1 // Copyright 2017 Google Inc. 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_HYBRID_ECIES_AEAD_HKDF_DEM_HELPER_H_ 18 #define TINK_HYBRID_ECIES_AEAD_HKDF_DEM_HELPER_H_ 19 20 #include <stdint.h> 21 22 #include <memory> 23 24 #include "tink/aead.h" 25 #include "tink/daead/subtle/aead_or_daead.h" 26 #include "tink/util/protobuf_helper.h" 27 #include "tink/util/secret_data.h" 28 #include "tink/util/statusor.h" 29 #include "proto/common.pb.h" 30 #include "proto/tink.pb.h" 31 32 namespace crypto { 33 namespace tink { 34 35 // A helper for DEM (data encapsulation mechanism) of ECIES-AEAD-HKDF. 36 class EciesAeadHkdfDemHelper { 37 public: 38 // Constructs a new helper for the specified DEM key template. 39 static 40 crypto::tink::util::StatusOr<std::unique_ptr<const EciesAeadHkdfDemHelper>> 41 New(const google::crypto::tink::KeyTemplate& dem_key_template); 42 43 virtual ~EciesAeadHkdfDemHelper() = default; 44 45 // Returns the size of the DEM-key in bytes. dem_key_size_in_bytes()46 uint32_t dem_key_size_in_bytes() const { 47 return key_params_.key_size_in_bytes; 48 } 49 50 // Creates and returns a new AeadOrDaead object that uses 51 // the key material given in 'symmetric_key', which must 52 // be of length dem_key_size_in_bytes(). 53 virtual crypto::tink::util::StatusOr< 54 std::unique_ptr<crypto::tink::subtle::AeadOrDaead>> 55 GetAeadOrDaead(const util::SecretData& symmetric_key_value) const; 56 57 protected: 58 enum DemKeyType { 59 AES_GCM_KEY, 60 AES_CTR_HMAC_AEAD_KEY, 61 XCHACHA20_POLY1305_KEY, 62 AES_SIV_KEY, 63 }; 64 65 struct DemKeyParams { 66 DemKeyType key_type; 67 uint32_t key_size_in_bytes; 68 uint32_t aes_ctr_key_size_in_bytes; 69 uint32_t aes_ctr_key_iv_size_in_bytes; 70 google::crypto::tink::HashType hmac_key_hash; 71 uint32_t hmac_key_tag_size_in_bytes; 72 }; 73 EciesAeadHkdfDemHelper(const google::crypto::tink::KeyTemplate & key_template,DemKeyParams key_params)74 EciesAeadHkdfDemHelper(const google::crypto::tink::KeyTemplate& key_template, 75 DemKeyParams key_params) 76 : key_template_(key_template), key_params_(key_params) {} 77 78 static util::StatusOr<DemKeyParams> GetKeyParams( 79 const ::google::crypto::tink::KeyTemplate& key_template); 80 81 const google::crypto::tink::KeyTemplate key_template_; 82 const DemKeyParams key_params_; 83 }; 84 85 } // namespace tink 86 } // namespace crypto 87 88 #endif // TINK_HYBRID_ECIES_AEAD_HKDF_DEM_HELPER_H_ 89