1 /*
2  * Copyright 2014 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/symmetric_key.h>
18 
19 #include <assert.h>
20 
21 #include <openssl/err.h>
22 #include <openssl/rand.h>
23 
24 #include <keymaster/android_keymaster_utils.h>
25 #include <keymaster/keymaster_context.h>
26 #include <keymaster/km_openssl/aes_key.h>
27 #include <keymaster/km_openssl/hmac_key.h>
28 #include <keymaster/km_openssl/openssl_err.h>
29 #include <keymaster/logger.h>
30 
31 namespace keymaster {
32 
33 keymaster_error_t SymmetricKeyFactory::GenerateKey(const AuthorizationSet& key_description,
34                                                    KeymasterKeyBlob* key_blob,
35                                                    AuthorizationSet* hw_enforced,
36                                                    AuthorizationSet* sw_enforced) const {
37     if (!key_blob || !hw_enforced || !sw_enforced)
38         return KM_ERROR_OUTPUT_PARAMETER_NULL;
39 
40     uint32_t key_size_bits;
41     if (!key_description.GetTagValue(TAG_KEY_SIZE, &key_size_bits) ||
42         !key_size_supported(key_size_bits))
43         return KM_ERROR_UNSUPPORTED_KEY_SIZE;
44 
45     keymaster_error_t error = validate_algorithm_specific_new_key_params(key_description);
46     if (error != KM_ERROR_OK)
47         return error;
48 
49     size_t key_data_size = key_size_bytes(key_size_bits);
50     KeymasterKeyBlob key_material(key_data_size);
51     if (!key_material.key_material)
52         return KM_ERROR_MEMORY_ALLOCATION_FAILED;
53 
54     error = random_source_.GenerateRandom(key_material.writable_data(), key_data_size);
55     if (error != KM_ERROR_OK) {
56         LOG_E("Error generating %d bit symmetric key", key_size_bits);
57         return error;
58     }
59 
60     return blob_maker_.CreateKeyBlob(key_description, KM_ORIGIN_GENERATED, key_material, key_blob,
61                                      hw_enforced, sw_enforced);
62 }
63 
64 keymaster_error_t SymmetricKeyFactory::ImportKey(const AuthorizationSet& key_description,
65                                                  keymaster_key_format_t input_key_material_format,
66                                                  const KeymasterKeyBlob& input_key_material,
67                                                  KeymasterKeyBlob* output_key_blob,
68                                                  AuthorizationSet* hw_enforced,
69                                                  AuthorizationSet* sw_enforced) const {
70     if (!output_key_blob || !hw_enforced || !sw_enforced)
71         return KM_ERROR_OUTPUT_PARAMETER_NULL;
72 
73     AuthorizationSet authorizations(key_description);
74 
75     uint32_t key_bits;
76     if (!authorizations.GetTagValue(TAG_KEY_SIZE, &key_bits)) {
77         // Determine key size if not provided.
78         key_bits = key_size_bits(input_key_material.key_material_size);
79         authorizations.push_back(TAG_KEY_SIZE, key_bits);
80     }
81 
82     keymaster_error_t error = validate_algorithm_specific_new_key_params(key_description);
83     if (error != KM_ERROR_OK) return error;
84     if (!key_size_supported(key_bits)) return KM_ERROR_UNSUPPORTED_KEY_SIZE;
85     if (input_key_material_format != KM_KEY_FORMAT_RAW) return KM_ERROR_UNSUPPORTED_KEY_FORMAT;
86 
87     if (key_bits != key_size_bits(input_key_material.key_material_size)) {
88         LOG_E("Expected %d-bit key data but got %d-bit key", key_bits,
89               key_size_bits(input_key_material.key_material_size));
90         return KM_ERROR_INVALID_KEY_BLOB;
91     }
92 
93     return blob_maker_.CreateKeyBlob(authorizations, KM_ORIGIN_IMPORTED, input_key_material,
94                                    output_key_blob, hw_enforced, sw_enforced);
95 }
96 
97 static const keymaster_key_format_t supported_import_formats[] = {KM_KEY_FORMAT_RAW};
98 const keymaster_key_format_t*
99 SymmetricKeyFactory::SupportedImportFormats(size_t* format_count) const {
100     *format_count = array_length(supported_import_formats);
101     return supported_import_formats;
102 }
103 
104 SymmetricKey::SymmetricKey(KeymasterKeyBlob&& key_material,
105                            AuthorizationSet&& hw_enforced, AuthorizationSet&& sw_enforced,
106                            const KeyFactory* key_factory)
107     : Key(move(hw_enforced), move(sw_enforced), key_factory) {
108     key_material_ = move(key_material);
109 }
110 
111 SymmetricKey::~SymmetricKey() {}
112 
113 }  // namespace keymaster
114