My program could encrypt text and save it in a file, and decrypt the cipher text after getting from the file.

But I keep on getting this error

terminate called after throwing an instance of 'CryptoPP::InvalidCiphertext'
what(): StreamTransformationFilter: ciphertext length is not a multiple of block size
exited with code 3
Here my encrypt code, the reason I seperate them to different files is because I'm trying to remove this annoying error.

Qt Code: 
  1. byte key[ CryptoPP::AES::DEFAULT_KEYLENGTH ], iv[ CryptoPP::AES::BLOCKSIZE ];
  2.                   memset( key, 0x00, CryptoPP::AES::DEFAULT_KEYLENGTH );
  3.                   memset( iv, 0x00, CryptoPP::AES::BLOCKSIZE );
  4.                   string ciphertext[7];
  5.  
  6.  
  7.  
  8.                   CryptoPP::AES::Encryption aesEncryption(key, CryptoPP::AES::DEFAULT_KEYLENGTH);
  9.                   CryptoPP::CBC_Mode_ExternalCipher::Encryption cbcEncryption( aesEncryption, iv );
  10.  
  11.                   CryptoPP::StreamTransformationFilter stfEncryptor(cbcEncryption, new CryptoPP::StringSink( ciphertext[0] ) );
  12.                   stfEncryptor.Put( reinterpret_cast<const unsigned char*>( line[0].c_str() ), line[0].length() + 1 );
  13.                   stfEncryptor.MessageEnd();
  14.  
  15.                   ofstream outfile("./QA.dll");
  16.                   outfile << ciphertext[0] << endl;
  17.  
  18.  
  19.  
  20.                   CryptoPP::AES::Encryption aesEncryption1(key, CryptoPP::AES::DEFAULT_KEYLENGTH);
  21.                   CryptoPP::CBC_Mode_ExternalCipher::Encryption cbcEncryption1( aesEncryption1, iv );
  22.  
  23.                   CryptoPP::StreamTransformationFilter stfEncryptor1(cbcEncryption1, new CryptoPP::StringSink( ciphertext[1] ) );
  24.                   stfEncryptor1.Put( reinterpret_cast<const unsigned char*>( line[1].c_str() ), line[1].length() + 1 );
  25.                   stfEncryptor1.MessageEnd();
  26.  
  27.                   ofstream outfile1("./QF.dll");
  28.                   outfile1 << ciphertext[1] << endl;
  29.  
  30.  
  31.  
  32.                   CryptoPP::AES::Encryption aesEncryption2(key, CryptoPP::AES::DEFAULT_KEYLENGTH);
  33.                   CryptoPP::CBC_Mode_ExternalCipher::Encryption cbcEncryption2( aesEncryption2, iv );
  34.  
  35.                   CryptoPP::StreamTransformationFilter stfEncryptor2(cbcEncryption2, new CryptoPP::StringSink( ciphertext[2] ) );
  36.                   stfEncryptor2.Put( reinterpret_cast<const unsigned char*>( line[2].c_str() ), line[2].length() + 1 );
  37.                   stfEncryptor2.MessageEnd();
  38.  
  39.                   ofstream outfile2("./QG.dll");
  40.                   outfile2 << ciphertext[2] << endl;
  41. ....
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Here decrypt's code, I made key1, key2 is also because of trying to remove the error

Qt Code: 
  1. ifstream infile("./Q.dll");
  2.                         if (!infile.is_open())
  3.                             return 1;
  4.                         getline(infile, ciphertext[0]);
  5.  
  6.                         ifstream infile1("./QF.dll");
  7.                         if (!infile1.is_open())
  8.                             return 1;
  9.                         getline(infile1, ciphertext[1]);
  10.  
  11.                         ifstream infile2("./QG.dll");
  12.                         if (!infile2.is_open())
  13.                             return 1;
  14.                         getline(infile2, ciphertext[2]);
  15. ...
  16.  
  17.                         // Decrypt other passwords
  18.                         // **********************
  19.                         // **********************
  20.                         // **********************
  21.                         // **********************
  22.                         // **********************
  23.                         // Set key
  24.  
  25.  
  26.                         byte key[ CryptoPP::AES::DEFAULT_KEYLENGTH ], iv[ CryptoPP::AES::BLOCKSIZE ];
  27.                         memset( key, 0x00, CryptoPP::AES::DEFAULT_KEYLENGTH );
  28.                         memset( iv, 0x00, CryptoPP::AES::BLOCKSIZE );
  29.  
  30.  
  31.  
  32.                         // DECRYPT START~~~
  33.  
  34.                         if (ciphertext[0].size() != 0)
  35.                         {
  36.                         CryptoPP::AES::Decryption aesDecryption(key, CryptoPP::AES::DEFAULT_KEYLENGTH);
  37.                         CryptoPP::CBC_Mode_ExternalCipher::Decryption cbcDecryption( aesDecryption, iv );
  38.  
  39.                         CryptoPP::StreamTransformationFilter stfDecryptor(cbcDecryption, new CryptoPP::StringSink( qdec[0] ) );
  40.                         stfDecryptor.Put( reinterpret_cast<const unsigned char*>( ciphertext[0].c_str() ), ciphertext[0].size() );
  41.                         stfDecryptor.MessageEnd();
  42.                         QApplication::processEvents();
  43.                         }
  44.                         // **********************
  45.  
  46.  
  47.                         byte key1[ CryptoPP::AES::DEFAULT_KEYLENGTH ], iv1[ CryptoPP::AES::BLOCKSIZE ];
  48.                         memset( key1, 0x00, CryptoPP::AES::DEFAULT_KEYLENGTH );
  49.                         memset( iv1, 0x00, CryptoPP::AES::BLOCKSIZE );
  50.  
  51.  
  52.                         if (ciphertext[1].size() != 0)
  53.                         {
  54.                         CryptoPP::AES::Decryption aesDecryption1(key1, CryptoPP::AES::DEFAULT_KEYLENGTH);
  55.                         CryptoPP::CBC_Mode_ExternalCipher::Decryption cbcDecryption1( aesDecryption1, iv1 );
  56.  
  57.                         CryptoPP::StreamTransformationFilter stfDecryptor1(cbcDecryption1, new CryptoPP::StringSink( qdec[1] ) );
  58.                         stfDecryptor1.Put( reinterpret_cast<const unsigned char*>( ciphertext[1].c_str() ), ciphertext[1].size() );
  59.                         stfDecryptor1.MessageEnd();
  60.                         QApplication::processEvents();
  61.                         }
  62.  
  63.                         // **********************
  64.  
  65.  
  66.                         byte key2[ CryptoPP::AES::DEFAULT_KEYLENGTH ], iv2[ CryptoPP::AES::BLOCKSIZE ];
  67.                         memset( key2, 0x00, CryptoPP::AES::DEFAULT_KEYLENGTH );
  68.                         memset( iv2, 0x00, CryptoPP::AES::BLOCKSIZE );
  69.  
  70.  
  71.                         if (ciphertext[2].size() != 0)
  72.                         {
  73.                         CryptoPP::AES::Decryption aesDecryption2(key2, CryptoPP::AES::DEFAULT_KEYLENGTH);
  74.                         CryptoPP::CBC_Mode_ExternalCipher::Decryption cbcDecryption2( aesDecryption2, iv2 );
  75.  
  76.                         CryptoPP::StreamTransformationFilter stfDecryptor2(cbcDecryption2, new CryptoPP::StringSink( qdec[2] ) );
  77.                         stfDecryptor2.Put( reinterpret_cast<const unsigned char*>( ciphertext[2].c_str() ), ciphertext[2].size() );
  78.                         stfDecryptor2.MessageEnd();
  79.                         QApplication::processEvents();
  80.                         }
  81. ......
  82.                         // **********************
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And also, this is AES, but where do I actually set the secret key?