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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 #ifndef SYSTEM_KEYMASTER_AES_KEY_H_
     18 #define SYSTEM_KEYMASTER_AES_KEY_H_
     19 
     20 #include <openssl/aes.h>
     21 
     22 #include "symmetric_key.h"
     23 
     24 namespace keymaster {
     25 
     26 const size_t kMinGcmTagLength = 12 * 8;
     27 const size_t kMaxGcmTagLength = 16 * 8;
     28 
     29 class AesKeyFactory : public SymmetricKeyFactory {
     30   public:
     31     explicit AesKeyFactory(const SoftwareKeyBlobMaker* blob_maker,
     32                            const RandomSource* random_source) :
     33 		SymmetricKeyFactory(blob_maker, random_source) {}
     34 
     35     keymaster_algorithm_t registry_key() const { return KM_ALGORITHM_AES; }
     36 
     37     keymaster_error_t LoadKey(KeymasterKeyBlob&& key_material,
     38                               const AuthorizationSet& additional_params,
     39                               AuthorizationSet&& hw_enforced,
     40                               AuthorizationSet&& sw_enforced,
     41                               UniquePtr<Key>* key) const override;
     42 
     43     OperationFactory* GetOperationFactory(keymaster_purpose_t purpose) const override;
     44 
     45   private:
     46     bool key_size_supported(size_t key_size_bits) const override {
     47         return key_size_bits == 128 || key_size_bits == 192 || key_size_bits == 256;
     48     }
     49     keymaster_error_t validate_algorithm_specific_new_key_params(
     50         const AuthorizationSet& key_description) const override;
     51 };
     52 
     53 class AesKey : public SymmetricKey {
     54   public:
     55     AesKey(KeymasterKeyBlob&& key_material, AuthorizationSet&& hw_enforced,
     56            AuthorizationSet&& sw_enforced,
     57            const KeyFactory* key_factory)
     58         : SymmetricKey(move(key_material), move(hw_enforced), move(sw_enforced), key_factory) {}
     59 };
     60 
     61 }  // namespace keymaster
     62 
     63 #endif  // SYSTEM_KEYMASTER_AES_KEY_H_
     64