Files
squeezelite-esp32/components/spotify/cspot/src/AuthChallenges.cpp
2023-05-06 23:50:26 +02:00

131 lines
4.9 KiB
C++

#include "AuthChallenges.h"
#include <algorithm> // for copy
#include <climits> // for CHAR_BIT
#include <random> // for default_random_engine, independent_bits_en...
#include "NanoPBHelper.h" // for pbPutString, pbEncode, pbDecode
#include "pb.h" // for pb_byte_t
#include "pb_decode.h" // for pb_release
using namespace cspot;
using random_bytes_engine =
std::independent_bits_engine<std::default_random_engine, CHAR_BIT, uint8_t>;
AuthChallenges::AuthChallenges() {
this->crypto = std::make_unique<Crypto>();
this->clientHello = {};
this->apResponse = {};
this->authRequest = {};
this->clientResPlaintext = {};
}
AuthChallenges::~AuthChallenges() {
// Destruct the protobufs
pb_release(ClientHello_fields, &clientHello);
pb_release(APResponseMessage_fields, &apResponse);
pb_release(ClientResponsePlaintext_fields, &clientResPlaintext);
pb_release(ClientResponseEncrypted_fields, &authRequest);
}
std::vector<uint8_t> AuthChallenges::prepareAuthPacket(
std::vector<uint8_t>& authData, int authType, const std::string& deviceId,
const std::string& username) {
// prepare authentication request proto
pbPutString(username, authRequest.login_credentials.username);
std::copy(authData.begin(), authData.end(),
authRequest.login_credentials.auth_data.bytes);
authRequest.login_credentials.auth_data.size = authData.size();
authRequest.login_credentials.typ = (AuthenticationType)authType;
authRequest.system_info.cpu_family = CpuFamily_CPU_UNKNOWN;
authRequest.system_info.os = Os_OS_UNKNOWN;
auto infoStr = std::string("cspot-player");
pbPutString(infoStr, authRequest.system_info.system_information_string);
pbPutString(deviceId, authRequest.system_info.device_id);
auto versionStr = std::string("cspot-1.1");
pbPutString(versionStr, authRequest.version_string);
authRequest.has_version_string = true;
return pbEncode(ClientResponseEncrypted_fields, &authRequest);
}
std::vector<uint8_t> AuthChallenges::solveApHello(
std::vector<uint8_t>& helloPacket, std::vector<uint8_t>& data) {
// Decode the response
auto skipSize = std::vector<uint8_t>(data.begin() + 4, data.end());
pb_release(APResponseMessage_fields, &apResponse);
pbDecode(apResponse, APResponseMessage_fields, skipSize);
auto diffieKey = std::vector<uint8_t>(
apResponse.challenge.login_crypto_challenge.diffie_hellman.gs,
apResponse.challenge.login_crypto_challenge.diffie_hellman.gs + 96);
// Compute the diffie hellman shared key based on the response
auto sharedKey = this->crypto->dhCalculateShared(diffieKey);
// Init client packet + Init server packets are required for the hmac challenge
data.insert(data.begin(), helloPacket.begin(), helloPacket.end());
// Solve the hmac challenge
auto resultData = std::vector<uint8_t>(0);
for (int x = 1; x < 6; x++) {
auto challengeVector = std::vector<uint8_t>(1);
challengeVector[0] = x;
challengeVector.insert(challengeVector.begin(), data.begin(), data.end());
auto digest = crypto->sha1HMAC(sharedKey, challengeVector);
resultData.insert(resultData.end(), digest.begin(), digest.end());
}
auto lastVec =
std::vector<uint8_t>(resultData.begin(), resultData.begin() + 0x14);
// Digest generated!
auto digest = crypto->sha1HMAC(lastVec, data);
clientResPlaintext.login_crypto_response.has_diffie_hellman = true;
std::copy(digest.begin(), digest.end(),
clientResPlaintext.login_crypto_response.diffie_hellman.hmac);
// Get send and receive keys
this->shanSendKey = std::vector<uint8_t>(resultData.begin() + 0x14,
resultData.begin() + 0x34);
this->shanRecvKey = std::vector<uint8_t>(resultData.begin() + 0x34,
resultData.begin() + 0x54);
return pbEncode(ClientResponsePlaintext_fields, &clientResPlaintext);
}
std::vector<uint8_t> AuthChallenges::prepareClientHello() {
// Prepare protobuf message
this->crypto->dhInit();
// Copy the public key into diffiehellman hello packet
std::copy(this->crypto->publicKey.begin(), this->crypto->publicKey.end(),
clientHello.login_crypto_hello.diffie_hellman.gc);
clientHello.login_crypto_hello.diffie_hellman.server_keys_known = 1;
clientHello.build_info.product = Product_PRODUCT_CLIENT;
clientHello.build_info.platform = Platform2_PLATFORM_LINUX_X86;
clientHello.build_info.version = SPOTIFY_VERSION;
clientHello.feature_set.autoupdate2 = true;
clientHello.cryptosuites_supported[0] = Cryptosuite_CRYPTO_SUITE_SHANNON;
clientHello.padding[0] = 0x1E;
clientHello.has_feature_set = true;
clientHello.login_crypto_hello.has_diffie_hellman = true;
clientHello.has_padding = true;
clientHello.has_feature_set = true;
// Generate the random nonce
auto nonce = crypto->generateVectorWithRandomData(16);
std::copy(nonce.begin(), nonce.end(), clientHello.client_nonce);
return pbEncode(ClientHello_fields, &clientHello);
}