When building on macosx 10.4.1 / gcc 4.0.0: Here is command and error:
c++ -O2 -DNDEBUG -ffunction-sections -fdata-sections -pipe -D__pic__ -c esign.cpp esign.cpp: In member function `virtual void CryptoPP::InvertibleESIGNFunction::GenerateRandom(CryptoPP::RandomNumberGenerator&, const CryptoPP::NameValuePairs&)': esign.cpp:97: error: cannot allocate an object of abstract type 'CryptoPP::NameValuePairs' cryptlib.h:222: note: because the following virtual functions are pure within 'CryptoPP::NameValuePairs': cryptlib.h:303: note: virtual bool CryptoPP::NameValuePairs::GetVoidValue(const char*, const std::type_info&, void*) const
make: *** [esign.o] Error 1
