128 lines
3.4 KiB
C++
128 lines
3.4 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#include "td/mtproto/RSA.h"
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#include "td/mtproto/mtproto_api.h"
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#include "td/utils/as.h"
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#include "td/utils/common.h"
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#include "td/utils/crypto.h"
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#include "td/utils/misc.h"
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#include "td/utils/Random.h"
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#include "td/utils/ScopeGuard.h"
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#include "td/utils/Slice.h"
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#include "td/utils/Status.h"
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#include "td/utils/tl_storers.h"
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#include <openssl/bio.h>
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#include <openssl/bn.h>
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#include <openssl/pem.h>
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#include <openssl/rsa.h>
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namespace td {
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RSA::RSA(BigNum n, BigNum e) : n_(std::move(n)), e_(std::move(e)) {
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}
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RSA RSA::clone() const {
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return RSA(n_.clone(), e_.clone());
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}
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Result<RSA> RSA::from_pem_public_key(Slice pem) {
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init_crypto();
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auto *bio =
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BIO_new_mem_buf(const_cast<void *>(static_cast<const void *>(pem.ubegin())), narrow_cast<int32>(pem.size()));
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if (bio == nullptr) {
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return Status::Error("Cannot create BIO");
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}
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SCOPE_EXIT {
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BIO_free(bio);
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};
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auto rsa = PEM_read_bio_RSAPublicKey(bio, nullptr, nullptr, nullptr);
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if (rsa == nullptr) {
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return Status::Error("Error while reading rsa pubkey");
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}
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SCOPE_EXIT {
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RSA_free(rsa);
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};
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if (RSA_size(rsa) != 256) {
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return Status::Error("RSA_size != 256");
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}
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const BIGNUM *n_num;
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const BIGNUM *e_num;
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#if OPENSSL_VERSION_NUMBER < 0x10100000L
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n_num = rsa->n;
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e_num = rsa->e;
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#else
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RSA_get0_key(rsa, &n_num, &e_num, nullptr);
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#endif
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auto n = static_cast<void *>(BN_dup(n_num));
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auto e = static_cast<void *>(BN_dup(e_num));
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if (n == nullptr || e == nullptr) {
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return Status::Error("Cannot dup BIGNUM");
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}
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return RSA(BigNum::from_raw(n), BigNum::from_raw(e));
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}
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int64 RSA::get_fingerprint() const {
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// string objects are necessary, because mtproto_api::rsa_public_key contains Slice inside
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string n_str = n_.to_binary();
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string e_str = e_.to_binary();
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mtproto_api::rsa_public_key public_key(n_str, e_str);
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size_t size = tl_calc_length(public_key);
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std::vector<unsigned char> tmp(size);
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size = tl_store_unsafe(public_key, tmp.data());
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CHECK(size == tmp.size());
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unsigned char key_sha1[20];
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sha1(Slice(tmp.data(), tmp.size()), key_sha1);
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return as<int64>(key_sha1 + 12);
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}
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size_t RSA::size() const {
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// Checked in RSA::from_pem_public_key step
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return 256;
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}
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size_t RSA::encrypt(unsigned char *from, size_t from_len, size_t max_from_len, unsigned char *to, size_t to_len) const {
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CHECK(from_len > 0 && from_len <= 2550);
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size_t pad = (25500 - from_len - 32) % 255 + 32;
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size_t chunks = (from_len + pad) / 255;
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int bits = n_.get_num_bits();
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CHECK(bits >= 2041 && bits <= 2048);
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CHECK(chunks * 255 == from_len + pad);
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CHECK(from_len + pad <= max_from_len);
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CHECK(chunks * 256 <= to_len);
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Random::secure_bytes(from + from_len, pad);
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BigNumContext ctx;
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BigNum y;
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while (chunks-- > 0) {
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BigNum x = BigNum::from_binary(Slice(from, 255));
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BigNum::mod_exp(y, x, e_, n_, ctx);
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MutableSlice(to, 256).copy_from(y.to_binary(256));
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to += 256;
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}
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return chunks * 256;
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}
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void RSA::decrypt_signature(Slice from, MutableSlice to) const {
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CHECK(from.size() == 256);
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BigNumContext ctx;
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BigNum x = BigNum::from_binary(from);
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BigNum y;
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BigNum::mod_exp(y, x, e_, n_, ctx);
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to.copy_from(y.to_binary(256));
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}
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} // namespace td
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