| // Copyright 2017 Google Inc. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #ifndef TINK_HYBRID_DECRYPT_H_ |
| #define TINK_HYBRID_DECRYPT_H_ |
| |
| #include "cc/util/statusor.h" |
| #include "google/protobuf/stubs/stringpiece.h" |
| |
| namespace crypto { |
| namespace tink { |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // The interface for hybrid decryption. |
| // |
| // Implementations of this interface are secure against adaptive |
| // chosen ciphertext attacks. In addition to 'plaintext' the |
| // encryption takes an extra parameter 'context_info', which usually |
| // is public data implicit from the context, but should be bound to |
| // the resulting ciphertext: upon decryption the ciphertext allows for |
| // checking the integrity of 'context_info' (but there are no |
| // guarantees wrt. to secrecy or authenticity of 'context_info'). |
| // |
| // 'context_info' can be empty or null, but to ensure the correct |
| // decryption of the ciphertext the same value must be provided |
| // as was used during encryption operation (cf. HybridEncrypt-interface). |
| // |
| // A concrete instantiation of this interface can implement the |
| // binding of 'context_info' to the ciphertext in various ways, for |
| // example: |
| // |
| // - use 'context_info' as "associated data"-input for the employed |
| // AEAD symmetric encryption (cf. https://tools.ietf.org/html/rfc5116). |
| // - use 'context_info' as "CtxInfo"-input for HKDF (if the implementation uses |
| // HKDF as key derivation function, cf. https://tools.ietf.org/html/rfc5869). |
| class HybridDecrypt { |
| public: |
| // Decrypts 'ciphertext' verifying the integrity of 'context_info'. |
| virtual crypto::tink::util::StatusOr<std::string> Decrypt( |
| google::protobuf::StringPiece ciphertext, |
| google::protobuf::StringPiece context_info) const = 0; |
| |
| virtual ~HybridDecrypt() {} |
| }; |
| |
| } // namespace tink |
| } // namespace crypto |
| |
| #endif // TINK_HYBRID_DECRYPT_H_ |