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[TAS-116] tag verification for ADKD=0

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This commit is contained in:
Cesare G. Martínez 2024-01-08 19:11:13 +01:00
parent fdbd99ce6b
commit f7d7f5a784
3 changed files with 97 additions and 10 deletions
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103
src/core/libs/osnma_msg_receiver.cc
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@ -460,7 +460,7 @@ void osnma_msg_receiver::read_mack_block(const std::shared_ptr<OSNMA_msg>& osnma
}
// compute time of subrame and kroot time of applicability, used in read_mack_body and process_mack_message
// TODO - find a better placement
d_GST_SIS = osnma_msg->TOW_sf0 + osnma_msg->WN_sf0 * 604800;
d_GST_SIS = osnma_msg->TOW_sf0 + osnma_msg->WN_sf0 * 604800; // TODO - unsure about this operation and of the -24 seconds,...
d_GST_0 = d_osnma_data.d_dsm_kroot_message.towh_k + 604800 * d_osnma_data.d_dsm_kroot_message.wn_k;
d_GST_Sf = d_GST_0 + 30 * std::floor((d_GST_SIS-d_GST_0)/30); // Eq. 3 R.G.
if (d_osnma_data.d_dsm_kroot_message.ts != 0) // C: 4 ts < ts < 10
@ -888,7 +888,6 @@ void osnma_msg_receiver::process_mack_message(const std::shared_ptr<OSNMA_msg>&
{
mac = d_crypto->computeCMAC_AES(applicable_key, m);
}
// Truncate the twelve MSBits and compare with received MACSEQ
uint16_t mac_msb = 0;
if (!mac.empty())
@ -899,17 +898,101 @@ void osnma_msg_receiver::process_mack_message(const std::shared_ptr<OSNMA_msg>&
int num_tags_added = 0;
if (computed_macseq == d_osnma_data.d_mack_message.header.macseq)
{
// C: TODO - for each tag in tag_and_info[] && until l_t_verified <= L_t_min or tags of MACK are finished
// C: d_osnma_data.d_dsm_kroot_message.ts gives l_t of each tag for this mack
// C: tag = trunc(l_t, mac(applicable_key,m))
// C: where m = (PRNd || PRNa || GSTsf || CTR || NMAS || NavData || P)
// C: si l_t_verified >= L_t_min d_new_data = true
std::cout << "OSNMA: MACSEQ authenticated for PRN_A "
<< osnma_msg->PRN << " with WN="
<< osnma_msg->WN_sf0 << ", TOW="
<< osnma_msg->TOW_sf0 << ". Tags added: "
<< num_tags_added << std::endl;
<< osnma_msg->TOW_sf0 << ". Verifying tags. "
<< std::endl;
uint8_t l_t_verified = 0; // tag bits verified
uint8_t i = 0;
// TODO - configuration file must define which tags shall be verified
// e.g. NavDataVerification: A == ALL, T == Timing Parameters, ECS == Ephemeris,Clock and Status.
std::string navDataToVerify = "EphemerisClockAndStatus"; // ADKD 0
// Timing Parameters ADKD 4
// EphemerisClockAndStatus ADKD 12 10+ Delay
m.clear();
uint8_t lt_bits = 0;
const auto it2 = OSNMA_TABLE_11.find(d_osnma_data.d_dsm_kroot_message.ts);
if (it2 != OSNMA_TABLE_11.cend())
{
lt_bits = it2->second;
}
if (lt_bits == 0)
{
return; // C: TODO if Tag length is 0, what is the action? no verification possible of NavData for sure.
}
while (i < d_osnma_data.d_mack_message.tag_and_info.size() && l_t_verified < d_Lt_min)
{
// compute m
m.push_back(d_osnma_data.d_mack_message.tag_and_info[i].tag_info.PRN_d);
m.push_back(osnma_msg->PRN);
m.push_back(static_cast<uint8_t>((d_GST_Sf & 0xFF000000) >> 24));
m.push_back(static_cast<uint8_t>((d_GST_Sf & 0x00FF0000) >> 16));
m.push_back(static_cast<uint8_t>((d_GST_Sf & 0x0000FF00) >> 8));
m.push_back(static_cast<uint8_t>(d_GST_Sf & 0x000000FF));
m.push_back(i+1); // CTRauto
m.push_back(d_osnma_data.d_nma_header.nmas);
// TODO - other ADKD need different data.
// TODO - store buffer the NavData of 11 last subframes, ADKD 0 and 12 => NavData belongs to SF-1
m.insert(m.end(),osnma_msg->EphemerisClockAndStatusData.begin(),osnma_msg->EphemerisClockAndStatusData.end()) ;
i = 0;
while (i<10/*TODO - number of padding zeroes to be computed*/)
{
m.push_back(0);
i++;
}
// compute mac
if (d_osnma_data.d_dsm_kroot_message.mf == 0) // C: HMAC-SHA-256
{
mac = d_crypto->computeHMAC_SHA_256(applicable_key, m);
}
else if (d_osnma_data.d_dsm_kroot_message.mf == 1) // C: CMAC-AES
{
mac = d_crypto->computeCMAC_AES(applicable_key, m);
}
// compute tag = trunc(l_t, mac(K,m)) Eq. 23 ICD
uint64_t computed_mac = static_cast<uint64_t>(mac[0]) << (lt_bits - 8);
computed_mac += (static_cast<uint64_t>(mac[1]) << (lt_bits - 16));
if (lt_bits == 20)
{
computed_mac += (static_cast<uint64_t>(mac[1] & 0xF0) >> 4);
}
else if (lt_bits == 24)
{
computed_mac += static_cast<uint64_t>(mac[2]);
}
else if (lt_bits == 28)
{
computed_mac += (static_cast<uint64_t>(mac[2]) << 4);
computed_mac += (static_cast<uint64_t>(mac[3] & 0xF0) >> 4);
}
else if (lt_bits == 32)
{
computed_mac += (static_cast<uint64_t>(mac[2]) << 8);
computed_mac += static_cast<uint64_t>(mac[3]);
}
else if (lt_bits == 40)
{
computed_mac += (static_cast<uint64_t>(mac[2]) << 16);
computed_mac += (static_cast<uint64_t>(mac[3]) << 8);
computed_mac += static_cast<uint64_t>(mac[4]);
}
// Compare computed tag with received one truncated
if (d_osnma_data.d_mack_message.tag_and_info[i].tag == computed_mac)
{
std::cout << "Galileo OSNMA: Tag verification successful " << std::endl;
l_t_verified += lt_bits;
}
else
{
std::cout << "Galileo OSNMA: Tag verification failed " << std::endl;
}
}
}
}

1
src/core/libs/osnma_msg_receiver.h
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@ -85,6 +85,7 @@ private:
bool d_public_key_verified{false};
bool d_kroot_verified{false};
uint32_t d_GST_Sf {}; // C: used for MACSEQ and Tesla Key verification
uint8_t d_Lt_min {}; // minimum equivalent tag length
uint32_t d_GST_0 {};
uint32_t d_GST_SIS {};
};

3
src/core/system_parameters/galileo_inav_message.h
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@ -49,6 +49,9 @@ public:
uint32_t PRN{};
uint32_t WN_sf0{};
uint32_t TOW_sf0{};
// TODO - NavData to be retrieved correctly
std::vector<uint8_t> EphemerisClockAndStatusData {};
std::vector<uint8_t> TimingData {};
uint32_t t0e_1{};
uint32_t IOD_nav{};
};