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Thread: Cryptopp Help

  1. 15th March 2013, 10:00 #1
    ttimt
    ttimt is offline Novice
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    Default Cryptopp Help

    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?
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  2. 17th March 2013, 04:50 #2
    ttimt
    ttimt is offline Novice
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    Default Re: Cryptopp Help

    I found out that this error occurs is related to the plain text inserted. And now I guess is because of some unicode while reading. I ran gdb and check the cipher size and found out that 1 of them is 14 byte instead of 16 and when I print it out it shows only 3/4 of the cipher. The input file is 16 byte. So it seems I need to try to read unicode from file. But how to read?
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