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| int decrypt(char *encrypt_content, int encrypt_size, char *key, char *iv, char *dec_content)
{
int result = -1;
EVP_CIPHER_CTX *ctx;
int dec_out[2];
ctx = EVP_CIPHER_CTX_new();
if (ctx == 0)
{
ERR_print_errors_fp(stderr);
}
else
{
if (EVP_DecryptInit_ex(ctx, EVP_aes_128_cbc(), 0, key, iv))
{
if (EVP_DecryptUpdate(ctx, dec_content, dec_out, encrypt_content, encrypt_size))
{
result = dec_out[0];
if (EVP_DecryptFinal_ex(ctx, dec_content + dec_out[0], dec_out))
{
result += dec_out[0];
}
else
{
ERR_print_errors_fp(stderr);
}
}
else
{
ERR_print_errors_fp(stderr);
}
}
else
{
ERR_print_errors_fp(stderr);
}
}
if (ctx != 0)
{
EVP_CIPHER_CTX_free(ctx);
}
return result;
}
int save_to_file(char *filename, char *decode_buffer, int size)
{
FILE *fp = fopen(filename, "w+");
if (NULL == fp)
{
return -1;
}
fwrite(decode_buffer, size, 1, fp);
fclose(fp);
fp = NULL;
return 0;
}
int decode_img(char *buffer, char *dec_file_name)
{
//获取文件大小
int size = ntohl(*(uint32_t *)(buffer + 0xc));
char *decoded_buffer = malloc(size + -0x230);
int decoded_size = decrypt(buffer + 0x240, size + -0x230, buffer + 0x220, buffer + 0x230, decoded_buffer);
if (decoded_size > 0)
{
return save_to_file(dec_file_name, decoded_buffer, decoded_size);
}
return -1;
}
|