1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "adb/crypto/rsa_2048_key.h"
18
19 #include <android-base/logging.h>
20 #include <crypto_utils/android_pubkey.h>
21 #include <openssl/bn.h>
22 #include <openssl/rsa.h>
23
24 namespace adb {
25 namespace crypto {
26
27 namespace {
get_user_info()28 std::string get_user_info() {
29 std::string hostname;
30 if (getenv("HOSTNAME")) hostname = getenv("HOSTNAME");
31 #if !defined(_WIN32)
32 char buf[64];
33 if (hostname.empty() && gethostname(buf, sizeof(buf)) != -1) hostname = buf;
34 #endif
35 if (hostname.empty()) hostname = "unknown";
36
37 std::string username;
38 if (getenv("LOGNAME")) username = getenv("LOGNAME");
39 #if !defined(_WIN32)
40 if (username.empty() && getlogin()) username = getlogin();
41 #endif
42 if (username.empty()) hostname = "unknown";
43
44 return " " + username + "@" + hostname;
45 }
46
47 } // namespace
48
CalculatePublicKey(std::string * out,RSA * private_key)49 bool CalculatePublicKey(std::string* out, RSA* private_key) {
50 uint8_t binary_key_data[ANDROID_PUBKEY_ENCODED_SIZE];
51 if (!android_pubkey_encode(private_key, binary_key_data, sizeof(binary_key_data))) {
52 LOG(ERROR) << "Failed to convert to public key";
53 return false;
54 }
55
56 size_t expected_length;
57 if (!EVP_EncodedLength(&expected_length, sizeof(binary_key_data))) {
58 LOG(ERROR) << "Public key too large to base64 encode";
59 return false;
60 }
61
62 out->resize(expected_length);
63 size_t actual_length = EVP_EncodeBlock(reinterpret_cast<uint8_t*>(out->data()), binary_key_data,
64 sizeof(binary_key_data));
65 out->resize(actual_length);
66 out->append(get_user_info());
67 return true;
68 }
69
CreateRSA2048Key()70 std::optional<Key> CreateRSA2048Key() {
71 bssl::UniquePtr<EVP_PKEY> pkey(EVP_PKEY_new());
72 bssl::UniquePtr<BIGNUM> exponent(BN_new());
73 bssl::UniquePtr<RSA> rsa(RSA_new());
74 if (!pkey || !exponent || !rsa) {
75 LOG(ERROR) << "Failed to allocate key";
76 return std::nullopt;
77 }
78
79 BN_set_word(exponent.get(), RSA_F4);
80 RSA_generate_key_ex(rsa.get(), 2048, exponent.get(), nullptr);
81 EVP_PKEY_set1_RSA(pkey.get(), rsa.get());
82
83 return std::optional<Key>{Key(std::move(pkey), adb::proto::KeyType::RSA_2048)};
84 }
85
86 } // namespace crypto
87 } // namespace adb
88