| // 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. |
| // |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| package com.google.crypto.tink; |
| |
| import java.security.GeneralSecurityException; |
| |
| /** |
| * Interface for Deterministic Authenticated Encryption with Associated Data (Deterministic AEAD). |
| * |
| * <p>For why this interface is desirable and some of its use cases, see for example <a |
| * href="https://tools.ietf.org/html/rfc5297#section-1.3">RFC 5297 section 1.3</a>. |
| * |
| * <h3>Warning</h3> |
| * |
| * <p>Unlike {@link Aead}, implementations of this interface are not semantically secure, because |
| * encrypting the same plaintex always yields the same ciphertext. |
| * |
| * <h3>Security guarantees</h3> |
| * |
| * <p>Implementations of this interface provide 128-bit security level against multi-user attacks |
| * with up to 2^32 keys. That means if an adversary obtains 2^32 ciphertexts of the same message |
| * encrypted under 2^32 keys, they need to do 2^128 computations to obtain a single key. |
| * |
| * <p>Encryption with associated data ensures authenticity (who the sender is) and integrity (the |
| * data has not been tampered with) of that data, but not its secrecy. (see <a |
| * href="https://tools.ietf.org/html/rfc5116">RFC 5116</a>) |
| * |
| * @since 1.1.0 |
| */ |
| public interface DeterministicAead { |
| /** |
| * Deterministically encrypts {@code plaintext} with {@code associatedData} as associated |
| * authenticated data. |
| * |
| * <p><b>Warning</b> |
| * |
| * <p>Encrypting the same {@code plaintext} multiple times protects the integrity of that |
| * plaintext, but confidentiality is compromised to the extent that an attacker can determine that |
| * the same plaintext was encrypted. |
| * |
| * <p>The resulting ciphertext allows for checking authenticity and integrity of associated data |
| * ({@code associatedData}), but does not guarantee its secrecy. |
| * |
| * @return resulting ciphertext |
| */ |
| byte[] encryptDeterministically(final byte[] plaintext, final byte[] associatedData) |
| throws GeneralSecurityException; |
| |
| /** |
| * Deterministically decrypts {@code ciphertext} with {@code associatedData} as associated |
| * authenticated data. |
| * |
| * <p>The decryption verifies the authenticity and integrity of the associated data, but there are |
| * no guarantees wrt. secrecy of that data. |
| * |
| * @return resulting plaintext |
| */ |
| byte[] decryptDeterministically(final byte[] ciphertext, final byte[] associatedData) |
| throws GeneralSecurityException; |
| } |