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_AEAD_AES_GCM_PARAMETERS_H_ 18 #define TINK_AEAD_AES_GCM_PARAMETERS_H_ 19 20 #include "tink/aead/aead_parameters.h" 21 #include "tink/util/statusor.h" 22 23 namespace crypto { 24 namespace tink { 25 26 // Describes the parameters of an `AesGcmKey`. 27 class AesGcmParameters : public AeadParameters { 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 // Creates AES-GCM parameters instances. 42 class Builder { 43 public: 44 // Copyable and movable. 45 Builder(const Builder& other) = default; 46 Builder& operator=(const Builder& other) = default; 47 Builder(Builder&& other) = default; 48 Builder& operator=(Builder&& other) = default; 49 50 // Creates initially empty parameters builder. 51 Builder() = default; 52 53 Builder& SetKeySizeInBytes(int key_size); 54 Builder& SetIvSizeInBytes(int iv_size); 55 Builder& SetTagSizeInBytes(int tag_size); 56 Builder& SetVariant(Variant variant); 57 58 // Creates AES-GCM parameters object from this builder. 59 util::StatusOr<AesGcmParameters> Build(); 60 61 private: 62 int key_size_in_bytes_; 63 int iv_size_in_bytes_; 64 int tag_size_in_bytes_; 65 Variant variant_; 66 }; 67 68 // Copyable and movable. 69 AesGcmParameters(const AesGcmParameters& other) = default; 70 AesGcmParameters& operator=(const AesGcmParameters& other) = default; 71 AesGcmParameters(AesGcmParameters&& other) = default; 72 AesGcmParameters& operator=(AesGcmParameters&& other) = default; 73 KeySizeInBytes()74 int KeySizeInBytes() const { return key_size_in_bytes_; } 75 IvSizeInBytes()76 int IvSizeInBytes() const { return iv_size_in_bytes_; } 77 TagSizeInBytes()78 int TagSizeInBytes() const { return tag_size_in_bytes_; } 79 GetVariant()80 Variant GetVariant() const { return variant_; } 81 HasIdRequirement()82 bool HasIdRequirement() const override { 83 return variant_ != Variant::kNoPrefix; 84 } 85 86 bool operator==(const Parameters& other) const override; 87 88 private: AesGcmParameters(int key_size_in_bytes,int iv_size_in_bytes,int tag_size_in_bytes,Variant variant)89 AesGcmParameters(int key_size_in_bytes, int iv_size_in_bytes, 90 int tag_size_in_bytes, Variant variant) 91 : key_size_in_bytes_(key_size_in_bytes), 92 iv_size_in_bytes_(iv_size_in_bytes), 93 tag_size_in_bytes_(tag_size_in_bytes), 94 variant_(variant) {} 95 96 int key_size_in_bytes_; 97 int iv_size_in_bytes_; 98 int tag_size_in_bytes_; 99 Variant variant_; 100 }; 101 102 } // namespace tink 103 } // namespace crypto 104 105 #endif // TINK_AEAD_AES_GCM_PARAMETERS_H_ 106