first time, later the CTR * operation will auto update it */ increment32_j0(ctx, nonce_counter); ctx->gcm_state = ESP_AES_GCM_STATE_UPDATE; } else if (ctx->gcm_state == ESP_AES_GCM_STATE_UPDATE) { memcpy(nonce_counter, ctx->J0, AES_BLOCK_BYTES); } /* Perform intermediate GHASH on "encrypted" data during decryption */ if (ctx->mode == ESP_AES_DECRYPT) { esp_gcm_ghash(ctx, input, length, ctx->ghash); } /* Output = GCTR(J0, Input): Encrypt/Decrypt the input */ esp_aes_crypt_ctr(&ctx->aes_ctx, length, &nc_off, nonce_counter, stream, input, output); /* ICB gets auto incremented after GCTR operation here so update the context */ memcpy(ctx->J0, nonce_counter, AES_BLOCK_BYTES); /* Keep updating the length counter for final tag calculation */ ctx->data_len += length; /* Perform intermediate GHASH on "encrypted" data during encryption*/ if (ctx->mode == ESP_AES_ENCRYPT) { esp_gcm_ghash(ctx, output, length, ctx->ghash); } return 0; } /* Function to read the tag value */ int esp_aes_gcm_finish( esp_gcm_context *ctx, unsigned char *tag, size_t tag_len ) { size_t nc_off = 0; uint8_t len_block[AES_BLOCK_BYTES] = {0}; if ( tag_len > 16 || tag_len < 4 ) { return ( MBEDTLS_ERR_GCM_BAD_INPUT ); } /* Calculate final GHASH on aad_len, data length */ ESP_PUT_BE64(len_block, ctx->aad_len * 8); ESP_PUT_BE64(len_block + 8, ctx->data_len * 8); esp_gcm_ghash(ctx, len_block, AES_BLOCK_BYTES, ctx->ghash); /* Tag T = GCTR(J0, ) where T is truncated to tag_len */ esp_aes_crypt_ctr(&ctx->aes_ctx, tag_len, &nc_off, ctx->ori_j0, 0, ctx->ghash, tag); return 0; } int esp_aes_gcm_crypt_and_tag( esp_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_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 ); }