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| // | |
| // Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2026 | |
| // | |
| // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
| // | |
| class BasicHandshake { | |
| public: | |
| struct KeyPair { | |
| td::SecureString private_key; | |
| td::SecureString public_key; | |
| }; | |
| static td::Result<KeyPair> generate_key_pair() { | |
| EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(NID_X25519, nullptr); | |
| if (pctx == nullptr) { | |
| return td::Status::Error("Can't create EXP_PKEY_CTX"); | |
| } | |
| SCOPE_EXIT { | |
| EVP_PKEY_CTX_free(pctx); | |
| }; | |
| if (EVP_PKEY_keygen_init(pctx) <= 0) { | |
| return td::Status::Error("Can't init keygen"); | |
| } | |
| EVP_PKEY *pkey = nullptr; | |
| if (EVP_PKEY_keygen(pctx, &pkey) <= 0) { | |
| return td::Status::Error("Can't generate key"); | |
| } | |
| TRY_RESULT(private_key, X25519_key_from_PKEY(pkey, true)); | |
| TRY_RESULT(public_key, X25519_key_from_PKEY(pkey, false)); | |
| KeyPair res; | |
| res.private_key = std::move(private_key); | |
| res.public_key = std::move(public_key); | |
| return std::move(res); | |
| } | |
| static td::SecureString expand_secret(td::Slice secret) { | |
| td::SecureString res(128); | |
| td::hmac_sha512(secret, "0", res.as_mutable_slice().substr(0, 64)); | |
| td::hmac_sha512(secret, "1", res.as_mutable_slice().substr(64, 64)); | |
| return res; | |
| } | |
| static td::Result<td::SecureString> privateKeyToPem(td::Slice key) { | |
| auto pkey_private = EVP_PKEY_new_raw_private_key(EVP_PKEY_X25519, nullptr, key.ubegin(), 32); | |
| CHECK(pkey_private != nullptr); | |
| auto res = X25519_pem_from_PKEY(pkey_private, true); | |
| EVP_PKEY_free(pkey_private); | |
| return res; | |
| } | |
| static td::Result<td::SecureString> calc_shared_secret(td::Slice private_key, td::Slice other_public_key) { | |
| auto pkey_private = EVP_PKEY_new_raw_private_key(EVP_PKEY_X25519, nullptr, private_key.ubegin(), 32); | |
| if (pkey_private == nullptr) { | |
| return td::Status::Error("Invalid X25519 private key"); | |
| } | |
| SCOPE_EXIT { | |
| EVP_PKEY_free(pkey_private); | |
| }; | |
| auto pkey_public = | |
| EVP_PKEY_new_raw_public_key(EVP_PKEY_X25519, nullptr, other_public_key.ubegin(), other_public_key.size()); | |
| if (pkey_public == nullptr) { | |
| return td::Status::Error("Invalid X25519 public key"); | |
| } | |
| SCOPE_EXIT { | |
| EVP_PKEY_free(pkey_public); | |
| }; | |
| EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new(pkey_private, nullptr); | |
| if (ctx == nullptr) { | |
| return td::Status::Error("Can't create EVP_PKEY_CTX"); | |
| } | |
| SCOPE_EXIT { | |
| EVP_PKEY_CTX_free(ctx); | |
| }; | |
| if (EVP_PKEY_derive_init(ctx) <= 0) { | |
| return td::Status::Error("Can't init derive"); | |
| } | |
| if (EVP_PKEY_derive_set_peer(ctx, pkey_public) <= 0) { | |
| return td::Status::Error("Can't init derive"); | |
| } | |
| size_t result_len = 0; | |
| if (EVP_PKEY_derive(ctx, nullptr, &result_len) <= 0) { | |
| return td::Status::Error("Can't get result length"); | |
| } | |
| if (result_len != 32) { | |
| return td::Status::Error("Unexpected result length"); | |
| } | |
| td::SecureString result(result_len, '\0'); | |
| if (EVP_PKEY_derive(ctx, result.as_mutable_slice().ubegin(), &result_len) <= 0) { | |
| return td::Status::Error("Failed to compute shared secret"); | |
| } | |
| return std::move(result); | |
| } | |
| static td::Result<td::SecureString> get_public_key(td::Slice private_key) { | |
| auto pkey_private = EVP_PKEY_new_raw_private_key(EVP_PKEY_X25519, nullptr, private_key.ubegin(), 32); | |
| if (pkey_private == nullptr) { | |
| return td::Status::Error("Invalid X25519 private key"); | |
| } | |
| SCOPE_EXIT { | |
| EVP_PKEY_free(pkey_private); | |
| }; | |
| auto func = &EVP_PKEY_get_raw_public_key; | |
| size_t len = 0; | |
| if (func(pkey_private, nullptr, &len) == 0) { | |
| return td::Status::Error("Failed to get raw key length"); | |
| } | |
| CHECK(len == 32); | |
| td::SecureString result(len); | |
| if (func(pkey_private, result.as_mutable_slice().ubegin(), &len) == 0) { | |
| return td::Status::Error("Failed to get raw key"); | |
| } | |
| return std::move(result); | |
| } | |
| private: | |
| static td::Result<td::SecureString> X25519_key_from_PKEY(EVP_PKEY *pkey, bool is_private) { | |
| auto func = is_private ? &EVP_PKEY_get_raw_private_key : &EVP_PKEY_get_raw_public_key; | |
| size_t len = 0; | |
| if (func(pkey, nullptr, &len) == 0) { | |
| return td::Status::Error("Failed to get raw key length"); | |
| } | |
| CHECK(len == 32); | |
| td::SecureString result(len); | |
| if (func(pkey, result.as_mutable_slice().ubegin(), &len) == 0) { | |
| return td::Status::Error("Failed to get raw key"); | |
| } | |
| return std::move(result); | |
| } | |
| static td::Result<td::SecureString> X25519_pem_from_PKEY(EVP_PKEY *pkey, bool is_private) { | |
| BIO *mem_bio = BIO_new(BIO_s_mem()); | |
| SCOPE_EXIT { | |
| BIO_vfree(mem_bio); | |
| }; | |
| if (is_private) { | |
| PEM_write_bio_PrivateKey(mem_bio, pkey, nullptr, nullptr, 0, nullptr, nullptr); | |
| } else { | |
| PEM_write_bio_PUBKEY(mem_bio, pkey); | |
| } | |
| char *data_ptr = nullptr; | |
| auto data_size = BIO_get_mem_data(mem_bio, &data_ptr); | |
| return td::SecureString(data_ptr, data_size); | |
| } | |
| }; | |
| struct BasicHandshakeTest { | |
| BasicHandshake::KeyPair alice; | |
| BasicHandshake::KeyPair bob; | |
| td::SecureString shared_secret; | |
| td::SecureString key; | |
| }; | |
| static void KDF3(td::Slice auth_key, const td::UInt128 &msg_key, int X, td::UInt256 *aes_key, td::UInt128 *aes_iv) { | |
| td::uint8 buf_raw[36 + 16]; | |
| td::MutableSlice buf(buf_raw, 36 + 16); | |
| td::Slice msg_key_slice = td::as_slice(msg_key); | |
| // sha256_a = SHA256 (msg_key + substr(auth_key, x, 36)); | |
| buf.copy_from(msg_key_slice); | |
| buf.substr(16, 36).copy_from(auth_key.substr(X, 36)); | |
| td::uint8 sha256_a_raw[32]; | |
| td::MutableSlice sha256_a(sha256_a_raw, 32); | |
| sha256(buf, sha256_a); | |
| // sha256_b = SHA256 (substr(auth_key, 40+x, 36) + msg_key); | |
| buf.copy_from(auth_key.substr(40 + X, 36)); | |
| buf.substr(36).copy_from(msg_key_slice); | |
| td::uint8 sha256_b_raw[32]; | |
| td::MutableSlice sha256_b(sha256_b_raw, 32); | |
| sha256(buf, sha256_b); | |
| // aes_key = substr(sha256_a, 0, 8) + substr(sha256_b, 8, 16) + substr(sha256_a, 24, 8); | |
| td::MutableSlice aes_key_slice(aes_key->raw, sizeof(aes_key->raw)); | |
| aes_key_slice.copy_from(sha256_a.substr(0, 8)); | |
| aes_key_slice.substr(8).copy_from(sha256_b.substr(8, 16)); | |
| aes_key_slice.substr(24).copy_from(sha256_a.substr(24, 8)); | |
| // aes_iv = substr(sha256_b, 0, 4) + substr(sha256_a, 8, 8) + substr(sha256_b, 24, 4); | |
| td::MutableSlice aes_iv_slice(aes_iv->raw, sizeof(aes_iv->raw)); | |
| aes_iv_slice.copy_from(sha256_b.substr(0, 4)); | |
| aes_iv_slice.substr(4).copy_from(sha256_a.substr(8, 8)); | |
| aes_iv_slice.substr(12).copy_from(sha256_b.substr(24, 4)); | |
| } | |
| static td::SecureString encrypt(td::Slice key, td::Slice data, td::int32 seqno, int X) { | |
| td::SecureString res(data.size() + 4 + 16); | |
| res.as_mutable_slice().substr(20).copy_from(data); | |
| // big endian | |
| td::uint8 *ptr = res.as_mutable_slice().substr(16).ubegin(); | |
| ptr[0] = static_cast<td::uint8>((seqno >> 24) & 255); | |
| ptr[1] = static_cast<td::uint8>((seqno >> 16) & 255); | |
| ptr[2] = static_cast<td::uint8>((seqno >> 8) & 255); | |
| ptr[3] = static_cast<td::uint8>(seqno & 255); | |
| td::mtproto::AuthKey auth_key(0, key.str()); | |
| auto payload = res.as_mutable_slice().substr(16); | |
| td::UInt128 msg_key = td::mtproto::Transport::calc_message_key2(auth_key, X, payload).second; | |
| td::UInt256 aes_key; | |
| td::UInt128 aes_iv; | |
| KDF3(key, msg_key, X, &aes_key, &aes_iv); | |
| td::AesCtrState aes; | |
| aes.init(aes_key.as_slice(), aes_iv.as_slice()); | |
| aes.encrypt(payload, payload); | |
| res.as_mutable_slice().copy_from(msg_key.as_slice()); | |
| return res; | |
| } | |
| static BasicHandshakeTest gen_test() { | |
| BasicHandshakeTest res; | |
| res.alice = BasicHandshake::generate_key_pair().move_as_ok(); | |
| res.bob = BasicHandshake::generate_key_pair().move_as_ok(); | |
| res.shared_secret = BasicHandshake::calc_shared_secret(res.alice.private_key, res.bob.public_key).move_as_ok(); | |
| res.key = BasicHandshake::expand_secret(res.shared_secret); | |
| return res; | |
| } | |
| static void run_test(const BasicHandshakeTest &test) { | |
| CHECK(BasicHandshake::get_public_key(test.alice.private_key).move_as_ok() == test.alice.public_key); | |
| CHECK(BasicHandshake::get_public_key(test.bob.private_key).move_as_ok() == test.bob.public_key); | |
| auto alice_secret = BasicHandshake::calc_shared_secret(test.alice.private_key, test.bob.public_key).move_as_ok(); | |
| auto bob_secret = BasicHandshake::calc_shared_secret(test.bob.private_key, test.alice.public_key).move_as_ok(); | |
| auto key = BasicHandshake::expand_secret(alice_secret); | |
| CHECK(alice_secret == bob_secret); | |
| CHECK(alice_secret == test.shared_secret); | |
| LOG(ERROR) << "Key\n\t" << td::base64url_encode(key) << "\n"; | |
| CHECK(key == test.key); | |
| } | |
| static td::StringBuilder &operator<<(td::StringBuilder &sb, const BasicHandshake::KeyPair &key_pair) { | |
| sb << "\tpublic_key (base64url) = " << td::base64url_encode(key_pair.public_key) << "\n"; | |
| sb << "\tprivate_key (base64url) = " << td::base64url_encode(key_pair.private_key) << "\n"; | |
| sb << "\tprivate_key (pem) = \n" << BasicHandshake::privateKeyToPem(key_pair.private_key).ok() << "\n"; | |
| return sb; | |
| } | |
| static td::StringBuilder &operator<<(td::StringBuilder &sb, const BasicHandshakeTest &test) { | |
| sb << "Alice\n" << test.alice; | |
| sb << "Bob\n" << test.bob; | |
| sb << "SharedSecret\n\t" << td::base64url_encode(test.shared_secret) << "\n"; | |
| sb << "Key\n\t" << td::base64url_encode(test.key) << "\n"; | |
| std::string data = "hello world"; | |
| sb << "encrypt(\"" << data << "\", X=0) = \n\t" << td::base64url_encode(encrypt(test.key, data, 1, 0)) << "\n"; | |
| sb << "encrypt(\"" << data << "\", X=8) = \n\t" << td::base64url_encode(encrypt(test.key, data, 1, 8)) << "\n"; | |
| return sb; | |
| } | |
| static BasicHandshakeTest pregenerated_test() { | |
| BasicHandshakeTest test; | |
| test.alice.public_key = td::base64url_decode_secure("QlCME5fXLyyQQWeYnBiGAZbmzuD4ayOuADCFgmioOBY").move_as_ok(); | |
| test.alice.private_key = td::base64url_decode_secure("8NZGWKfRCJfiks74RG9_xHmYydarLiRsoq8VcJGPglg").move_as_ok(); | |
| test.bob.public_key = td::base64url_decode_secure("I1yzfmMCZzlI7xwMj1FJ3O3I3_aEUtv6CxbHiDGzr18").move_as_ok(); | |
| test.bob.private_key = td::base64url_decode_secure("YMGoowtnZ99roUM2y5JRwiQrwGaNJ-ZRE5boy-l4aHg").move_as_ok(); | |
| test.shared_secret = td::base64url_decode_secure("0IIvKJuXEwmAp41fYhjUnWqLTYQJ7QeKZKYuCG8mFz8").move_as_ok(); | |
| test.key = td::base64url_decode_secure( | |
| "JHmD-XW9j-13G6KP0tArIhQNDRVbRkKxx0MG0pa2nOgwJHNfiggM0I0RiNIr23-1wRboRtan4WvqOHsxAt_cngYX15_" | |
| "HYe8tJdEwHcmlnXq7LtprigzExaNJS7skfOo2irClj-7EL06-jMrhfwngSJFsak8JFSw8s6R4fwCsr50") | |
| .move_as_ok(); | |
| return test; | |
| } | |
| int main() { | |
| td::detail::ThreadIdGuard thread_id_guard; | |
| auto test = gen_test(); | |
| run_test(test); | |
| run_test(pregenerated_test()); | |
| LOG(ERROR) << "\n" << pregenerated_test(); | |
| } | |
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