如何檢查輸入的密碼是否在botan加密中是否正確

Question

我有一個加密和解密文件的代碼，代碼效果很好，但問題是當我嘗試使用不正確的密碼解密文件時，一個錯誤，執行解密導致與原始文件不同的文件。是否可以檢查在解密中輸入的密碼是否與加密中使用的密碼相同？

void AES::Encrypt(SymmetricKey key, InitializationVector iv, string inFilename, string outFilename) 
{ 
    ifstream in(inFilename.c_str(),std::ios::binary); 
    ofstream out(outFilename.c_str(),std::ios::binary); 

    QFile* file = new QFile(inFilename.c_str()); 

    qint64 size = file->size(); 
    qint64 i = 0; 
    percent = -1; 

    Pipe pipe(get_cipher("AES-256/CBC", key, iv,ENCRYPTION),new DataSink_Stream(out)); 
    pipe.start_msg(); 
    SecureBuffer<byte, 4096> buffer; 
    while(in.good()) 
    { 
     in.read((char*)&buffer[0], buffer.size()); 
     const size_t got_from_infile = in.gcount(); 
     pipe.write(buffer, got_from_infile); 
     i += got_from_infile; 
     int p = ((i * 100)/size); 
     if (p != percent) 
     { 
      percent = p; 
      emit progress(percent); 
     } 
     if(in.eof()) pipe.end_msg(); 
     while(pipe.remaining() > 0) 
     { 
      const size_t buffered = pipe.read(buffer, buffer.size()); 
      out.write((const char*)&buffer[0], buffered); 
     } 
    } 
    out.flush(); 
    out.close(); 
    in.close(); 

    qDebug() << "Encrypted!"; 
} 

void AES::Decrypt(SymmetricKey key, InitializationVector iv, string inFilename, string outFilename) 
{ 
    ifstream in(inFilename.c_str(),std::ios::binary); 
    ofstream out(outFilename.c_str(),std::ios::binary); 

    QFile* file = new QFile(inFilename.c_str()); 

    qint64 size = file->size(); 
    qint64 i = 0; 
    percent = -1; 

    Pipe pipe(get_cipher("AES-256/CBC", key, iv,DECRYPTION),new DataSink_Stream(out)); 
    pipe.start_msg(); 
    SecureBuffer<byte, 4096> buffer; 
    while(in.good()) 
    { 
     in.read((char*)&buffer[0], buffer.size()); 
     const size_t got_from_infile = in.gcount(); 
     pipe.write(buffer, got_from_infile); 
     i += got_from_infile; 
     int p = ((i * 100)/size); 
     if (p != percent) 
     { 
      percent = p; 
      emit progress(percent); 
     } 
     if(in.eof()) pipe.end_msg(); 
     while(pipe.remaining() > 0) 
     { 
      const size_t buffered = pipe.read(buffer, buffer.size()); 
      out.write((const char*)&buffer[0], buffered); 
     } 
    } 
    out.flush(); 
    out.close(); 
    in.close(); 

    qDebug() << "Decrypted!"; 
} 

Answer 1

加密時，首先將未加密文件的全部內容的散列附加到其末尾，然後加密新文件。因此加密文件比未加密文件大幾個字節。

解密後，首先檢查最後的散列是否有效，然後將其從文件中除去以獲取原始內容。