1 /*
2  * Copyright 2015 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 <keymaster/km_openssl/openssl_utils.h>
18 
19 #include <openssl/rand.h>
20 #include <keymaster/android_keymaster_utils.h>
21 
22 #include <keymaster/km_openssl/openssl_err.h>
23 
24 namespace keymaster {
25 
26 keymaster_error_t ec_get_group_size(const EC_GROUP* group, size_t* key_size_bits) {
27     switch (EC_GROUP_get_curve_name(group)) {
28     case NID_secp224r1:
29         *key_size_bits = 224;
30         break;
31     case NID_X9_62_prime256v1:
32         *key_size_bits = 256;
33         break;
34     case NID_secp384r1:
35         *key_size_bits = 384;
36         break;
37     case NID_secp521r1:
38         *key_size_bits = 521;
39         break;
40     default:
41         return KM_ERROR_UNSUPPORTED_EC_FIELD;
42     }
43     return KM_ERROR_OK;
44 }
45 
46 EC_GROUP* ec_get_group(keymaster_ec_curve_t curve) {
47     switch (curve) {
48     case KM_EC_CURVE_P_224:
49         return EC_GROUP_new_by_curve_name(NID_secp224r1);
50         break;
51     case KM_EC_CURVE_P_256:
52         return EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
53         break;
54     case KM_EC_CURVE_P_384:
55         return EC_GROUP_new_by_curve_name(NID_secp384r1);
56         break;
57     case KM_EC_CURVE_P_521:
58         return EC_GROUP_new_by_curve_name(NID_secp521r1);
59         break;
60     default:
61         return nullptr;
62         break;
63     }
64 }
65 
66 static int convert_to_evp(keymaster_algorithm_t algorithm) {
67     switch (algorithm) {
68     case KM_ALGORITHM_RSA:
69         return EVP_PKEY_RSA;
70     case KM_ALGORITHM_EC:
71         return EVP_PKEY_EC;
72     default:
73         return -1;
74     };
75 }
76 
77 keymaster_error_t convert_pkcs8_blob_to_evp(const uint8_t* key_data, size_t key_length,
78                                             keymaster_algorithm_t expected_algorithm,
79                                             UniquePtr<EVP_PKEY, EVP_PKEY_Delete>* pkey) {
80     if (key_data == nullptr || key_length <= 0)
81         return KM_ERROR_INVALID_KEY_BLOB;
82 
83     UniquePtr<PKCS8_PRIV_KEY_INFO, PKCS8_PRIV_KEY_INFO_Delete> pkcs8(
84         d2i_PKCS8_PRIV_KEY_INFO(nullptr, &key_data, key_length));
85     if (pkcs8.get() == nullptr)
86         return TranslateLastOpenSslError(true /* log_message */);
87 
88     pkey->reset(EVP_PKCS82PKEY(pkcs8.get()));
89     if (!pkey->get())
90         return TranslateLastOpenSslError(true /* log_message */);
91 
92     if (EVP_PKEY_type((*pkey)->type) != convert_to_evp(expected_algorithm)) {
93         LOG_E("EVP key algorithm was %d, not the expected %d", EVP_PKEY_type((*pkey)->type),
94               convert_to_evp(expected_algorithm));
95         return KM_ERROR_INVALID_KEY_BLOB;
96     }
97 
98     return KM_ERROR_OK;
99 }
100 
101 keymaster_error_t KeyMaterialToEvpKey(keymaster_key_format_t key_format,
102                                       const KeymasterKeyBlob& key_material,
103                                       keymaster_algorithm_t expected_algorithm,
104                                       UniquePtr<EVP_PKEY, EVP_PKEY_Delete>* pkey) {
105     if (key_format != KM_KEY_FORMAT_PKCS8)
106         return KM_ERROR_UNSUPPORTED_KEY_FORMAT;
107 
108     return convert_pkcs8_blob_to_evp(key_material.key_material, key_material.key_material_size,
109                                      expected_algorithm, pkey);
110 }
111 
112 keymaster_error_t EvpKeyToKeyMaterial(const EVP_PKEY* pkey, KeymasterKeyBlob* key_blob) {
113     int key_data_size = i2d_PrivateKey(pkey, nullptr /* key_data*/);
114     if (key_data_size <= 0)
115         return TranslateLastOpenSslError();
116 
117     if (!key_blob->Reset(key_data_size))
118         return KM_ERROR_MEMORY_ALLOCATION_FAILED;
119 
120     uint8_t* tmp = key_blob->writable_data();
121     i2d_PrivateKey(pkey, &tmp);
122 
123     return KM_ERROR_OK;
124 }
125 
126 size_t ec_group_size_bits(EC_KEY* ec_key) {
127     const EC_GROUP* group = EC_KEY_get0_group(ec_key);
128     UniquePtr<BN_CTX, BN_CTX_Delete> bn_ctx(BN_CTX_new());
129     UniquePtr<BIGNUM, BIGNUM_Delete> order(BN_new());
130     if (!EC_GROUP_get_order(group, order.get(), bn_ctx.get())) {
131         LOG_E("Failed to get EC group order", 0);
132         return 0;
133     }
134     return BN_num_bits(order.get());
135 }
136 
137 keymaster_error_t GenerateRandom(uint8_t* buf, size_t length) {
138     if (RAND_bytes(buf, length) != 1)
139         return KM_ERROR_UNKNOWN_ERROR;
140     return KM_ERROR_OK;
141 }
142 
143 }  // namespace keymaster
144