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 "hmac_key.h"
18
19 #include <new>
20
21 #include <openssl/err.h>
22 #include <openssl/rand.h>
23
24 #include "hmac_operation.h"
25
26 namespace keymaster {
27
28 static HmacSignOperationFactory sign_factory;
29 static HmacVerifyOperationFactory verify_factory;
30
GetOperationFactory(keymaster_purpose_t purpose) const31 OperationFactory* HmacKeyFactory::GetOperationFactory(keymaster_purpose_t purpose) const {
32 switch (purpose) {
33 case KM_PURPOSE_SIGN:
34 return &sign_factory;
35 case KM_PURPOSE_VERIFY:
36 return &verify_factory;
37 default:
38 return nullptr;
39 }
40 }
41
LoadKey(const KeymasterKeyBlob & key_material,const AuthorizationSet &,const AuthorizationSet & hw_enforced,const AuthorizationSet & sw_enforced,UniquePtr<Key> * key) const42 keymaster_error_t HmacKeyFactory::LoadKey(const KeymasterKeyBlob& key_material,
43 const AuthorizationSet& /* additional_params */,
44 const AuthorizationSet& hw_enforced,
45 const AuthorizationSet& sw_enforced,
46 UniquePtr<Key>* key) const {
47 if (!key)
48 return KM_ERROR_OUTPUT_PARAMETER_NULL;
49
50 uint32_t min_mac_length;
51 if (!hw_enforced.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length) &&
52 !sw_enforced.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length)) {
53 LOG_E("HMAC key must have KM_TAG_MIN_MAC_LENGTH", 0);
54 return KM_ERROR_INVALID_KEY_BLOB;
55 }
56
57 keymaster_error_t error;
58 key->reset(new (std::nothrow) HmacKey(key_material, hw_enforced, sw_enforced, &error));
59 if (!key->get())
60 error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
61 return error;
62 }
63
validate_algorithm_specific_new_key_params(const AuthorizationSet & key_description) const64 keymaster_error_t HmacKeyFactory::validate_algorithm_specific_new_key_params(
65 const AuthorizationSet& key_description) const {
66 uint32_t min_mac_length_bits;
67 if (!key_description.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length_bits))
68 return KM_ERROR_MISSING_MIN_MAC_LENGTH;
69
70 keymaster_digest_t digest;
71 if (!key_description.GetTagValue(TAG_DIGEST, &digest)) {
72 LOG_E("%d digests specified for HMAC key", key_description.GetTagCount(TAG_DIGEST));
73 return KM_ERROR_UNSUPPORTED_DIGEST;
74 }
75
76 size_t hash_size_bits = 0;
77 switch (digest) {
78 case KM_DIGEST_NONE:
79 return KM_ERROR_UNSUPPORTED_DIGEST;
80 case KM_DIGEST_MD5:
81 hash_size_bits = 128;
82 break;
83 case KM_DIGEST_SHA1:
84 hash_size_bits = 160;
85 break;
86 case KM_DIGEST_SHA_2_224:
87 hash_size_bits = 224;
88 break;
89 case KM_DIGEST_SHA_2_256:
90 hash_size_bits = 256;
91 break;
92 case KM_DIGEST_SHA_2_384:
93 hash_size_bits = 384;
94 break;
95 case KM_DIGEST_SHA_2_512:
96 hash_size_bits = 512;
97 break;
98 };
99
100 if (hash_size_bits == 0) {
101 // digest was not matched
102 return KM_ERROR_UNSUPPORTED_DIGEST;
103 }
104
105 if (min_mac_length_bits % 8 != 0 || min_mac_length_bits > hash_size_bits)
106 return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
107
108 if (min_mac_length_bits < kMinHmacLengthBits)
109 return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
110
111 return KM_ERROR_OK;
112 }
113
114 } // namespace keymaster
115