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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_HMAC_KEY_H_
     18 #define SYSTEM_KEYMASTER_HMAC_KEY_H_
     19 
     20 #include "symmetric_key.h"
     21 
     22 namespace keymaster {
     23 
     24 const size_t kMinHmacLengthBits = 64;
     25 const size_t kMinHmacKeyLengthBits = 64;
     26 const size_t kMaxHmacKeyLengthBits = 2048;  // Some RFC test cases require >1024-bit keys
     27 
     28 class HmacKeyFactory : public SymmetricKeyFactory {
     29   public:
     30     explicit HmacKeyFactory(const KeymasterContext* context) : SymmetricKeyFactory(context) {}
     31 
     32     keymaster_error_t LoadKey(const KeymasterKeyBlob& key_material,
     33                               const AuthorizationSet& additional_params,
     34                               const AuthorizationSet& hw_enforced,
     35                               const AuthorizationSet& sw_enforced,
     36                               UniquePtr<Key>* key) const override;
     37 
     38     OperationFactory* GetOperationFactory(keymaster_purpose_t purpose) const override;
     39 
     40   private:
     41     bool key_size_supported(size_t key_size_bits) const override {
     42         return key_size_bits > 0 && key_size_bits % 8 == 00 &&
     43                key_size_bits >= kMinHmacKeyLengthBits && key_size_bits <= kMaxHmacKeyLengthBits;
     44     }
     45     keymaster_error_t validate_algorithm_specific_new_key_params(
     46         const AuthorizationSet& key_description) const override;
     47 };
     48 
     49 class HmacKey : public SymmetricKey {
     50   public:
     51     HmacKey(const KeymasterKeyBlob& key_material, const AuthorizationSet& hw_enforced,
     52             const AuthorizationSet& sw_enforced, keymaster_error_t* error)
     53         : SymmetricKey(key_material, hw_enforced, sw_enforced, error) {}
     54 };
     55 
     56 }  // namespace keymaster
     57 
     58 #endif  // SYSTEM_KEYMASTER_HMAC_KEY_H_
     59