Files
U2FDevice/U2F_Register_APDU.cpp

101 lines
2.9 KiB
C++

#include "U2F_Register_APDU.hpp"
#include <exception>
#include <cstring>
#include "micro-ecc/uECC.h"
#include "Certificates.hpp"
#include <mbedtls/sha256.h>
#include <iostream>
#include "APDU.hpp"
#include "U2FMessage.hpp"
#include "u2f.hpp"
#include "Signature.hpp"
using namespace std;
U2F_Register_APDU::U2F_Register_APDU(const U2F_Msg_CMD &msg, const vector<uint8_t> &data)
: U2F_Msg_CMD{ msg }
{
if (data.size() != 64)
{
//Incorrect registration size
throw APDU_STATUS::SW_WRONG_LENGTH;
}
else if (p1 != 0x00 || p2 != 0x00)
{
//Invalid U2F Message (APDU) parameters detected
throw APDU_STATUS::SW_COMMAND_NOT_ALLOWED;
}
copy(data.data() + 0, data.data() + 32, challengeP.begin());
copy(data.data() + 32, data.data() + 64, appP.begin());
//Use crypto lib to generate keypair
Storage::PrivKey privKey{};
Storage::PubKey pubKey{};
//First byte must be 0x04 for some reason
pubKey[0] = 0x04;
uECC_make_key(pubKey.data() + 1, privKey.data(), uECC_secp256r1());
this->keyH = Storage::appParams.size(); //To increment the key handle
Storage::appParams[this->keyH] = appP;
Storage::privKeys[this->keyH] = privKey;
Storage::pubKeys[this->keyH] = pubKey;
Storage::keyCounts[this->keyH] = 0;
}
void U2F_Register_APDU::respond(const uint32_t channelID) const
{
U2FMessage m{};
m.cid = channelID;
m.cmd = U2FHID_MSG;
auto& response = m.data;
const auto appParam = Storage::appParams[this->keyH];
const auto pubKey = Storage::pubKeys[this->keyH];
response.push_back(0x05);
copy(pubKey.begin(), pubKey.end(), back_inserter(response));
response.push_back(sizeof(this->keyH));
auto fakeKeyHBytes = reinterpret_cast<const uint8_t *>(&this->keyH);
copy(fakeKeyHBytes, fakeKeyHBytes + sizeof(this->keyH), back_inserter(response));
copy(attestCert, end(attestCert), back_inserter(response));
//Gen signature
Digest digest;
{
mbedtls_sha256_context shaContext;
mbedtls_sha256_init(&shaContext);
mbedtls_sha256_starts(&shaContext, 0);
uint8_t byteReserved = 0;
mbedtls_sha256_update(&shaContext, reinterpret_cast<unsigned char*>(&byteReserved), 1);
mbedtls_sha256_update(&shaContext, reinterpret_cast<const unsigned char*>(appParam.data()), appParam.size());
mbedtls_sha256_update(&shaContext, reinterpret_cast<const unsigned char*>(challengeP.data()), challengeP.size());
mbedtls_sha256_update(&shaContext, reinterpret_cast<const unsigned char*>(&keyH), sizeof(keyH));
mbedtls_sha256_update(&shaContext, reinterpret_cast<const unsigned char*>(pubKey.data()), pubKey.size());
mbedtls_sha256_finish(&shaContext, digest.data());
mbedtls_sha256_free(&shaContext);
}
Signature signature;
uECC_sign(attestPrivKey, digest.data(), digest.size(), signature.data(), uECC_secp256r1());
//Append signature as DER
appendSignatureAsDER(response, signature);
response.push_back(static_cast<uint16_t>(APDU_STATUS::SW_NO_ERROR) >> 8);
response.push_back(static_cast<uint16_t>(APDU_STATUS::SW_NO_ERROR) & 0xff);
m.write();
}