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/hmac_key.h>
18
19 #include <utility>
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(KeymasterKeyBlob && key_material,const AuthorizationSet &,AuthorizationSet && hw_enforced,AuthorizationSet && sw_enforced,UniquePtr<Key> * key) const42 keymaster_error_t HmacKeyFactory::LoadKey(KeymasterKeyBlob&& key_material,
43 const AuthorizationSet& /* additional_params */,
44 AuthorizationSet&& hw_enforced,
45 AuthorizationSet&& sw_enforced,
46 UniquePtr<Key>* key) const {
47 if (!key) return KM_ERROR_OUTPUT_PARAMETER_NULL;
48
49 uint32_t min_mac_length;
50 if (!hw_enforced.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length) &&
51 !sw_enforced.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length)) {
52 LOG_E("HMAC key must have KM_TAG_MIN_MAC_LENGTH");
53 return KM_ERROR_INVALID_KEY_BLOB;
54 }
55
56 key->reset(new (std::nothrow)
57 HmacKey(std::move(key_material), std::move(hw_enforced), std::move(sw_enforced),
58 this));
59 if (!key->get()) return KM_ERROR_MEMORY_ALLOCATION_FAILED;
60 return KM_ERROR_OK;
61 }
62
validate_algorithm_specific_new_key_params(const AuthorizationSet & key_description) const63 keymaster_error_t HmacKeyFactory::validate_algorithm_specific_new_key_params(
64 const AuthorizationSet& key_description) const {
65 uint32_t min_mac_length_bits;
66 if (!key_description.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length_bits))
67 return KM_ERROR_MISSING_MIN_MAC_LENGTH;
68
69 keymaster_digest_t digest;
70 if (!key_description.GetTagValue(TAG_DIGEST, &digest)) {
71 LOG_E("%zu digests specified for HMAC key", key_description.GetTagCount(TAG_DIGEST));
72 return KM_ERROR_UNSUPPORTED_DIGEST;
73 }
74
75 size_t hash_size_bits = 0;
76 switch (digest) {
77 case KM_DIGEST_NONE:
78 return KM_ERROR_UNSUPPORTED_DIGEST;
79 case KM_DIGEST_MD5:
80 hash_size_bits = 128;
81 break;
82 case KM_DIGEST_SHA1:
83 hash_size_bits = 160;
84 break;
85 case KM_DIGEST_SHA_2_224:
86 hash_size_bits = 224;
87 break;
88 case KM_DIGEST_SHA_2_256:
89 hash_size_bits = 256;
90 break;
91 case KM_DIGEST_SHA_2_384:
92 hash_size_bits = 384;
93 break;
94 case KM_DIGEST_SHA_2_512:
95 hash_size_bits = 512;
96 break;
97 };
98
99 if (hash_size_bits == 0) {
100 // digest was not matched
101 return KM_ERROR_UNSUPPORTED_DIGEST;
102 }
103
104 if (min_mac_length_bits % 8 != 0 || min_mac_length_bits > hash_size_bits)
105 return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
106
107 if (min_mac_length_bits < kMinHmacLengthBits) return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
108
109 return KM_ERROR_OK;
110 }
111
112 } // namespace keymaster
113