1*e7b1675dSTing-Kang Chang// Copyright 2022 Google LLC 2*e7b1675dSTing-Kang Chang// 3*e7b1675dSTing-Kang Chang// Licensed under the Apache License, Version 2.0 (the "License"); 4*e7b1675dSTing-Kang Chang// you may not use this file except in compliance with the License. 5*e7b1675dSTing-Kang Chang// You may obtain a copy of the License at 6*e7b1675dSTing-Kang Chang// 7*e7b1675dSTing-Kang Chang// http://www.apache.org/licenses/LICENSE-2.0 8*e7b1675dSTing-Kang Chang// 9*e7b1675dSTing-Kang Chang// Unless required by applicable law or agreed to in writing, software 10*e7b1675dSTing-Kang Chang// distributed under the License is distributed on an "AS IS" BASIS, 11*e7b1675dSTing-Kang Chang// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12*e7b1675dSTing-Kang Chang// See the License for the specific language governing permissions and 13*e7b1675dSTing-Kang Chang// limitations under the License. 14*e7b1675dSTing-Kang Chang// 15*e7b1675dSTing-Kang Chang//////////////////////////////////////////////////////////////////////////////// 16*e7b1675dSTing-Kang Chang 17*e7b1675dSTing-Kang Changpackage hpke 18*e7b1675dSTing-Kang Chang 19*e7b1675dSTing-Kang Changimport ( 20*e7b1675dSTing-Kang Chang "errors" 21*e7b1675dSTing-Kang Chang "fmt" 22*e7b1675dSTing-Kang Chang 23*e7b1675dSTing-Kang Chang "github.com/google/tink/go/tink" 24*e7b1675dSTing-Kang Chang pb "github.com/google/tink/go/proto/hpke_go_proto" 25*e7b1675dSTing-Kang Chang) 26*e7b1675dSTing-Kang Chang 27*e7b1675dSTing-Kang Chang// Encrypt for HPKE implements interface HybridEncrypt. 28*e7b1675dSTing-Kang Changtype Encrypt struct { 29*e7b1675dSTing-Kang Chang recipientPubKey *pb.HpkePublicKey 30*e7b1675dSTing-Kang Chang kem kem 31*e7b1675dSTing-Kang Chang kdf kdf 32*e7b1675dSTing-Kang Chang aead aead 33*e7b1675dSTing-Kang Chang} 34*e7b1675dSTing-Kang Chang 35*e7b1675dSTing-Kang Changvar _ tink.HybridEncrypt = (*Encrypt)(nil) 36*e7b1675dSTing-Kang Chang 37*e7b1675dSTing-Kang Chang// NewEncrypt constructs an Encrypt using HpkePublicKey. 38*e7b1675dSTing-Kang Changfunc NewEncrypt(recipientPubKey *pb.HpkePublicKey) (*Encrypt, error) { 39*e7b1675dSTing-Kang Chang if recipientPubKey.GetPublicKey() == nil || len(recipientPubKey.GetPublicKey()) == 0 { 40*e7b1675dSTing-Kang Chang return nil, errors.New("HpkePublicKey.PublicKey bytes are missing") 41*e7b1675dSTing-Kang Chang } 42*e7b1675dSTing-Kang Chang kem, kdf, aead, err := newPrimitivesFromProto(recipientPubKey.GetParams()) 43*e7b1675dSTing-Kang Chang if err != nil { 44*e7b1675dSTing-Kang Chang return nil, err 45*e7b1675dSTing-Kang Chang } 46*e7b1675dSTing-Kang Chang return &Encrypt{recipientPubKey, kem, kdf, aead}, nil 47*e7b1675dSTing-Kang Chang} 48*e7b1675dSTing-Kang Chang 49*e7b1675dSTing-Kang Chang// Encrypt encrypts plaintext, binding contextInfo to the resulting ciphertext. 50*e7b1675dSTing-Kang Changfunc (e *Encrypt) Encrypt(plaintext, contextInfo []byte) ([]byte, error) { 51*e7b1675dSTing-Kang Chang ctx, err := newSenderContext(e.recipientPubKey, e.kem, e.kdf, e.aead, contextInfo) 52*e7b1675dSTing-Kang Chang if err != nil { 53*e7b1675dSTing-Kang Chang return nil, fmt.Errorf("newSenderContext: %v", err) 54*e7b1675dSTing-Kang Chang } 55*e7b1675dSTing-Kang Chang 56*e7b1675dSTing-Kang Chang ciphertext, err := ctx.seal(plaintext, emptyAssociatedData) 57*e7b1675dSTing-Kang Chang if err != nil { 58*e7b1675dSTing-Kang Chang return nil, fmt.Errorf("seal: %v", err) 59*e7b1675dSTing-Kang Chang } 60*e7b1675dSTing-Kang Chang 61*e7b1675dSTing-Kang Chang return append(ctx.encapsulatedKey, ciphertext...), nil 62*e7b1675dSTing-Kang Chang} 63