| // 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_ENCRYPT_H_ |
| #define TINK_HYBRID_ENCRYPT_H_ |
| |
| #include <string> |
| |
| #include "absl/strings/string_view.h" |
| #include "tink/util/statusor.h" |
| |
| namespace crypto { |
| namespace tink { |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // The interface for hybrid encryption. |
| // |
| // 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'). |
| // |
| // WARNING: hybrid encryption does not provide authenticity, that is the |
| // recipient of an encrypted message does not know the identity of the sender. |
| // Similar to general public-key encryption schemes the security goal of |
| // hybrid encryption is to provide privacy only. In other words, hybrid |
| // encryption is secure if and only if the recipient can accept anonymous |
| // messages or can rely on other mechanisms to authenticate the sender. |
| // |
| // 'context_info' can be empty or null, but to ensure the correct |
| // decryption of the resulting ciphertext the same value must be |
| // provided for decryption operation (cf. HybridDecrypt-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 HybridEncrypt { |
| public: |
| // Encrypts 'plaintext' binding 'context_info' to the resulting ciphertext. |
| virtual crypto::tink::util::StatusOr<std::string> Encrypt( |
| absl::string_view plaintext, absl::string_view context_info) const = 0; |
| |
| virtual ~HybridEncrypt() {} |
| }; |
| |
| } // namespace tink |
| } // namespace crypto |
| |
| #endif // TINK_HYBRID_ENCRYPT_H_ |