Implement XEP-0380: Explicit Message Encryption

This adds parsing and serialization for XEP-0380: Explicit Message
Encryption in version 0.3.0.

https://xmpp.org/extensions/xep-0380.html

7 files changed, 193 insertions, 1 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5b9b7a18..c8c97ace 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@ QXmpp 1.0.1 (UNRELEASED)
 New features:
  - Add support for SCRAM-SHA-1 and SCRAM-SHA-256 (#183, @jlaine)
  - Add XEP-0367: Message Attaching (v0.3.0) (#196, @lnjX)
+ - Add XEP-0380: Explicit Message Encryption (v0.3.0) (#199, @lnjX)
  - Add XEP-0382: Spoiler messages (v0.2.0) (#195, @lnjX)
 
 QXmpp 1.0.0 (Jan 8, 2019)
diff --git a/doc/xep.doc b/doc/xep.doc
index 3daf0936..130436fc 100644
--- a/doc/xep.doc
+++ b/doc/xep.doc
@@ -42,6 +42,7 @@ Complete:
 - XEP-0319: Last User Interaction in Presence
 - XEP-0352: Client State Indication
 - XEP-0367: Message Attaching (v0.3.0)
+- XEP-0380: Explicit Message Encryption (v0.3.0)
 - XEP-0382: Spoiler messages (v0.2.0)
 
 Ongoing:
diff --git a/src/base/QXmppConstants.cpp b/src/base/QXmppConstants.cpp
index b6fab47d..80c97b56 100644
--- a/src/base/QXmppConstants.cpp
+++ b/src/base/QXmppConstants.cpp
@@ -37,6 +37,8 @@ const char* ns_stanza = "urn:ietf:params:xml:ns:xmpp-stanzas";
 const char* ns_rpc = "jabber:iq:rpc";
 // XEP-0020: Feature Negotiation
 const char* ns_feature_negotiation = "http://jabber.org/protocol/feature-neg";
+// XEP-0027: Current Jabber OpenPGP Usage
+const char* ns_legacy_openpgp = "jabber:x:encrypted";
 // XEP-0030: Service Discovery
 const char* ns_disco_info = "http://jabber.org/protocol/disco#info";
 const char* ns_disco_items = "http://jabber.org/protocol/disco#items";
@@ -135,6 +137,8 @@ const char* ns_chat_markers = "urn:xmpp:chat-markers:0";
 const char* ns_csi = "urn:xmpp:csi:0";
 // XEP-0363: HTTP File Upload
 const char* ns_http_upload = "urn:xmpp:http:upload:0";
+// XEP-0364: Current Off-the-Record Messaging Usage
+const char* ns_otr = "urn:xmpp:otr:0";
 // XEP-0367: Message Attaching
 const char* ns_message_attaching = "urn:xmpp:message-attaching:1";
 // XEP-0369: Mediated Information eXchange (MIX)
@@ -146,8 +150,14 @@ const char* ns_mix_node_participants = "urn:xmpp:mix:nodes:participants";
 const char* ns_mix_node_presence = "urn:xmpp:mix:nodes:presence";
 const char* ns_mix_node_config = "urn:xmpp:mix:nodes:config";
 const char* ns_mix_node_info = "urn:xmpp:mix:nodes:info";
+// XEP-0373: OpenPGP for XMPP
+const char* ns_ox = "urn:xmpp:openpgp:0";
+// XEP-0380: Explicit Message Encryption
+const char* ns_eme = "urn:xmpp:eme:0";
 // XEP-0382: Spoiler messages
 const char* ns_spoiler = "urn:xmpp:spoiler:0";
+// XEP-0384: OMEMO Encryption
+const char* ns_omemo = "eu.siacs.conversations.axolotl";
 // XEP-0405: Mediated Information eXchange (MIX): Participant Server Requirements
 const char* ns_mix_pam = "urn:xmpp:mix:pam:1";
 const char* ns_mix_roster = "urn:xmpp:mix:roster:0";
diff --git a/src/base/QXmppConstants_p.h b/src/base/QXmppConstants_p.h
index 5304ada4..86003970 100644
--- a/src/base/QXmppConstants_p.h
+++ b/src/base/QXmppConstants_p.h
@@ -49,6 +49,8 @@ extern const char* ns_stanza;
 extern const char* ns_rpc;
 // XEP-0020: Feature Negotiation
 extern const char* ns_feature_negotiation;
+// XEP-0027: Current Jabber OpenPGP Usage
+extern const char* ns_legacy_openpgp;
 // XEP-0030: Service Discovery
 extern const char* ns_disco_info;
 extern const char* ns_disco_items;
@@ -147,6 +149,8 @@ extern const char* ns_chat_markers;
 extern const char* ns_csi;
 // XEP-0363: HTTP File Upload
 extern const char* ns_http_upload;
+// XEP-0364: Current Off-the-Record Messaging Usage
+extern const char* ns_otr;
 // XEP-0367: Message Attaching
 extern const char* ns_message_attaching;
 // XEP-0369: Mediated Information eXchange (MIX)
@@ -158,8 +162,14 @@ extern const char* ns_mix_node_participants;
 extern const char* ns_mix_node_presence;
 extern const char* ns_mix_node_config;
 extern const char* ns_mix_node_info;
+// XEP-0373: OpenPGP for XMPP
+extern const char* ns_ox;
+// XEP-0380: Explicit Message Encryption
+extern const char* ns_eme;
 // XEP-0382: Spoiler messages
 extern const char* ns_spoiler;
+// XEP-0384: OMEMO Encryption
+extern const char* ns_omemo;
 // XEP-0405: Mediated Information eXchange (MIX): Participant Server Requirements
 extern const char* ns_mix_pam;
 extern const char* ns_mix_roster;
diff --git a/src/base/QXmppMessage.cpp b/src/base/QXmppMessage.cpp
index af4b2a6f..54ef4cd6 100644
--- a/src/base/QXmppMessage.cpp
+++ b/src/base/QXmppMessage.cpp
@@ -55,6 +55,24 @@ static const char* marker_types[] = {
     "acknowledged"
 };
 
+static const QStringList ENCRYPTION_NAMESPACES = {
+    QString(),
+    QString(),
+    ns_otr,
+    ns_legacy_openpgp,
+    ns_ox,
+    ns_omemo
+};
+
+static const QStringList ENCRYPTION_NAMES = {
+    QString(),
+    QString(),
+    QStringLiteral("OTR"),
+    QStringLiteral("Legacy OpenPGP"),
+    QStringLiteral("OpenPGP for XMPP (OX)"),
+    QStringLiteral("OMEMO")
+};
+
 static const char *ns_xhtml = "http://www.w3.org/1999/xhtml";
 
 enum StampType
@@ -110,6 +128,10 @@ public:
     QString mixUserJid;
     QString mixUserNick;
 
+    // XEP-0380: Explicit Message Encryption
+    QString encryptionMethod;
+    QString encryptionName;
+
     // XEP-0382: Spoiler messages
     bool isSpoiler = false;
     QString spoilerHint;
@@ -123,7 +145,7 @@ public:
 /// \param thread
 
 QXmppMessage::QXmppMessage(const QString& from, const QString& to, const
-                         QString& body, const QString& thread)
+                           QString& body, const QString& thread)
     : QXmppStanza(from, to)
     , d(new QXmppMessagePrivate)
 {
@@ -571,6 +593,74 @@ void QXmppMessage::setMixUserNick(const QString& mixUserNick)
     d->mixUserNick = mixUserNick;
 }
 
+/// Returns the encryption method this message is advertised to be encrypted
+/// with.
+///
+/// \note QXmppMessage::NoEncryption does not necesserily mean that the message
+/// is not encrypted; it may also be that the author of the message does not
+/// support XEP-0380: Explicit Message Encryption.
+///
+/// \note If this returns QXmppMessage::UnknownEncryption, you can still get
+/// the namespace of the encryption with \c encryptionMethodNs() and possibly
+/// also a name with \c encryptionName().
+
+QXmppMessage::EncryptionMethod QXmppMessage::encryptionMethod() const
+{
+    if (d->encryptionMethod.isEmpty())
+        return QXmppMessage::NoEncryption;
+
+    int index = ENCRYPTION_NAMESPACES.indexOf(d->encryptionMethod);
+    if (index < 0)
+        return QXmppMessage::UnknownEncryption;
+    return static_cast<QXmppMessage::EncryptionMethod>(index);
+}
+
+/// Advertises that this message is encrypted with the given encryption method.
+/// See XEP-0380: Explicit Message Encryption for details.
+
+void QXmppMessage::setEncryptionMethod(QXmppMessage::EncryptionMethod method)
+{
+    d->encryptionMethod = ENCRYPTION_NAMESPACES.at(int(method));
+}
+
+/// Returns the namespace of the advertised encryption method via. XEP-0380:
+/// Explicit Message Encryption.
+
+QString QXmppMessage::encryptionMethodNs() const
+{
+    return d->encryptionMethod;
+}
+
+/// Sets the namespace of the encryption method this message advertises to be
+/// encrypted with. See XEP-0380: Explicit Message Encryption for details.
+
+void QXmppMessage::setEncryptionMethodNs(const QString &encryptionMethod)
+{
+    d->encryptionMethod = encryptionMethod;
+}
+
+/// Returns the associated name of the encryption method this message
+/// advertises to be encrypted with. See XEP-0380: Explicit Message Encryption
+/// for details.
+
+QString QXmppMessage::encryptionName() const
+{
+    if (!d->encryptionName.isEmpty())
+        return d->encryptionName;
+    return ENCRYPTION_NAMES.at(int(encryptionMethod()));
+}
+
+/// Sets the name of the encryption method for XEP-0380: Explicit Message
+/// Encryption.
+///
+/// \note This should only be used, if the encryption method is custom and is
+/// not one of the methods listed in the XEP.
+
+void QXmppMessage::setEncryptionName(const QString &encryptionName)
+{
+    d->encryptionName = encryptionName;
+}
+
 /// Returns true, if this is a spoiler message according to XEP-0382: Spoiler
 /// messages. The spoiler hint however can still be empty.
 ///
@@ -765,6 +855,10 @@ void QXmppMessage::parse(const QDomElement &element)
         } else if (xElement.tagName() == "mix" && xElement.namespaceURI() == ns_mix) {
             d->mixUserJid = xElement.firstChildElement("jid").text();
             d->mixUserNick = xElement.firstChildElement("nick").text();
+        // XEP-0380: Explicit Message Encryption
+        } else if (xElement.tagName() == "encryption" && xElement.namespaceURI() == ns_eme) {
+            d->encryptionMethod = xElement.attribute("namespace");
+            d->encryptionName = xElement.attribute("name");
         // XEP-0382: Spoiler messages
         } else if (xElement.tagName() == "spoiler" && xElement.namespaceURI() == ns_spoiler) {
             d->isSpoiler = true;
@@ -923,6 +1017,15 @@ void QXmppMessage::toXml(QXmlStreamWriter *xmlWriter) const
         xmlWriter->writeEndElement();
     }
 
+    // XEP-0380: Explicit Message Encryption
+    if (!d->encryptionMethod.isEmpty()) {
+        xmlWriter->writeStartElement("encryption");
+        xmlWriter->writeAttribute("xmlns", ns_eme);
+        xmlWriter->writeAttribute("namespace", d->encryptionMethod);
+        helperToXmlAddAttribute(xmlWriter, "name", d->encryptionName);
+        xmlWriter->writeEndElement();
+    }
+
     // XEP-0382: Spoiler messages
     if (d->isSpoiler) {
         xmlWriter->writeStartElement("spoiler");
diff --git a/src/base/QXmppMessage.h b/src/base/QXmppMessage.h
index 330c70fe..69e2d451 100644
--- a/src/base/QXmppMessage.h
+++ b/src/base/QXmppMessage.h
@@ -66,6 +66,18 @@ public:
         Acknowledged
     };
 
+    /// This enum describes different end-to-end encryption methods. These can
+    /// be used to mark a message explicitly as encrypted with a specific
+    /// algothim. See XEP-0380: Explicit Message Encryption for details.
+    enum EncryptionMethod {
+        NoEncryption,      ///< No encryption
+        UnknownEncryption, ///< Unknown encryption
+        OTR,               ///< XEP-0364: Current Off-the-Record Messaging Usage
+        LegacyOpenPGP,     ///< XEP-0027: Current Jabber OpenPGP Usage
+        OX,                ///< XEP-0373: OpenPGP for XMPP
+        OMEMO              ///< XEP-0384: OMEMO Encryption
+    };
+
     QXmppMessage(const QString& from = QString(), const QString& to = QString(),
                  const QString& body = QString(), const QString& thread = QString());
 
@@ -151,6 +163,15 @@ public:
     QString mixUserNick() const;
     void setMixUserNick(const QString&);
 
+    // XEP-0380: Explicit Message Encryption
+    EncryptionMethod encryptionMethod() const;
+    void setEncryptionMethod(EncryptionMethod);
+    QString encryptionMethodNs() const;
+    void setEncryptionMethodNs(const QString&);
+
+    QString encryptionName() const;
+    void setEncryptionName(const QString&);
+
     // XEP-0382: Spoiler messages
     bool isSpoiler() const;
     void setIsSpoiler(bool);
diff --git a/tests/qxmppmessage/tst_qxmppmessage.cpp b/tests/qxmppmessage/tst_qxmppmessage.cpp
index 9441acef..5fe4b964 100644
--- a/tests/qxmppmessage/tst_qxmppmessage.cpp
+++ b/tests/qxmppmessage/tst_qxmppmessage.cpp
@@ -50,6 +50,7 @@ private slots:
     void testMessageCorrect();
     void testMessageAttaching();
     void testMix();
+    void testEme();
     void testSpoiler();
 };
 
@@ -114,6 +115,7 @@ void tst_QXmppMessage::testBasic()
     QCOMPARE(message.isReceiptRequested(), false);
     QCOMPARE(message.receiptId(), QString());
     QCOMPARE(message.xhtml(), QString());
+    QCOMPARE(message.encryptionMethod(), QXmppMessage::NoEncryption);
     QVERIFY(!message.isSpoiler());
     serializePacket(message, xml);
 }
@@ -663,6 +665,50 @@ void tst_QXmppMessage::testMix()
     QCOMPARE(message.mixUserNick(), QString("erik"));
 }
 
+void tst_QXmppMessage::testEme()
+{
+    // test standard encryption: OMEMO
+    const QByteArray xmlOmemo(
+        "<message to=\"foo@example.com/QXmpp\" from=\"bar@example.com/QXmpp\" type=\"normal\">"
+          "<body>This message is encrypted with OMEMO, but your client doesn't seem to support that.</body>"
+          "<encryption xmlns=\"urn:xmpp:eme:0\" namespace=\"eu.siacs.conversations.axolotl\"/>"
+        "</message>");
+
+    QXmppMessage messageOmemo;
+    parsePacket(messageOmemo, xmlOmemo);
+    QCOMPARE(messageOmemo.encryptionMethodNs(), QString("eu.siacs.conversations.axolotl"));
+    QCOMPARE(messageOmemo.encryptionMethod(), QXmppMessage::OMEMO);
+    QCOMPARE(messageOmemo.encryptionName(), QString("OMEMO"));
+    serializePacket(messageOmemo, xmlOmemo);
+
+    // test custom encryption
+    const QByteArray xmlCustom(
+        "<message to=\"foo@example.com/QXmpp\" from=\"bar@example.com/QXmpp\" type=\"normal\">"
+          "<body>This message is encrypted with CustomCrypt, but your client doesn't seem to support that.</body>"
+          "<encryption xmlns=\"urn:xmpp:eme:0\" namespace=\"im:example:customcrypt:1\" name=\"CustomCrypt\"/>"
+        "</message>");
+
+    QXmppMessage messageCustom;
+    parsePacket(messageCustom, xmlCustom);
+    QCOMPARE(messageCustom.encryptionMethodNs(), QString("im:example:customcrypt:1"));
+    QCOMPARE(messageCustom.encryptionMethod(), QXmppMessage::UnknownEncryption);
+    QCOMPARE(messageCustom.encryptionName(), QString("CustomCrypt"));
+    serializePacket(messageCustom, xmlCustom);
+
+    // test setters/getters
+    QXmppMessage message;
+    message.setEncryptionMethod(QXmppMessage::LegacyOpenPGP);
+    QCOMPARE(message.encryptionMethod(), QXmppMessage::LegacyOpenPGP);
+    QCOMPARE(message.encryptionMethodNs(), QString("jabber:x:encrypted"));
+    QCOMPARE(message.encryptionName(), QString("Legacy OpenPGP"));
+
+    message.setEncryptionMethodNs("fancyorg:encryption:fancycrypt:0");
+    message.setEncryptionName("FancyCrypt");
+    QCOMPARE(message.encryptionMethod(), QXmppMessage::UnknownEncryption);
+    QCOMPARE(message.encryptionMethodNs(), QString("fancyorg:encryption:fancycrypt:0"));
+    QCOMPARE(message.encryptionName(), QString("FancyCrypt"));
+}
+
 void tst_QXmppMessage::testSpoiler()
 {
     // test parsing with hint