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_DAEAD_AES_SIV_PARAMETERS_H_ 18 #define TINK_DAEAD_AES_SIV_PARAMETERS_H_ 19 20 #include "tink/daead/deterministic_aead_parameters.h" 21 #include "tink/util/statusor.h" 22 23 namespace crypto { 24 namespace tink { 25 26 // Describes the parameters of an `AesSivKey`. 27 class AesSivParameters : public DeterministicAeadParameters { 28 public: 29 // Description of the output prefix prepended to the ciphertext. 30 enum class Variant : int { 31 // Prepends '0x01<big endian key id>' to the ciphertext. 32 kTink = 1, 33 // Prepends '0x00<big endian key id>' to the ciphertext. 34 kCrunchy = 2, 35 // Does not prepend any prefix (i.e., keys must have no ID requirement). 36 kNoPrefix = 3, 37 // Added to guard from failures that may be caused by future expansions. 38 kDoNotUseInsteadUseDefaultWhenWritingSwitchStatements = 20, 39 }; 40 41 // Copyable and movable. 42 AesSivParameters(const AesSivParameters& other) = default; 43 AesSivParameters& operator=(const AesSivParameters& other) = default; 44 AesSivParameters(AesSivParameters&& other) = default; 45 AesSivParameters& operator=(AesSivParameters&& other) = default; 46 47 // Creates `AesSivParameters` object from `key_size_in_bytes` and `variant`. 48 // Only allows 32-, 48-, and 64-byte key sizes as specified in RFC 5297. 49 static util::StatusOr<AesSivParameters> Create(int key_size_in_bytes, 50 Variant variant); 51 KeySizeInBytes()52 int KeySizeInBytes() const { return key_size_in_bytes_; } 53 GetVariant()54 Variant GetVariant() const { return variant_; } 55 HasIdRequirement()56 bool HasIdRequirement() const override { 57 return variant_ != Variant::kNoPrefix; 58 } 59 60 bool operator==(const Parameters& other) const override; 61 62 private: AesSivParameters(int key_size_in_bytes,Variant variant)63 AesSivParameters(int key_size_in_bytes, Variant variant) 64 : key_size_in_bytes_(key_size_in_bytes), variant_(variant) {} 65 66 int key_size_in_bytes_; 67 Variant variant_; 68 }; 69 70 } // namespace tink 71 } // namespace crypto 72 73 #endif // TINK_DAEAD_AES_SIV_PARAMETERS_H_ 74