1 // Copyright 2022 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_MAC_KEY_H_ 18 #define TINK_MAC_MAC_KEY_H_ 19 20 #include <string> 21 22 #include "tink/key.h" 23 #include "tink/mac/mac_parameters.h" 24 #include "tink/util/statusor.h" 25 26 namespace crypto { 27 namespace tink { 28 29 // Represents a function to compute/verify a message authentication code (MAC). 30 class MacKey : public Key { 31 public: 32 // Returns the bytes prefixed to every MAC tag generated by this key. 33 // 34 // In order to make key rotation more efficient, Tink allows every MAC key to 35 // have an associated tag output prefix. When verifying a tag, only keys with 36 // a matching prefix have to be tried. 37 // 38 // See https://developers.google.com/tink/wire-format#tink_output_prefix for 39 // more background information on Tink output prefixes. 40 virtual absl::string_view GetOutputPrefix() const = 0; 41 42 const MacParameters& GetParameters() const override = 0; 43 44 bool operator==(const Key& other) const override = 0; 45 }; 46 47 } // namespace tink 48 } // namespace crypto 49 50 51 #endif // TINK_MAC_MAC_KEY_H_ 52