C++ EVP_EncriptUpdate 重写堆栈？

Question

我有这个代码

.....

const EVP_CIPHER * cipher = EVP_des_ecb();
uint8_t ot_byte,st_byte;
EVP_CIPHER_CTX ctx;
int trash;
EVP_EncryptInit(&ctx,cipher, key, iv);
cout << size - offset << endl;
int i=0;
for (; i < size - offset ;i++){
    check = read(input_fd,&ot_byte,1);
    cout << (i < size - offset) << " " << i << endl;
      EVP_EncryptUpdate(&ctx,  &st_byte, &trash, &ot_byte, 1);
      check = write(output_fd,&st_byte,1);
}
cout << (i < size - offset) << " " << i << endl;
close(output_fd);
close(output_fd);

输出是

当我"comment off" EVP 更新函数时，循环会经历所有 702000 次迭代。错误在哪里？ EVP 是否有可能以某种方式落后于其缓冲区并损坏堆栈数据？

Answer 1

uint8_t类型会小，这些函数return至少8个字节

C++ EVP_EncriptUpdate 重写堆栈？

C++ EVP_EncriptUpdate rewriting stack?

c++

stack

evp-cipher