1 // Copyright 2023 Google LLC 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 //////////////////////////////////////////////////////////////////////////////// 16 17 #ifndef TINK_MAC_HMAC_KEY_H_ 18 #define TINK_MAC_HMAC_KEY_H_ 19 20 #include <memory> 21 #include <string> 22 #include <utility> 23 24 #include "absl/types/optional.h" 25 #include "tink/mac/hmac_parameters.h" 26 #include "tink/mac/mac_key.h" 27 #include "tink/partial_key_access_token.h" 28 #include "tink/restricted_data.h" 29 #include "tink/util/statusor.h" 30 31 namespace crypto { 32 namespace tink { 33 34 class HmacKey : public MacKey { 35 public: 36 // Copyable and movable. 37 HmacKey(const HmacKey& other) = default; 38 HmacKey& operator=(const HmacKey& other) = default; 39 HmacKey(HmacKey&& other) = default; 40 HmacKey& operator=(HmacKey&& other) = default; 41 42 // Creates a new HMAC key. If the parameters specify a variant that uses 43 // a prefix, then the id is used to compute this prefix. 44 static util::StatusOr<HmacKey> Create(const HmacParameters& parameters, 45 const RestrictedData& key_bytes, 46 absl::optional<int> id_requirement, 47 PartialKeyAccessToken token); 48 49 // Returns the underlying HMAC key bytes. GetKeyBytes(PartialKeyAccessToken token)50 const RestrictedData& GetKeyBytes(PartialKeyAccessToken token) const { 51 return key_bytes_; 52 } 53 GetOutputPrefix()54 absl::string_view GetOutputPrefix() const override { return output_prefix_; } 55 GetParameters()56 const HmacParameters& GetParameters() const override { return parameters_; } 57 GetIdRequirement()58 absl::optional<int> GetIdRequirement() const override { 59 return id_requirement_; 60 } 61 62 bool operator==(const Key& other) const override; 63 64 private: HmacKey(const HmacParameters & parameters,const RestrictedData & key_bytes,absl::optional<int> id_requirement,std::string output_prefix)65 HmacKey(const HmacParameters& parameters, const RestrictedData& key_bytes, 66 absl::optional<int> id_requirement, std::string output_prefix) 67 : parameters_(parameters), 68 key_bytes_(key_bytes), 69 id_requirement_(id_requirement), 70 output_prefix_(std::move(output_prefix)) {} 71 72 static util::StatusOr<std::string> ComputeOutputPrefix( 73 const HmacParameters& parameters, absl::optional<int> id_requirement); 74 75 HmacParameters parameters_; 76 RestrictedData key_bytes_; 77 absl::optional<int> id_requirement_; 78 std::string output_prefix_; 79 }; 80 81 } // namespace tink 82 } // namespace crypto 83 84 #endif // TINK_MAC_HMAC_KEY_H_ 85