diff options
| -rw-r--r-- | main.c | 23 |
1 files changed, 11 insertions, 12 deletions
@@ -16,25 +16,28 @@ int pkcs7_check_pad(const char *buf, size_t n); typedef struct s_key_search_ctx { /* first 8 bytes and the last 8 bytes of the ciphertext * in encrypted QQ flash image */ - uint64_t ciphertext[2]; + const char *ciphertext; /* if routine `yield_possible_key` returns true, * the possible 64-bit DES key will be stored here */ uint64_t yield; /* 4 byte effective key space */ uint32_t next_possible_key; + /* length of ciphertext */ + uint32_t len; bool finished; } key_search_ctx; /* constructor of type `key_search_ctx` */ void new_key_search_ctx( key_search_ctx *ctx, - uint64_t ciphertext[2], + const char *ciphertext, + uint32_t ciphertext_len, uint32_t a ) { ctx->finished = false; ctx->next_possible_key = a; - ctx->ciphertext[0] = ciphertext[0]; - ctx->ciphertext[1] = ciphertext[1]; + ctx->ciphertext = ciphertext; + ctx->len = ciphertext_len; } /* search key in range [a, b), returns false if @@ -79,7 +82,7 @@ bool yield_possible_key( } /* decrypt the first 8 bytes */ if (des_ecb_decrypt( - (const unsigned char *) (&ctx->ciphertext[0]), + (const unsigned char *) (ctx->ciphertext), (unsigned char *) &plaintext, (const symmetric_key *) &skey ) != CRYPT_OK) @@ -90,7 +93,7 @@ bool yield_possible_key( /* decrypt the last 8 bytes */ if (des_ecb_decrypt( - (const unsigned char *) (&ctx->ciphertext[1]), + (const unsigned char *) (ctx->ciphertext + ctx->len - 8), (unsigned char *) &plaintext, (const symmetric_key *) &skey ) != CRYPT_OK) @@ -135,7 +138,7 @@ typedef struct s_thread_param { /* if a worker find this to be true, it will terminate */ atomic_bool key_found; /* shared across workers */ -const char *ciphertext; +const char * volatile ciphertext; /* should not be modified by workers */ uint32_t ciphertext_len; /* the result generated by a lucky worker */ @@ -148,11 +151,7 @@ int thread_worker(thread_param *param) { key_search_ctx ctx; const uint32_t b = param->b; /* search end */ uint32_t ciphertext_length = ciphertext_len; - uint64_t prefilter_ciphertext[2] = { - *(uint64_t *) ciphertext, - *((uint64_t *) (ciphertext + ciphertext_length) - 1) - }; - new_key_search_ctx(&ctx, prefilter_ciphertext, param->a); + new_key_search_ctx(&ctx, ciphertext, ciphertext_length, param->a); char *plaintext = malloc(ciphertext_length); if (plaintext == NULL) { perror("malloc"); |