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_SIGNATURE_SIGNATURE_PRIVATE_KEY_H_ 18 #define TINK_SIGNATURE_SIGNATURE_PRIVATE_KEY_H_ 19 20 #include "absl/strings/string_view.h" 21 #include "tink/key.h" 22 #include "tink/private_key.h" 23 #include "tink/signature/signature_parameters.h" 24 #include "tink/signature/signature_public_key.h" 25 26 namespace crypto { 27 namespace tink { 28 29 // Represents a function to compute digital signatures. 30 class SignaturePrivateKey : public PrivateKey { 31 public: 32 const SignaturePublicKey& GetPublicKey() const override = 0; 33 34 // Returns the bytes prefixed to every signature generated by this key. 35 // 36 // In order to make key rotation more efficient, Tink allows every signature 37 // private key to have an associated signature output prefix. When verifying a 38 // digital signature, only keys with a matching prefix have to be tried. 39 // 40 // See https://developers.google.com/tink/wire-format#tink_output_prefix for 41 // more background information on Tink output prefixes. GetOutputPrefix()42 absl::string_view GetOutputPrefix() const { 43 return GetPublicKey().GetOutputPrefix(); 44 } 45 GetIdRequirement()46 absl::optional<int> GetIdRequirement() const override { 47 return GetPublicKey().GetIdRequirement(); 48 } 49 GetParameters()50 const SignatureParameters& GetParameters() const override { 51 return GetPublicKey().GetParameters(); 52 } 53 54 bool operator==(const Key& other) const override = 0; 55 }; 56 57 } // namespace tink 58 } // namespace crypto 59 60 #endif // TINK_SIGNATURE_SIGNATURE_PRIVATE_KEY_H_ 61