DRAFT/WIP Started XEP-0373: OpenPGP for XMPP implementation

settings.gradle

@@ -26,4 +26,6 @@ include 'smack-core',
 		'smack-omemo',
 		'smack-omemo-signal',
 		'smack-omemo-signal-integration-test',
-		'smack-repl'
+		'smack-repl',
+		'smack-openpgp',
+		'smack-openpgp-bouncycastle'

smack-openpgp-bouncycastle/build.gradle

@@ -0,0 +1,12 @@
+description = """\
+Smack API for OpenPGP using Bouncycastle."""
+
+// Note that the test dependencies (junit, …) are inferred from the
+// sourceSet.test of the core subproject
+dependencies {
+	compile project(':smack-core')
+	compile project(':smack-openpgp')
+	compile 'org.bouncycastle:bcpg-jdk15on:1.56'
+	testCompile project(path: ":smack-core", configuration: "testRuntime")
+	testCompile project(path: ":smack-core", configuration: "archives")
+}

smack-openpgp-bouncycastle/src/main/java/org/jivesoftware/smackx/ox/bouncycastle/BouncycastleOpenPgpProvider.java

@@ -0,0 +1,32 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.bouncycastle;
+
+import java.io.InputStream;
+
+import org.jivesoftware.smackx.ox.OpenPgpMessage;
+import org.jivesoftware.smackx.ox.OpenPgpProvider;
+
+public class BouncycastleOpenPgpProvider implements OpenPgpProvider {
+
+    @Override
+    public OpenPgpMessage toOpenPgpMessage(InputStream is) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}

smack-openpgp-bouncycastle/src/main/java/org/jivesoftware/smackx/ox/bouncycastle/package-info.java

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * Providers for XEP-0373: OpenPGP for XMPP using Bouncycastle.
+ */
+package org.jivesoftware.smackx.ox.bouncycastle;

smack-openpgp/build.gradle

@@ -0,0 +1,10 @@
+description = """\
+Smack API for XEP-0373: OpenPGP for XMPP."""
+
+// Note that the test dependencies (junit, …) are inferred from the
+// sourceSet.test of the core subproject
+dependencies {
+	compile project(':smack-core')
+	testCompile project(path: ":smack-core", configuration: "testRuntime")
+	testCompile project(path: ":smack-core", configuration: "archives")
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/OpenPgpManager.java

@@ -0,0 +1,26 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox;
+
+import java.io.InputStream;
+
+public class OpenPgpManager {
+
+    public static OpenPgpMessage toOpenPgpMessage(InputStream is) {
+        return null;
+    }
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/OpenPgpMessage.java

@@ -0,0 +1,82 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox;
+
+import java.io.IOException;
+
+import org.jivesoftware.smackx.ox.element.CryptElement;
+import org.jivesoftware.smackx.ox.element.OpenPgpContentElement;
+import org.jivesoftware.smackx.ox.element.SignElement;
+import org.jivesoftware.smackx.ox.element.SigncryptElement;
+import org.jivesoftware.smackx.ox.provider.OpenPgpContentElementProvider;
+import org.xmlpull.v1.XmlPullParserException;
+
+public class OpenPgpMessage {
+
+    enum State {
+        signcrypt,
+        sign,
+        crypt,
+        ;
+    }
+
+    private final String element;
+    private final State state;
+
+    private OpenPgpContentElement openPgpContentElement;
+
+    public OpenPgpMessage(State state, String content) {
+        this.element = content;
+        this.state = state;
+    }
+
+    public OpenPgpContentElement getOpenPgpContentElement() throws XmlPullParserException, IOException {
+        ensureOpenPgpContentElementSet();
+
+        return openPgpContentElement;
+    }
+
+    private void ensureOpenPgpContentElementSet() throws XmlPullParserException, IOException {
+        if (openPgpContentElement != null)
+            return;
+
+        openPgpContentElement = OpenPgpContentElementProvider.parseOpenPgpContentElement(element);
+        switch (state) {
+        case signcrypt:
+            if (!(openPgpContentElement instanceof SigncryptElement)) {
+                throw new IllegalStateException(
+                        "The used OpenPGP content element does not match the mode used in the raw OpenPGP message. Content element: "
+                                + openPgpContentElement.getElementName() + ". Mode: " + state);
+            }
+            break;
+        case sign:
+            if (!(openPgpContentElement instanceof SignElement)) {
+                throw new IllegalStateException(
+                        "The used OpenPGP content element does not match the mode used in the raw OpenPGP message. Content element: "
+                                + openPgpContentElement.getElementName() + ". Mode: " + state);
+            }
+            break;
+        case crypt:
+            if (!(openPgpContentElement instanceof CryptElement)) {
+                throw new IllegalStateException(
+                        "The used OpenPGP content element does not match the mode used in the raw OpenPGP message. Content element: "
+                                + openPgpContentElement.getElementName() + ". Mode: " + state);
+            }
+            break;
+        }
+    }
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/OpenPgpProvider.java

@@ -0,0 +1,25 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox;
+
+import java.io.InputStream;
+
+public interface OpenPgpProvider {
+
+    public OpenPgpMessage toOpenPgpMessage(InputStream is);
+
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/CryptElement.java

@@ -0,0 +1,44 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.element;
+
+import java.util.Date;
+import java.util.List;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jxmpp.jid.Jid;
+
+public class CryptElement extends EncryptedOpenPgpContentElement {
+
+    public static final String ELEMENT = "crypt";
+
+    public CryptElement(List<Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
+        super(to, rpad, timestamp, payload);
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public CharSequence toXML() {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/EncryptedOpenPgpContentElement.java

@@ -0,0 +1,41 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.element;
+
+import java.util.Date;
+import java.util.List;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+import org.jxmpp.jid.Jid;
+
+public abstract class EncryptedOpenPgpContentElement extends OpenPgpContentElement {
+
+    private final String rpad;
+
+    protected EncryptedOpenPgpContentElement(List<Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
+        super(to, timestamp, payload);
+        this.rpad = rpad;
+    }
+
+    @Override
+    protected void addCommonXml(XmlStringBuilder xml) {
+        super.addCommonXml(xml);
+
+        xml.openElement("rpad").escape(rpad).closeElement("rpad");
+    }
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/OpenPgpContentElement.java

@@ -0,0 +1,78 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.element;
+
+import java.util.Date;
+import java.util.List;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+import org.jxmpp.jid.Jid;
+import org.jxmpp.util.XmppDateTime;
+
+public abstract class OpenPgpContentElement implements ExtensionElement {
+
+    private final List<Jid> to;
+    private final Date timestamp;
+    private final List<ExtensionElement> payload;
+
+    private String timestampString;
+
+    protected OpenPgpContentElement(List<Jid> to, Date timestamp, List<ExtensionElement> payload) {
+        this.to = to;
+        this.timestamp = timestamp;
+        this.payload = payload;
+    }
+
+    public final List<Jid> getTo() {
+        return to;
+    }
+
+    public final Date getTimestamp() {
+        return timestamp;
+    }
+
+    public final List<ExtensionElement> getPayload() {
+        return payload;
+    }
+
+    @Override
+    public String getNamespace() {
+        return OpenPgpElement.NAMESPACE;
+    }
+
+    protected void ensureTimestampStringSet() {
+        if (timestampString != null) return;
+
+        timestampString = XmppDateTime.formatXEP0082Date(timestamp);
+    }
+
+    protected void addCommonXml(XmlStringBuilder xml) {
+        for (Jid toJid : to) {
+            xml.halfOpenElement("to").attribute("jid", toJid).closeEmptyElement();
+        }
+
+        ensureTimestampStringSet();
+        xml.halfOpenElement("time").attribute("stamp", timestampString).closeEmptyElement();
+
+        xml.openElement("payload");
+        for (ExtensionElement element : payload) {
+            xml.append(element.toXML());
+        }
+        xml.closeElement("payload");
+    }
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/OpenPgpElement.java

@@ -0,0 +1,85 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.element;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jivesoftware.smack.util.stringencoder.Base64;
+import org.jivesoftware.smackx.ox.OpenPgpManager;
+import org.jivesoftware.smackx.ox.OpenPgpMessage;
+import org.xmlpull.v1.XmlPullParserException;
+
+public class OpenPgpElement implements ExtensionElement {
+
+    public static final String ELEMENT = "openpgp";
+    public static final String NAMESPACE = "urn:xmpp:openpg:0";
+
+    private final String base64EncodedOpenPgpMessage;
+
+    private OpenPgpMessage openPgpMessage;
+
+    private byte[] openPgpMessageBytes;
+
+    private OpenPgpContentElement openPgpContentElement;
+
+    public OpenPgpElement(String base64EncodedOpenPgpMessage) {
+        this.base64EncodedOpenPgpMessage = base64EncodedOpenPgpMessage;
+    }
+
+    public OpenPgpMessage getOpenPgpMessage() {
+        if (openPgpMessage == null) {
+            ensureOpenPgpMessageBytesSet();
+            InputStream is = new ByteArrayInputStream(openPgpMessageBytes);
+            openPgpMessage = OpenPgpManager.toOpenPgpMessage(is);
+        }
+
+        return openPgpMessage;
+    }
+
+    public OpenPgpContentElement getContentElement() throws XmlPullParserException, IOException {
+        if (openPgpContentElement == null) {
+            openPgpContentElement = getOpenPgpMessage().getOpenPgpContentElement();
+        }
+
+        return openPgpContentElement;
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public String getNamespace() {
+        return NAMESPACE;
+    }
+
+    @Override
+    public CharSequence toXML() {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    private final void ensureOpenPgpMessageBytesSet() {
+        if (openPgpMessageBytes != null) return;
+
+        openPgpMessageBytes = Base64.decode(base64EncodedOpenPgpMessage);
+    }
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/SignElement.java

@@ -0,0 +1,44 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.element;
+
+import java.util.Date;
+import java.util.List;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jxmpp.jid.Jid;
+
+public class SignElement extends OpenPgpContentElement {
+
+    public SignElement(List<Jid> to, Date timestamp, List<ExtensionElement> payload) {
+        super(to, timestamp, payload);
+    }
+
+    public static final String ELEMENT = "sign";
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public CharSequence toXML() {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/SigncryptElement.java

@@ -0,0 +1,44 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.element;
+
+import java.util.Date;
+import java.util.List;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jxmpp.jid.Jid;
+
+public class SigncryptElement extends EncryptedOpenPgpContentElement {
+
+    public static final String ELEMENT = "signcrypt";
+
+    public SigncryptElement(List<Jid> to, String rpad, Date timestamp, List<ExtensionElement> payload) {
+        super(to, rpad, timestamp, payload);
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public CharSequence toXML() {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/element/package-info.java

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * XML elements for XEP-0373: OpenPGP for XMPP.
+ */
+package org.jivesoftware.smackx.ox.element;

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/package-info.java

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * Smack API for XEP-0373: OpenPGP for XMPP.
+ */
+package org.jivesoftware.smackx.ox;

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/provider/CryptElementProvider.java

@@ -0,0 +1,31 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.provider;
+
+import org.jivesoftware.smackx.ox.element.CryptElement;
+import org.xmlpull.v1.XmlPullParser;
+
+public class CryptElementProvider extends OpenPgpContentElementProvider<CryptElement> {
+
+    @Override
+    public CryptElement parse(XmlPullParser parser, int initialDepth) throws Exception {
+        OpenPgpContentElementData data = parseOpenPgpContentElementData(parser, initialDepth);
+
+        return new CryptElement(data.to, data.rpad, data.timestamp, data.payload);
+    }
+
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/provider/OpenPgpContentElementProvider.java

@@ -0,0 +1,69 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.provider;
+
+import java.io.IOException;
+import java.util.Date;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jivesoftware.smack.provider.ExtensionElementProvider;
+import org.jivesoftware.smack.util.PacketParserUtils;
+import org.jivesoftware.smackx.ox.element.OpenPgpContentElement;
+import org.jxmpp.jid.Jid;
+import org.xmlpull.v1.XmlPullParser;
+import org.xmlpull.v1.XmlPullParserException;
+
+public abstract class OpenPgpContentElementProvider<O extends OpenPgpContentElement> extends ExtensionElementProvider<O> {
+
+    public static OpenPgpContentElement parseOpenPgpContentElement(String element)
+            throws XmlPullParserException, IOException {
+        XmlPullParser parser = PacketParserUtils.getParserFor(element);
+        return parseOpenPgpContentElement(parser);
+    }
+
+    public static OpenPgpContentElement parseOpenPgpContentElement(XmlPullParser parser) {
+        return null;
+    }
+
+    @Override
+    public abstract O parse(XmlPullParser parser, int initialDepth) throws Exception;
+
+    protected static OpenPgpContentElementData parseOpenPgpContentElementData(XmlPullParser parser, int initialDepth) {
+        List<Jid> to = new LinkedList<>();
+        Date timestamp = null;
+        String rpad = null;
+        List<ExtensionElement> payload = new LinkedList<>();
+
+        return new OpenPgpContentElementData(to, timestamp, rpad, payload);
+    }
+
+    protected final static class OpenPgpContentElementData {
+        protected final List<Jid> to;
+        protected final Date timestamp;
+        protected final String rpad;
+        protected final List<ExtensionElement> payload;
+
+        private OpenPgpContentElementData(List<Jid> to, Date timestamp, String rpad, List<ExtensionElement> payload) {
+            this.to = to;
+            this.timestamp = timestamp;
+            this.rpad = rpad;
+            this.payload = payload;
+        }
+    }
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/provider/OpenPgpElementProvider.java

@@ -0,0 +1,31 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.provider;
+
+import org.jivesoftware.smack.provider.ExtensionElementProvider;
+import org.jivesoftware.smackx.ox.element.OpenPgpElement;
+import org.xmlpull.v1.XmlPullParser;
+
+public class OpenPgpElementProvider extends ExtensionElementProvider<OpenPgpElement> {
+
+    @Override
+    public OpenPgpElement parse(XmlPullParser parser, int initialDepth) throws Exception {
+        String base64EncodedOpenPgpMessage = parser.nextText();
+        return new OpenPgpElement(base64EncodedOpenPgpMessage);
+    }
+
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/provider/SignElementProvider.java

@@ -0,0 +1,40 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.provider;
+
+import java.util.logging.Logger;
+
+import org.jivesoftware.smack.util.StringUtils;
+import org.jivesoftware.smackx.ox.element.SignElement;
+import org.xmlpull.v1.XmlPullParser;
+
+public class SignElementProvider extends OpenPgpContentElementProvider<SignElement> {
+
+    private static final Logger LOGGER = Logger.getLogger(SigncryptElementProvider.class.getName());
+
+    @Override
+    public SignElement parse(XmlPullParser parser, int initialDepth) throws Exception {
+        OpenPgpContentElementData data = parseOpenPgpContentElementData(parser, initialDepth);
+
+        if (StringUtils.isNotEmpty(data.rpad)) {
+            LOGGER.warning("Ignoring rpad in XEP-0373 <sign/> element");
+        }
+
+        return new SignElement(data.to, data.timestamp, data.payload);
+    }
+
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/provider/SigncryptElementProvider.java

@@ -0,0 +1,30 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.ox.provider;
+
+import org.jivesoftware.smackx.ox.element.SigncryptElement;
+import org.xmlpull.v1.XmlPullParser;
+
+public class SigncryptElementProvider extends OpenPgpContentElementProvider<SigncryptElement> {
+
+    @Override
+    public SigncryptElement parse(XmlPullParser parser, int initialDepth) throws Exception {
+        OpenPgpContentElementData data = parseOpenPgpContentElementData(parser, initialDepth);
+        return new SigncryptElement(data.to, data.rpad, data.timestamp, data.payload);
+    }
+
+}

smack-openpgp/src/main/java/org/jivesoftware/smackx/ox/provider/package-info.java

@@ -0,0 +1,20 @@
+/**
+ *
+ * Copyright 2017 Florian Schmaus.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * Providers for XEP-0373: OpenPGP for XMPP.
+ */
+package org.jivesoftware.smackx.ox.provider;