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 <keymaster/new.h>
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 
31 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 
42 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)
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     key->reset(new (std::nothrow) HmacKey(move(key_material), move(hw_enforced), move(sw_enforced),
58                                           this));
59     if (!key->get())
60         return KM_ERROR_MEMORY_ALLOCATION_FAILED;
61     return KM_ERROR_OK;
62 }
63 
64 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