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 "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/logger.h>
26 #include <keymaster/keymaster_context.h>
27
28 #include "aes_key.h"
29 #include "hmac_key.h"
30 #include "openssl_err.h"
31
32 namespace keymaster {
33
GenerateKey(const AuthorizationSet & key_description,KeymasterKeyBlob * key_blob,AuthorizationSet * hw_enforced,AuthorizationSet * sw_enforced) const34 keymaster_error_t SymmetricKeyFactory::GenerateKey(const AuthorizationSet& key_description,
35 KeymasterKeyBlob* key_blob,
36 AuthorizationSet* hw_enforced,
37 AuthorizationSet* sw_enforced) const {
38 if (!key_blob || !hw_enforced || !sw_enforced)
39 return KM_ERROR_OUTPUT_PARAMETER_NULL;
40
41 uint32_t key_size_bits;
42 if (!key_description.GetTagValue(TAG_KEY_SIZE, &key_size_bits) ||
43 !key_size_supported(key_size_bits))
44 return KM_ERROR_UNSUPPORTED_KEY_SIZE;
45
46 keymaster_error_t error = validate_algorithm_specific_new_key_params(key_description);
47 if (error != KM_ERROR_OK)
48 return error;
49
50 size_t key_data_size = key_size_bits / 8;
51 KeymasterKeyBlob key_material(key_data_size);
52 if (!key_material.key_material)
53 return KM_ERROR_MEMORY_ALLOCATION_FAILED;
54
55 error = context_->GenerateRandom(key_material.writable_data(), key_data_size);
56 if (error != KM_ERROR_OK) {
57 LOG_E("Error generating %d bit symmetric key", key_size_bits);
58 return error;
59 }
60
61 return context_->CreateKeyBlob(key_description, KM_ORIGIN_GENERATED, key_material, key_blob,
62 hw_enforced, sw_enforced);
63 }
64
ImportKey(const AuthorizationSet & key_description,keymaster_key_format_t input_key_material_format,const KeymasterKeyBlob & input_key_material,KeymasterKeyBlob * output_key_blob,AuthorizationSet * hw_enforced,AuthorizationSet * sw_enforced) const65 keymaster_error_t SymmetricKeyFactory::ImportKey(const AuthorizationSet& key_description,
66 keymaster_key_format_t input_key_material_format,
67 const KeymasterKeyBlob& input_key_material,
68 KeymasterKeyBlob* output_key_blob,
69 AuthorizationSet* hw_enforced,
70 AuthorizationSet* sw_enforced) const {
71 if (!output_key_blob || !hw_enforced || !sw_enforced)
72 return KM_ERROR_OUTPUT_PARAMETER_NULL;
73
74 AuthorizationSet authorizations(key_description);
75
76 uint32_t key_size_bits;
77 if (!authorizations.GetTagValue(TAG_KEY_SIZE, &key_size_bits)) {
78 // Default key size if not specified.
79 key_size_bits = input_key_material.key_material_size * 8;
80 authorizations.push_back(TAG_KEY_SIZE, key_size_bits);
81 }
82
83 keymaster_error_t error = validate_algorithm_specific_new_key_params(key_description);
84 if (error != KM_ERROR_OK)
85 return error;
86
87 if (!key_size_supported(key_size_bits))
88 return KM_ERROR_UNSUPPORTED_KEY_SIZE;
89
90 if (input_key_material_format != KM_KEY_FORMAT_RAW)
91 return KM_ERROR_UNSUPPORTED_KEY_FORMAT;
92
93 if (key_size_bits != input_key_material.key_material_size * 8) {
94 LOG_E("Expected %d-bit key data but got %d bits", key_size_bits,
95 input_key_material.key_material_size * 8);
96 return KM_ERROR_INVALID_KEY_BLOB;
97 }
98
99 return context_->CreateKeyBlob(authorizations, KM_ORIGIN_IMPORTED, input_key_material,
100 output_key_blob, hw_enforced, sw_enforced);
101 }
102
103 static const keymaster_key_format_t supported_import_formats[] = {KM_KEY_FORMAT_RAW};
104 const keymaster_key_format_t*
SupportedImportFormats(size_t * format_count) const105 SymmetricKeyFactory::SupportedImportFormats(size_t* format_count) const {
106 *format_count = array_length(supported_import_formats);
107 return supported_import_formats;
108 }
109
SymmetricKey(const KeymasterKeyBlob & key_material,const AuthorizationSet & hw_enforced,const AuthorizationSet & sw_enforced,keymaster_error_t * error)110 SymmetricKey::SymmetricKey(const KeymasterKeyBlob& key_material,
111 const AuthorizationSet& hw_enforced, const AuthorizationSet& sw_enforced,
112 keymaster_error_t* error)
113 : Key(hw_enforced, sw_enforced, error) {
114 if (*error != KM_ERROR_OK)
115 return;
116
117 uint8_t* tmp = dup_buffer(key_material.key_material, key_material.key_material_size);
118 if (tmp) {
119 key_data_.reset(tmp);
120 key_data_size_ = key_material.key_material_size;
121 *error = KM_ERROR_OK;
122 } else {
123 *error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
124 }
125 }
126
~SymmetricKey()127 SymmetricKey::~SymmetricKey() {
128 memset_s(key_data_.get(), 0, key_data_size_);
129 }
130
key_material(UniquePtr<uint8_t[]> * key_material,size_t * size) const131 keymaster_error_t SymmetricKey::key_material(UniquePtr<uint8_t[]>* key_material,
132 size_t* size) const {
133 *size = key_data_size_;
134 key_material->reset(new (std::nothrow) uint8_t[*size]);
135 if (!key_material->get())
136 return KM_ERROR_MEMORY_ALLOCATION_FAILED;
137 memcpy(key_material->get(), key_data_.get(), *size);
138 return KM_ERROR_OK;
139 }
140
141 } // namespace keymaster
142