[Assignment-7] embedded device prototype

This commit is contained in:
Sascha Tommasone 2024-07-06 15:59:40 +02:00 committed by saschato
parent 05ea23459f
commit c99556a595
2 changed files with 132 additions and 0 deletions

View file

@ -0,0 +1,126 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/sha.h>
#include <openssl/ec.h>
#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/pem.h>
#include <openssl/core_names.h>
#include "embedded_device.h"
#define BUFSIZE 16384
typedef struct {
uint8_t *firmware_path;
uint8_t *public_key_path;
} embedded_device_args;
static void syntax_exit() {
fprintf(stderr, "syntax error!\n");
exit(EXIT_FAILURE);
}
static EVP_PKEY *read_public_key(uint8_t *public_key_file, EVP_PKEY **key) {
if(public_key_file == NULL) {
fprintf(stderr, "public_key_file is a null pointer!\n");
}
FILE *fd = fopen(public_key_file, "rb");
if(fd == NULL) {
fprintf(stderr, "failed to open public key file!\n");
return NULL;
}
*key = PEM_read_PUBKEY(fd, key, NULL, NULL);
fclose(fd);
return *key;
}
static void hash_firmware(uint8_t *firmware_path, EVP_MD_CTX **ctx) {
if(firmware_path == NULL) {
fprintf(stderr, "firmware_path is a null pointer!\n");
}
FILE *fd = fopen(firmware_path, "rb");
if(fd == NULL) {
fprintf(stderr, "failed to open firmware!\n");
}
size_t size;
uint8_t buf[BUFSIZE];
while((size = fread(buf, 1, BUFSIZE, fd)) != 0) {
EVP_DigestVerifyUpdate(*ctx, buf, size);
}
fclose(fd);
}
static void read_signature(uint8_t *signature, size_t *signature_size) {
FILE *fd = stdin;
if(fd == NULL) {
fprintf(stderr, "failed to stdin!\n");
}
// TODO: ersmal ne pause :)
}
int main(int argc, char **argv) {
embedded_device_args args = {
.firmware_path = NULL,
.public_key_path = NULL
};
if(argc == 1) {
syntax_exit();
}
for(int i = 1; i < argc; i += 2) {
if((strcmp(argv[i], "-pub") == 0) && (argc - i >= 2)) {
args.public_key_path = argv[i+1];
} else if((strcmp(argv[i], "-firm") == 0) && (argc - i >= 2)) {
args.firmware_path = argv[i+1];
} else {
syntax_exit();
}
}
if((args.firmware_path == NULL) || (args.public_key_path == NULL)) {
fprintf(stderr, "failed to parse arguments");
exit(EXIT_FAILURE);
}
EVP_PKEY *key = NULL;
if(read_public_key(args.public_key_path, &key) == NULL) {
fprintf(stderr, "failed to import public key");
goto clean;
}
EVP_MD_CTX *ctx = EVP_MD_CTX_new();
if (EVP_DigestVerifyInit(ctx, NULL, EVP_sha256(), NULL, key) != 1) {
fprintf(stderr, "failed to initialize context\n");
goto clean;
}
read_signature(NULL, NULL);
goto clean;
hash_firmware(args.firmware_path, &ctx);
if (EVP_DigestVerifyFinal(ctx, NULL, 0) != 1) {
printf("failed to verify firmware signature\n");
goto clean;
}
clean: ;
if(key != NULL)
EVP_PKEY_free(key);
if(ctx != NULL)
EVP_MD_CTX_free(ctx);
return 0;
}

View file

@ -0,0 +1,6 @@
#ifndef EMBEDDED_DEVICE_H
#define EMBEDDED_DEVICE_H
#include <stdint.h>
#endif