#include <esp8266.h>
#include <string.h>
#include "crypto/crypto.h"
#include "crypto/aes.h"
#include "crypto/sha256.h"
#include "crypto/hmac-sha256.h"
#include "user_config.h"

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Functions
void	init_aes_hmac_combined (uint8_t *key)

ICACHE_FLASH_ATTR size_t	encrypt_aes_hmac_combined (uint8_t dst, uint8_t topic, size_t topic_l, uint8_t *message, size_t message_l)

ICACHE_FLASH_ATTR size_t	decrypt_aes_hmac_combined (uint8_t dst, uint8_t topic, size_t topic_l, uint8_t *message, size_t message_l)

Variables
uint8_t	sha256_hash [SHA256_DIGEST_LENGTH]

uint8_t	aes_key [16]

uint8_t	hmac_sha256_key [16]

Function Documentation

◆ decrypt_aes_hmac_combined()

ICACHE_FLASH_ATTR size_t decrypt_aes_hmac_combined	(	uint8_t *	dst,
		uint8_t *	topic,
		size_t	topic_l,
		uint8_t *	message,
		size_t	message_l
	)

Definition at line 99 of file crypto.c.

References AES128_CBC_decrypt_buffer(), aes_key, hmac_sha256_final(), hmac_sha256_init(), hmac_sha256_key, hmac_sha256_update(), memcmp, SHA256_DIGEST_LENGTH, and strlen.

                                                                                                                    {
     hmac_sha256_ctx_t hctx;
     uint8_t calculated_hmac_sha256[SHA256_DIGEST_LENGTH];
 
     // hmac sha256
     hmac_sha256_init(&hctx, hmac_sha256_key, sizeof(hmac_sha256_key));
     hmac_sha256_update(&hctx, topic, topic_l);
     hmac_sha256_update(&hctx, message + SHA256_DIGEST_LENGTH, message_l - SHA256_DIGEST_LENGTH);
     hmac_sha256_final(&hctx, calculated_hmac_sha256);
 
     if (memcmp(calculated_hmac_sha256, message, SHA256_DIGEST_LENGTH) == 0) {
         // hmac sha256 matches
         
         AES128_CBC_decrypt_buffer(dst + 0, message + SHA256_DIGEST_LENGTH + 16, message_l, aes_key, message + SHA256_DIGEST_LENGTH);
         return strlen(dst);
     }
     else {
         return 0;
     }
 }

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◆ encrypt_aes_hmac_combined()

ICACHE_FLASH_ATTR size_t encrypt_aes_hmac_combined	(	uint8_t *	dst,
		uint8_t *	topic,
		size_t	topic_l,
		uint8_t *	message,
		size_t	message_l
	)

Definition at line 68 of file crypto.c.

References AES128_CBC_encrypt_buffer(), aes_key, hmac_sha256_final(), hmac_sha256_init(), hmac_sha256_key, hmac_sha256_update(), ICACHE_FLASH_ATTR, memset, os_get_random(), and SHA256_DIGEST_LENGTH.

Referenced by en61107_received_task(), en61107_request_send(), kmp_received_task(), and kmp_request_send().

                                                                                                                    {
     hmac_sha256_ctx_t hctx;
     int return_l;
 
     // encrypt
     memset(dst, 0, sizeof(dst));
     // get random iv in first 16 bytes of mqtt_message
     os_get_random(dst + SHA256_DIGEST_LENGTH, 16);
 
     // calculate blocks needed for encrypted string
     return_l = message_l;
     if (return_l % 16) {
         return_l = (return_l / 16) * 16 + 16;
     }
     else {
         return_l = (return_l / 16) * 16;
     }
     
     AES128_CBC_encrypt_buffer(dst + SHA256_DIGEST_LENGTH + 16, message, return_l, aes_key, dst + SHA256_DIGEST_LENGTH); // first 32 bytes of mqtt_message contains hmac sha256, next 16 bytes contains IV
     return_l += SHA256_DIGEST_LENGTH + 16;
     
     // hmac sha256
     hmac_sha256_init(&hctx, hmac_sha256_key, sizeof(hmac_sha256_key));
     hmac_sha256_update(&hctx, topic, topic_l);
     hmac_sha256_update(&hctx, dst + SHA256_DIGEST_LENGTH, return_l - SHA256_DIGEST_LENGTH);
     hmac_sha256_final(&hctx, dst);
     
     return return_l;
 }

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◆ init_aes_hmac_combined()

void init_aes_hmac_combined ( uint8_t * key )

Definition at line 22 of file crypto.c.

References _align_32_bit, aes_key, hmac_sha256_key, ICACHE_FLASH_ATTR, memcpy, memset, printf, sha256_hash, sha256_raw(), system_soft_wdt_restart(), and system_soft_wdt_stop().

                                           {
 #ifdef DEBUG
     unsigned int i;
 #endif
     _align_32_bit uint8_t master_key[16];
     
     memcpy(master_key, key, 16);
     
 #ifdef DEBUG
     system_soft_wdt_stop();
     printf("master key: ");
     for (i = 0; i < 16; i++) {
         printf("%02x", key[i]);
     }
     printf("\n");
     system_soft_wdt_restart();
 #endif  
     // generate aes_key and hmac_sha256_key from master_key
     memset(sha256_hash, 0, sizeof(sha256_hash));
     
     sha256_raw(master_key, 16, sha256_hash);
     
     // first 16 bytes is aes key
     memcpy(aes_key, sha256_hash, sizeof(aes_key));
     // last 16 bytes is hmac sha256 key
     memcpy(hmac_sha256_key, sha256_hash + sizeof(aes_key), sizeof(hmac_sha256_key));
     
 #ifdef DEBUG
     system_soft_wdt_stop();
     // print keys
     printf("aes key: ");
     for (i = 0; i < 16; i++) {
         printf("%02x", aes_key[i]);
     }
     printf("\n");
     
     printf("hmac sha256 key: ");
     for (i = 0; i < 16; i++) {
         printf("%02x", hmac_sha256_key[i]);
     }
     printf("\n");
     system_soft_wdt_restart();
 #endif
 }