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 "aes_key.h"
18
19 #include <assert.h>
20
21 #include <new>
22
23 #include <openssl/err.h>
24 #include <openssl/rand.h>
25
26 #include "aes_operation.h"
27
28 namespace keymaster {
29
30 AesEncryptionOperationFactory encrypt_factory;
31 AesDecryptionOperationFactory decrypt_factory;
32
GetOperationFactory(keymaster_purpose_t purpose) const33 OperationFactory* AesKeyFactory::GetOperationFactory(keymaster_purpose_t purpose) const {
34 switch (purpose) {
35 case KM_PURPOSE_ENCRYPT:
36 return &encrypt_factory;
37 case KM_PURPOSE_DECRYPT:
38 return &decrypt_factory;
39 default:
40 return nullptr;
41 }
42 }
43
LoadKey(const KeymasterKeyBlob & key_material,const AuthorizationSet &,const AuthorizationSet & hw_enforced,const AuthorizationSet & sw_enforced,UniquePtr<Key> * key) const44 keymaster_error_t AesKeyFactory::LoadKey(const KeymasterKeyBlob& key_material,
45 const AuthorizationSet& /* additional_params */,
46 const AuthorizationSet& hw_enforced,
47 const AuthorizationSet& sw_enforced,
48 UniquePtr<Key>* key) const {
49 if (!key)
50 return KM_ERROR_OUTPUT_PARAMETER_NULL;
51
52 uint32_t min_mac_length = 0;
53 if (hw_enforced.Contains(TAG_BLOCK_MODE, KM_MODE_GCM) ||
54 sw_enforced.Contains(TAG_BLOCK_MODE, KM_MODE_GCM)) {
55
56 if (!hw_enforced.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length) &&
57 !sw_enforced.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length)) {
58
59 LOG_E("AES-GCM key must have KM_TAG_MIN_MAC_LENGTH", 0);
60 return KM_ERROR_INVALID_KEY_BLOB;
61 }
62 }
63
64 keymaster_error_t error = KM_ERROR_OK;
65 key->reset(new (std::nothrow) AesKey(key_material, hw_enforced, sw_enforced, &error));
66 if (!key->get())
67 error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
68 return error;
69 }
70
validate_algorithm_specific_new_key_params(const AuthorizationSet & key_description) const71 keymaster_error_t AesKeyFactory::validate_algorithm_specific_new_key_params(
72 const AuthorizationSet& key_description) const {
73 if (key_description.Contains(TAG_BLOCK_MODE, KM_MODE_GCM)) {
74 uint32_t min_tag_length;
75 if (!key_description.GetTagValue(TAG_MIN_MAC_LENGTH, &min_tag_length))
76 return KM_ERROR_MISSING_MIN_MAC_LENGTH;
77
78 if (min_tag_length % 8 != 0)
79 return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
80
81 if (min_tag_length < kMinGcmTagLength || min_tag_length > kMaxGcmTagLength)
82 return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
83 } else {
84 // Not GCM
85 if (key_description.find(TAG_MIN_MAC_LENGTH) != -1) {
86 LOG_W("KM_TAG_MIN_MAC_LENGTH found for non AES-GCM key", 0);
87 return KM_ERROR_INVALID_TAG;
88 }
89 }
90
91 return KM_ERROR_OK;
92 }
93
94 } // namespace keymaster
95