| // 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 hybrid |
| |
| import ( |
| "bytes" |
| |
| "github.com/google/tink/go/tink" |
| ) |
| |
| // EciesAeadHkdfHybridEncrypt is an instance of ECIES encryption with HKDF-KEM (key encapsulation mechanism) |
| // and AEAD-DEM (data encapsulation mechanism). |
| type EciesAeadHkdfHybridEncrypt struct { |
| publicKey *ECPublicKey |
| hkdfSalt []byte |
| hkdfHMACAlgo string |
| pointFormat string |
| demHelper EciesAeadHkdfDemHelper |
| } |
| |
| var _ tink.HybridEncrypt = (*EciesAeadHkdfHybridEncrypt)(nil) |
| |
| // NewEciesAeadHkdfHybridEncrypt returns ECIES encryption construct with HKDF-KEM (key encapsulation mechanism) |
| // and AEAD-DEM (data encapsulation mechanism). |
| func NewEciesAeadHkdfHybridEncrypt(pub *ECPublicKey, hkdfSalt []byte, hkdfHMACAlgo string, ptFormat string, demHelper EciesAeadHkdfDemHelper) (*EciesAeadHkdfHybridEncrypt, error) { |
| c, err := getCurve(pub.Curve.Params().Name) |
| if err != nil { |
| return nil, err |
| } |
| return &EciesAeadHkdfHybridEncrypt{ |
| publicKey: &ECPublicKey{ |
| Curve: c, |
| Point: pub.Point, |
| }, |
| hkdfSalt: hkdfSalt, |
| hkdfHMACAlgo: hkdfHMACAlgo, |
| pointFormat: ptFormat, |
| demHelper: demHelper, |
| }, nil |
| } |
| |
| // Encrypt is used to encrypt using ECIES with a HKDF-KEM and AEAD-DEM mechanisms. |
| func (e *EciesAeadHkdfHybridEncrypt) Encrypt(plaintext, contextInfo []byte) ([]byte, error) { |
| var b bytes.Buffer |
| sKem := &ECIESHKDFSenderKem{ |
| recipientPublicKey: e.publicKey, |
| } |
| kemKey, err := sKem.encapsulate(e.hkdfHMACAlgo, e.hkdfSalt, contextInfo, e.demHelper.getSymmetricKeySize(), e.pointFormat) |
| if err != nil { |
| return nil, err |
| } |
| aead, err := e.demHelper.getAead(kemKey.SymmetricKey) |
| if err != nil { |
| return nil, err |
| } |
| ct, err := aead.Encrypt(plaintext, []byte{}) |
| if err != nil { |
| return nil, err |
| } |
| b.Write(kemKey.Kem) |
| b.Write(ct) |
| return b.Bytes(), nil |
| } |