Getting warning while compiling using cryptopp library

Question

I have a encrypted file using AES algorithm in CBC mode. I have key from database. I am trying to compile below code using cryptopp 5.6.2 library. It gets compiled without -Wall flag but when I enable that flag below warnings appears.

#include <iostream>
#include <fstream>
#include <exception>
#include <sstream>

#include "cryptopp/modes.h"
#include "cryptopp/aes.h"
#include "cryptopp/filters.h"
#include "cryptopp/cryptlib.h"
#include "cryptopp/hex.h"
#include "cryptopp/filters.h"
#include "cryptopp/aes.h"
#include "cryptopp/ccm.h"
#include "cryptopp/files.h"

using namespace std;
using namespace CryptoPP;

int main(int argc, char* argv[])
{
    try
    {
        byte no[16]  ;
        byte noiv[16];
        std::string out;
        std::string fileName("./encrypted.txt");
        CBC_Mode<AES>::Decryption d;
        d.SetKeyWithIV(no, sizeof(no), noiv);
        CryptoPP::FileSource(fileName.c_str(), true, new StreamTransformationFilter(d, new CryptoPP::FileSink("decrypted.txt"), CryptoPP::StreamTransformationFilter::PKCS_PADDING));
    }
    catch (CryptoPP::Exception& e)
    {
        std::cout << std::endl << e.what() << std::endl;
    }
    return 0;
}

Gets below errors on enabling -Wall flag

In file included from ./cryptopp_5.6.2/include/cryptopp/modes.h:12,
                 from poc.cpp:6:
./cryptopp_5.6.2/include/cryptopp/algparam.h: In constructor ‘CryptoPP::ConstByteArrayParameter::ConstByteArrayParameter(const T&, bool) [with T = std::basic_string<char, std::char_traits<char>, std::allocator<char> >]’:
./cryptopp_5.6.2/include/cryptopp/filters.h:793:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:26: warning: unused variable ‘cryptopp_assert_26’
In file included from ./cryptopp_5.6.2/include/cryptopp/modes.h:12,
                 from poc.cpp:6:
./cryptopp_5.6.2/include/cryptopp/algparam.h: In member function ‘void CryptoPP::AlgorithmParametersTemplate<T>::MoveInto(void*) const [with T = std::ostream*]’:
poc.cpp:36:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’
./cryptopp_5.6.2/include/cryptopp/algparam.h: In member function ‘void CryptoPP::AlgorithmParametersTemplate<T>::MoveInto(void*) const [with T = const wchar_t*]’:
poc.cpp:36:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’
./cryptopp_5.6.2/include/cryptopp/algparam.h: In member function ‘void CryptoPP::AlgorithmParametersTemplate<T>::MoveInto(void*) const [with T = const char*]’:
poc.cpp:36:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’
./cryptopp_5.6.2/include/cryptopp/algparam.h: In member function ‘void CryptoPP::AlgorithmParametersTemplate<T>::MoveInto(void*) const [with T = std::istream*]’:
poc.cpp:36:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’
./cryptopp_5.6.2/include/cryptopp/algparam.h: In member function ‘void CryptoPP::AlgorithmParametersTemplate<T>::MoveInto(void*) const [with T = const int*]’:
poc.cpp:36:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’
./cryptopp_5.6.2/include/cryptopp/algparam.h: In member function ‘void CryptoPP::AlgorithmParametersTemplate<T>::MoveInto(void*) const [with T = unsigned char]’:
poc.cpp:36:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’
./cryptopp_5.6.2/include/cryptopp/algparam.h: In member function ‘void CryptoPP::AlgorithmParametersTemplate<T>::MoveInto(void*) const [with T = const byte*]’:
poc.cpp:36:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’
./cryptopp_5.6.2/include/cryptopp/algparam.h: In member function ‘void CryptoPP::AlgorithmParametersTemplate<T>::MoveInto(void*) const [with T = CryptoPP::RandomNumberGenerator*]’:
poc.cpp:36:   instantiated from here
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’
./cryptopp_5.6.2/include/cryptopp/misc.h: At global scope:
./cryptopp_5.6.2/include/cryptopp/misc.h:548: warning: ‘std::string CryptoPP::StringNarrow(const wchar_t*, bool)’ defined but not used

`p` isn't used, nothing you can do about and most of all since it's a library issue you shouldn't care. Moreover, I'm pretty sure it has no impact — Hatted Rooster, Sep 29 '16 at 12:28
If you want to suppress those warnings for library headers check here: http://stackoverflow.com/questions/1867065/how-to-suppress-gcc-warnings-from-library-headers — Hayt, Sep 29 '16 at 12:31

jww · Answer 1 · 2016-09-30T18:05:18.757

below code using cryptopp 5.6.2 library...

5.6.2 is kind of old. We are getting ready to release Crypto++ 5.6.5.

It gets compiled without -Wall flag but when I enable that flag below warnings appears.
./cryptopp_5.6.2/include/cryptopp/algparam.h:322: warning: unused variable ‘p’

The warning was cleared about 18 months ago. It was first seen in a release at Crypto++ 5.6.3. Also see Commit 5f25c736: Add CRYPTOPP_UNUSED to help supress unused variable warnings.

Gets below errors on enabling -Wall flag ...

Crypto++ is now clean at -Wall -Wextra under GCC and compatibles. Its also clean under MSC with /W4. Finally, its clean under Solaris' SunCC.

If interested, here is the release process and security gates we are required to pass through for a release (from Release Process | Analysis Tools):

Compiler Warnings
Clang and GCC Sanitizers
Valgrind
Enterprise Analysis
Coverity

Right now, Coverity is holding-up 5.6.5. We recently expanded Coverity coverage to Linux, Unix, OS X, and Windows (previously it was Linux only). Coverity is producing findings and we are working through them.

Getting warning while compiling using cryptopp library

1 Answers1