| // Copyright 2017 Google Inc. |
| // |
| // 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 com.google.crypto.tink.subtle; |
| |
| import java.security.GeneralSecurityException; |
| import java.security.interfaces.ECPrivateKey; |
| import java.security.interfaces.ECPublicKey; |
| |
| /** |
| * HKDF-based KEM (key encapsulation mechanism) for ECIES recipient. |
| * |
| * @since 1.0.0 |
| */ |
| public final class EciesHkdfRecipientKem { |
| private ECPrivateKey recipientPrivateKey; |
| |
| public EciesHkdfRecipientKem(final ECPrivateKey recipientPrivateKey) { |
| this.recipientPrivateKey = recipientPrivateKey; |
| } |
| |
| public byte[] generateKey( |
| byte[] kemBytes, |
| String hmacAlgo, |
| final byte[] hkdfSalt, |
| final byte[] hkdfInfo, |
| int keySizeInBytes, |
| EllipticCurves.PointFormatType pointFormat) |
| throws GeneralSecurityException { |
| ECPublicKey ephemeralPublicKey = EllipticCurves.getEcPublicKey( |
| recipientPrivateKey.getParams(), pointFormat, kemBytes); |
| byte[] sharedSecret = EllipticCurves.computeSharedSecret( |
| recipientPrivateKey, ephemeralPublicKey); |
| return Hkdf.computeEciesHkdfSymmetricKey( |
| kemBytes, sharedSecret, hmacAlgo, hkdfSalt, hkdfInfo, keySizeInBytes); |
| } |
| } |