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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 <keymaster/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& /* 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 
     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