Well, I tried code available on http://www.cryptopp.com/wiki/VMAC in my NS-3 project on the following way: inputString = base64_encode (inputString); byte* Kkey = key->GetKey(); byte digestBytes[key->GetSize()]; byte digestBytes2[key->GetSize()]; CryptoPP::VMAC vmac; vmac.SetKeyWithIV(Kkey, key->GetSize(), m_iv, CryptoPP::AES::BLOCKSIZE); vmac.CalculateDigest(digestBytes, (byte *) inputString.c_str(), inputString.length()); //VMAC Verification vmac.SetKeyWithIV(Kkey, key->GetSize(), m_iv, CryptoPP::AES::BLOCKSIZE); vmac.CalculateDigest(digestBytes2, (byte *) inputString.c_str(), inputString.length()); std::string outputString = std::string( (char*)digestBytes, sizeof(digestBytes […]