1 // Copyright 2022 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 package com.google.crypto.tink.aead; 18 19 import com.google.crypto.tink.Key; 20 import com.google.crypto.tink.util.Bytes; 21 22 /** Represents functions to encrypt and decrypt data using AEAD. */ 23 public abstract class AeadKey extends Key { 24 /** 25 * Returns a {@link Bytes} instance which is prefixed to the ciphertext. 26 * 27 * <p>In order to make key rotation more efficient, Tink allows every Aead key to be prefixed with 28 * a sequence of bytes. When decrypting data, only keys with matching prefix have to be tried. 29 * 30 * <p>Note that a priori, the output prefix may not be unique in a keyset (i.e., different keys in 31 * a keyset may have the same prefix or, one prefix may be a prefix of the other). To avoid this, 32 * built in Tink keys use the convention that the prefix is either '0x00<big endian key id>' or 33 * '0x01<big endian key id>'. See the Tink keys for details. 34 */ getOutputPrefix()35 public abstract Bytes getOutputPrefix(); 36 /** Returns the parameters of this key. */ 37 @Override getParameters()38 public abstract AeadParameters getParameters(); 39 } 40