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package eu.siacs.conversations.crypto.axolotl;
import android.util.Base64;
import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.InvalidKeyException;
import java.util.HashSet;
import java.util.Set;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import eu.siacs.conversations.entities.Contact;
import eu.siacs.conversations.xml.Element;
public class XmppAxolotlMessage {
private byte[] innerKey;
private byte[] ciphertext;
private byte[] iv;
private final Set<XmppAxolotlMessageHeader> headers;
private final Contact contact;
private final int sourceDeviceId;
public static class XmppAxolotlMessageHeader {
private final int recipientDeviceId;
private final byte[] content;
public XmppAxolotlMessageHeader(int deviceId, byte[] content) {
this.recipientDeviceId = deviceId;
this.content = content;
}
public XmppAxolotlMessageHeader(Element header) {
if("header".equals(header.getName())) {
this.recipientDeviceId = Integer.parseInt(header.getAttribute("rid"));
this.content = Base64.decode(header.getContent(),Base64.DEFAULT);
} else {
throw new IllegalArgumentException("Argument not a <header> Element!");
}
}
public int getRecipientDeviceId() {
return recipientDeviceId;
}
public byte[] getContents() {
return content;
}
public Element toXml() {
Element headerElement = new Element("header");
// TODO: generate XML
headerElement.setAttribute("rid", getRecipientDeviceId());
headerElement.setContent(Base64.encodeToString(getContents(), Base64.DEFAULT));
return headerElement;
}
}
public static class XmppAxolotlPlaintextMessage {
private final AxolotlService.XmppAxolotlSession session;
private final String plaintext;
public XmppAxolotlPlaintextMessage(AxolotlService.XmppAxolotlSession session, String plaintext) {
this.session = session;
this.plaintext = plaintext;
}
public String getPlaintext() {
return plaintext;
}
}
public XmppAxolotlMessage(Contact contact, Element axolotlMessage) {
this.contact = contact;
this.sourceDeviceId = Integer.parseInt(axolotlMessage.getAttribute("id"));
this.headers = new HashSet<>();
for(Element child:axolotlMessage.getChildren()) {
switch(child.getName()) {
case "header":
headers.add(new XmppAxolotlMessageHeader(child));
break;
case "message":
iv = Base64.decode(child.getAttribute("iv"),Base64.DEFAULT);
ciphertext = Base64.decode(child.getContent(),Base64.DEFAULT);
break;
default:
break;
}
}
}
public XmppAxolotlMessage(Contact contact, int sourceDeviceId, String plaintext) {
this.contact = contact;
this.sourceDeviceId = sourceDeviceId;
this.headers = new HashSet<>();
this.encrypt(plaintext);
}
private void encrypt(String plaintext) {
try {
KeyGenerator generator = KeyGenerator.getInstance("AES");
generator.init(128);
SecretKey secretKey = generator.generateKey();
Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
this.innerKey = secretKey.getEncoded();
this.iv = cipher.getIV();
this.ciphertext = cipher.doFinal(plaintext.getBytes());
} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
| IllegalBlockSizeException | BadPaddingException e) {
}
}
public Contact getContact() {
return this.contact;
}
public int getSenderDeviceId() {
return sourceDeviceId;
}
public byte[] getCiphertext() {
return ciphertext;
}
public Set<XmppAxolotlMessageHeader> getHeaders() {
return headers;
}
public void addHeader(XmppAxolotlMessageHeader header) {
headers.add(header);
}
public byte[] getInnerKey(){
return innerKey;
}
public byte[] getIV() {
return this.iv;
}
public Element toXml() {
// TODO: generate outer XML, add in header XML
Element message= new Element("axolotl_message", AxolotlService.PEP_PREFIX);
message.setAttribute("id", sourceDeviceId);
for(XmppAxolotlMessageHeader header: headers) {
message.addChild(header.toXml());
}
Element payload = message.addChild("message");
payload.setAttribute("iv",Base64.encodeToString(iv, Base64.DEFAULT));
payload.setContent(Base64.encodeToString(ciphertext,Base64.DEFAULT));
return message;
}
public XmppAxolotlPlaintextMessage decrypt(AxolotlService.XmppAxolotlSession session, byte[] key) {
XmppAxolotlPlaintextMessage plaintextMessage = null;
try {
Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
SecretKeySpec keySpec = new SecretKeySpec(key, "AES");
IvParameterSpec ivSpec = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
String plaintext = new String(cipher.doFinal(ciphertext));
plaintextMessage = new XmppAxolotlPlaintextMessage(session, plaintext);
} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
| InvalidAlgorithmParameterException | IllegalBlockSizeException
| BadPaddingException e) {
throw new AssertionError(e);
}
return plaintextMessage;
}
}
|
