001/**
002 *
003 * Copyright 2017 Paul Schaub
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smackx.omemo.element;
018
019import java.util.ArrayList;
020import java.util.List;
021
022import org.jivesoftware.smack.packet.NamedElement;
023import org.jivesoftware.smack.util.XmlStringBuilder;
024import org.jivesoftware.smack.util.stringencoder.Base64;
025
026/**
027 * Header element of the message. The header contains information about the sender and the encrypted keys for
028 * the recipients, as well as the iv element for AES.
029 */
030public abstract class OmemoHeaderElement implements NamedElement {
031
032    public static final String NAME_HEADER = "header";
033    public static final String ATTR_SID = "sid";
034    public static final String ATTR_IV = "iv";
035
036    private final int sid;
037    private final List<OmemoKeyElement> keys;
038    private final byte[] iv;
039
040    public OmemoHeaderElement(int sid, List<OmemoKeyElement> keys, byte[] iv) {
041        this.sid = sid;
042        this.keys = keys;
043        this.iv = iv;
044    }
045
046    /**
047     * Return the deviceId of the sender of the message.
048     *
049     * @return senders id
050     */
051    public int getSid() {
052        return sid;
053    }
054
055    public ArrayList<OmemoKeyElement> getKeys() {
056        return new ArrayList<>(keys);
057    }
058
059    public byte[] getIv() {
060        return iv != null ? iv.clone() : null;
061    }
062
063    @Override
064    public String getElementName() {
065        return NAME_HEADER;
066    }
067
068    @Override
069    public CharSequence toXML(String enclosingNamespace) {
070        XmlStringBuilder sb = new XmlStringBuilder(this);
071        sb.attribute(ATTR_SID, getSid()).rightAngleBracket();
072
073        for (OmemoKeyElement k : getKeys()) {
074            sb.element(k);
075        }
076
077        sb.openElement(ATTR_IV).append(Base64.encodeToString(getIv())).closeElement(ATTR_IV);
078
079        return sb.closeElement(this);
080    }
081
082
083}