1// Copyright 2021 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 17package hpke 18 19// kem is a package-internal interface for the Hybrid Public Key Encryption 20// (HPKE) key encapsulation mechanism (KEM). 21// 22// The HPKE RFC is available at 23// https://www.rfc-editor.org/rfc/rfc9180.html. 24type kem interface { 25 // encapsulate generates and encapsulates a shared secret using 26 // recipientPubKey. It returns the raw shared secret and encapsulated key. 27 // The HPKE RFC refers to this function as Encap(). It is used by the sender. 28 encapsulate(recipientPubKey []byte) ([]byte, []byte, error) 29 30 // decapsulate extracts the shared secret from encapsulatedKey using 31 // recipientPrivKey. It returns the raw shared secret. The HPKE RFC refers 32 // to this function as Decap(). It is used by the recipient. 33 decapsulate(encapsulatedKey, recipientPrivKey []byte) ([]byte, error) 34 35 // id returns the HPKE KEM algorithm identifier for the underlying KEM 36 // implementation. 37 // 38 // https://www.rfc-editor.org/rfc/rfc9180.html#section-7.1 39 id() uint16 40 41 // encapsulatedKeyLength returns the length of the encapsulated key, 42 // corresponding to Nenc in the following table. 43 // 44 // https://www.rfc-editor.org/rfc/rfc9180.html#section-7.1 45 encapsulatedKeyLength() int 46} 47