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#include <openssl/hmac.h>
#include <openssl/sha.h>
#include "integrity_algo.hpp"
#include "message_parsers.hpp"
namespace cipher
{
namespace integrity
{
Interface::Interface(const Buffer& sik, const Key& addKey, size_t authLength)
{
unsigned int mdLen = 0;
// Generated K1 for the integrity algorithm with the additional key keyed
// with SIK.
if (HMAC(EVP_sha1(), sik.data(), sik.size(), addKey.data(),
addKey.size(), K1.data(), &mdLen) == NULL)
{
throw std::runtime_error("Generating Key1 for integrity "
"algorithm failed");
}
authCodeLength = authLength;
}
Buffer AlgoSHA1::generateHMAC(const uint8_t* input, const size_t len) const
{
Buffer output(SHA_DIGEST_LENGTH);
unsigned int mdLen = 0;
if (HMAC(EVP_sha1(), K1.data(), K1.size(), input, len,
output.data(), &mdLen) == NULL)
{
throw std::runtime_error("Generating integrity data failed");
}
// HMAC generates Message Digest to the size of SHA_DIGEST_LENGTH, the
// AuthCode field length is based on the integrity algorithm. So we are
// interested only in the AuthCode field length of the generated Message
// digest.
output.resize(authCodeLength);
return output;
}
bool AlgoSHA1::verifyIntegrityData(const Buffer& packet,
const size_t length,
Buffer::const_iterator integrityData) const
{
auto output = generateHMAC(
packet.data() + message::parser::RMCP_SESSION_HEADER_SIZE,
length);
// Verify if the generated integrity data for the packet and the received
// integrity data matches.
return (std::equal(output.begin(), output.end(), integrityData));
}
Buffer AlgoSHA1::generateIntegrityData(const Buffer& packet) const
{
return generateHMAC(
packet.data() + message::parser::RMCP_SESSION_HEADER_SIZE,
packet.size() - message::parser::RMCP_SESSION_HEADER_SIZE);
}
}// namespace integrity
}// namespace cipher
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