001/*
002 * nimbus-jose-jwt
003 *
004 * Copyright 2012-2021, Connect2id Ltd and contributors.
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use
007 * this file except in compliance with the License. You may obtain a copy of the
008 * License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software distributed
013 * under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
014 * CONDITIONS OF ANY KIND, either express or implied. See the License for the
015 * specific language governing permissions and limitations under the License.
016 */
017
018package com.nimbusds.jose.crypto;
019
020
021import com.nimbusds.jose.*;
022import com.nimbusds.jose.crypto.impl.*;
023import com.nimbusds.jose.jwk.Curve;
024import com.nimbusds.jose.jwk.OctetKeyPair;
025import com.nimbusds.jose.jwk.gen.OctetKeyPairGenerator;
026import com.nimbusds.jose.util.Pair;
027import net.jcip.annotations.ThreadSafe;
028
029import javax.crypto.SecretKey;
030import java.util.*;
031
032
033/**
034 * Elliptic Curve Diffie-Hellman Multi-recipient encrypter of
035 * {@link JWEObjectJSON JWE objects} for curves using EC JWK keys.
036 * Expects a public EC key (with a P-256, P-384, or P-521 curve).
037 *
038 * <p>Public Key Authenticated Encryption for JOSE
039 * <a href="https://datatracker.ietf.org/doc/html/draft-madden-jose-ecdh-1pu-04">ECDH-1PU</a>
040 * for more information.
041 *
042 * <p>This class is thread-safe.
043 *
044 * <p>Supports the following key management algorithms:
045 *
046 * <ul>
047 *     <li>{@link com.nimbusds.jose.JWEAlgorithm#ECDH_ES}
048 *     <li>{@link com.nimbusds.jose.JWEAlgorithm#ECDH_ES_A128KW}
049 *     <li>{@link com.nimbusds.jose.JWEAlgorithm#ECDH_ES_A192KW}
050 *     <li>{@link com.nimbusds.jose.JWEAlgorithm#ECDH_ES_A256KW}
051 * </ul>
052 *
053 * <p>Supports the following elliptic curve:
054 *
055 * <ul>
056 *     <li>{@link com.nimbusds.jose.jwk.Curve#X25519} (Curve25519)
057 * </ul>
058 *
059 * <p>Supports the following content encryption algorithms:
060 *
061 * <ul>
062 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A128CBC_HS256}
063 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A192CBC_HS384}
064 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A256CBC_HS512}
065 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A128GCM}
066 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A192GCM}
067 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A256GCM}
068 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A128CBC_HS256_DEPRECATED}
069 *     <li>{@link com.nimbusds.jose.EncryptionMethod#A256CBC_HS512_DEPRECATED}
070 *     <li>{@link com.nimbusds.jose.EncryptionMethod#XC20P}
071 * </ul>
072 *
073 * @author Alexander Martynov
074 * @version 2021-08-18
075 */
076@ThreadSafe
077public class X25519EncrypterMulti extends ECDHCryptoProvider implements JWEEncrypterMulti {
078
079    /**
080     * The supported EC JWK curves by the ECDH crypto provider class.
081     */
082    public static final Set<Curve> SUPPORTED_ELLIPTIC_CURVES;
083
084
085    static {
086        Set<Curve> curves = new LinkedHashSet<>();
087        curves.add(Curve.X25519);
088        SUPPORTED_ELLIPTIC_CURVES = Collections.unmodifiableSet(curves);
089    }
090
091    /**
092     * The list of public recipient's keys.
093     */
094    private final List<Pair<UnprotectedHeader, OctetKeyPair>> recipients;
095
096    /**
097     * Creates a curve x25519 Elliptic Curve Diffie-Hellman Multi-recipient encryptor.
098     *
099     * @param recipients The list of public recipient's keys.
100     *
101     * @throws JOSEException If the key subtype is not supported.
102     */
103    public X25519EncrypterMulti(final List<Pair<UnprotectedHeader, OctetKeyPair>> recipients)
104        throws JOSEException {
105
106        super(recipients.get(0).getRight().getCurve());
107
108        this.recipients = recipients;
109    }
110
111    @Override
112    public Set<Curve> supportedEllipticCurves() {
113        return SUPPORTED_ELLIPTIC_CURVES;
114    }
115
116    @Override
117    public JWECryptoParts encrypt(JWEHeader header, byte[] clearText) throws JOSEException {
118        // Generate ephemeral OctetKey key pair on the same curve as the consumer's public key
119        OctetKeyPair ephemeralPrivateKey = new OctetKeyPairGenerator(getCurve()).generate();
120        OctetKeyPair ephemeralPublicKey = ephemeralPrivateKey.toPublicJWK();
121
122        // Add the ephemeral public OctetKey key to the header
123        JWEHeader updatedHeader = new JWEHeader.Builder(header)
124                .ephemeralPublicKey(ephemeralPublicKey)
125                .build();
126
127        List<Pair<UnprotectedHeader, SecretKey>> sharedKeys = new ArrayList<>();
128
129        for (Pair<UnprotectedHeader, OctetKeyPair> recipient : recipients) {
130            SecretKey Z = ECDH.deriveSharedSecret(
131                    recipient.getRight().toPublicJWK(),
132                    ephemeralPrivateKey
133            );
134
135            sharedKeys.add(Pair.of(recipient.getLeft(), Z));
136        }
137
138        return encryptMulti(updatedHeader, sharedKeys, clearText);
139    }
140}