c++ - Replace std::vector's buffer with a malloc'ed char array -

i have following class holding std::vector resizable "buffer" data.

class packet { public:     struct packetheader     {         size_t datasize = 0;         size_t paddeddatasize = 0;     } header_;      const unsigned char* data() const     {         return &data_[0];     }      unsigned char* data()     {         return &data_[0];     }      /// changes size of data vector     void resize(size_t sz)     {        header_.datasize = sz;          // check if padding needed         if (sz % aes_block_size != 0){             auto padding = aes_block_size - (sz % aes_block_size);                   data_.resize(sz + padding);             (int = 1; <= padding; i++)             {                                data_[(sz + padding) - i] = '\0';             }             header_.paddeddatasize = sz + padding;         } else{                      data_.resize(sz);         }     }  private:         std::vector<unsigned char> data_;    }; 

then i'm performing aes encryption on data before transfering them on network, requires temporary buffer of same size generate ciphertext, has copied vector.

void tcpconnection::send_packet(packet& pkg) {     // cut out unrelevant lines of code      // need temporary buffer encryption     unsigned char* enc_out = (unsigned char*)malloc(pkg.header_.paddeddatasize);      // aes-128 bit cbc encryption     aes_cbc_encrypt(pkg.data(), enc_out, pkg.header_.paddeddatasize);      // need copy data temporary buffer objects vector      memcpy(pkg.data(), enc_out, pkg.header_.paddeddatasize);          free(enc_out);      io_service_.post([this, pkg]() { transmit(pkg); }); } 

this seems rather expensive task. isn't there better way, kind of let vector take ownership of temporary buffer (did understand correctly these new std::move , rvalue move semantics used kind of stuff?)

move semantics can avoid copy.

however instead of malloc'ing buffer encrypted data, use vector. can use std::move replace contents of packet's data_ member.