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      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 
     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(const KeymasterKeyBlob& key_material,
     43                                           const AuthorizationSet& hw_enforced,
     44                                           const AuthorizationSet& sw_enforced,
     45                                           UniquePtr<Key>* key) const {
     46     if (!key)
     47         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", 0);
     53         return KM_ERROR_INVALID_KEY_BLOB;
     54     }
     55 
     56     keymaster_error_t error;
     57     key->reset(new (std::nothrow) HmacKey(key_material, hw_enforced, sw_enforced, &error));
     58     if (!key->get())
     59         error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
     60     return error;
     61 }
     62 
     63 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("%d 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)
    108         return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
    109 
    110     return KM_ERROR_OK;
    111 }
    112 
    113 }  // namespace keymaster
    114