1 files changed, 194 insertions, 0 deletions
diff --git a/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java b/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java
new file mode 100644
index 00000000..1378c94a
--- /dev/null
+++ b/src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java
@@ -0,0 +1,194 @@
+package eu.siacs.conversations.crypto.axolotl;
+
+import android.util.Base64;
+
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+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.xml.Element;
+import eu.siacs.conversations.xmpp.jid.Jid;
+
+public class XmppAxolotlMessage {
+	private byte[] innerKey;
+	private byte[] ciphertext;
+	private byte[] iv;
+	private final Set<XmppAxolotlMessageHeader> headers;
+	private final Jid from;
+	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;
+		private final String fingerprint;
+
+		public XmppAxolotlPlaintextMessage(AxolotlService.XmppAxolotlSession session, String plaintext, String fingerprint) {
+			this.session = session;
+			this.plaintext = plaintext;
+			this.fingerprint = fingerprint;
+		}
+
+		public String getPlaintext() {
+			return plaintext;
+		}
+
+		public AxolotlService.XmppAxolotlSession getSession() {
+			return session;
+		}
+
+		public String getFingerprint() {
+			return fingerprint;
+		}
+	}
+
+	public XmppAxolotlMessage(Jid from, Element axolotlMessage) {
+		this.from = from;
+		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(Jid from, int sourceDeviceId, String plaintext) {
+		this.from = from;
+		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 Jid getFrom() {
+		return this.from;
+	}
+
+	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, String fingerprint) {
+		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, fingerprint);
+
+		} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
+				| InvalidAlgorithmParameterException | IllegalBlockSizeException
+				| BadPaddingException e) {
+			throw new AssertionError(e);
+		}
+		return plaintextMessage;
+	}
+}