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// kdf is a package-internal interface for the Hybrid Public Key Encryption 20// (HPKE) key derivation function (KDF). 21// 22// The HPKE RFC is available at 23// https://www.rfc-editor.org/rfc/rfc9180.html. 24type kdf interface { 25 // labeledExtract extracts a pseudorandom key from salt, ikm using the 26 // HPKE-specified values suiteID, ikmLabel to facilitate domain separation 27 // and context binding. 28 // 29 // https://www.rfc-editor.org/rfc/rfc9180.html#section-4-9 30 labeledExtract(salt, ikm []byte, ikmLabel string, suiteID []byte) []byte 31 32 // labeledExpand expands the pseudorandom key prk into length pseudorandom 33 // bytes using info with other HPKE-specific values infoLabel, suiteID to 34 // facilitate domain separation and context binding. 35 // 36 // https://www.rfc-editor.org/rfc/rfc9180.html#section-4-9 37 labeledExpand(prk, info []byte, infoLabel string, suiteID []byte, length int) ([]byte, error) 38 39 // extractAndExpand calls labeledExtract and labeledExpand in order. 40 // 41 // https://www.rfc-editor.org/rfc/rfc9180.html#section-4.1-3 42 extractAndExpand(salt, ikm []byte, ikmLabel string, info []byte, infoLabel string, suiteID []byte, length int) ([]byte, error) 43 44 // id returns the HPKE KDF algorithm identifier for the underlying KDF 45 // implementation. 46 // 47 // https://www.rfc-editor.org/rfc/rfc9180.html#section-7.2 48 id() uint16 49} 50