OMEMO IM: Simple & Secure Instant Messaging

• OMEMO Instant Messenger is a clean rebuild of the popular Android Jabber client "Conversations". It includes minor graphical and user friendly feature improvements consisting of:

  • A free to use community chat server "omemo.im" integrated into it's client.
  • A newer blue App color design with matching logo.
  • Easier to understand account creation wizard for ordinary users by simplifying description and removing technical jargon at startup.
  • Client State Indication is enabled by default to mimic other WhatsApp style Messengers that show when your contact was last seen online.
  • Removed Green Background on received messages option by default because it doesn't look cool.

• End-to-end encryption with OMEMO or OpenPGP
• Send and receive images as well as other kind of files
• Indication when your contact has read your message
• Intuitive UI that follows Android Design guidelines
• Pictures / Avatars for your Contacts
• Syncs with desktop client
• Conferences (with support for bookmarks)
• Address book integration
• Multiple accounts / unified inbox
• Very low impact on battery life

XMPP, like email, is a federated protocol, which means that there is not one company you can create an official XMPP account with. Instead there are hundreds, or even thousands, of providers out there. One of those providers is our very own omemo.im. If you don’t want to use omemo.im check our Servers to find another provider. Or maybe your university has one. Or you can run your own. Or ask a friend to run one. Once you've found one, you can use OMEMO IM to create an account. Just select register new account on server within the create account dialog.

Using your own domain not only gives you a more recognizable Jabber ID, it also gives you the flexibility to migrate your account between different XMPP providers. This is a good compromise between the responsibilities of having to operate your own server and the downsides of being dependent on a single provider.

• OMEMO works even when a contact is offline, and works with multiple devices. It also allows asynchronous file-transfer when the server has HTTP File Upload. However, OMEMO not widely support and is currently implemented only by a handful of clients.
• OpenPGP (XEP-0027) is a very old encryption method that has some advantages over OMEMO but should only be used by people who know what they are doing.

Before you continue reading you should note that the OpenPGP support in Conversations is experimental. This is not because it will make the app unstable but because the fundamental concepts of PGP aren't ready for widespread use. The way PGP works is that you trust Key IDs instead of JID's or email addresses. So in theory your contact list should consist of Public-Key-IDs instead of JID's. But of course no email or XMPP client out there implements these concepts. Plus PGP in the context of instant messaging has a couple of downsides: It is vulnerable to replay attacks and it is rather verbose.

To use OpenPGP you have to install the open source app OpenKeychain and then long press on the account in manage accounts and choose renew PGP announcement from the contextual menu.

OMEMO has two requirements: Your server and the server of your contact need to support PEP. Both of you can verify that individually by opening your account details and selecting Server info from the menu. The appearing table should list PEP as available. The second requirement is mutual presence subscription. You can verify that by opening the contact details and see if both check boxes Send presence updates and Receive presence updates are checked.

For conferences only OMEMO and OpenPGP are supported as encryption method..

OMEMO encryption works only in private (members only) conferences that are non-anonymous.

The server of all participants need to pass the OMEMO Compliance Test. In other words they either need to run version 18.01+ of ejabberd or have the omemo_all_access module installed on Prosody.

The owner of a conference can make a public conference private by going into the conference details and hit the settings button (the one with the gears) and select both private and members only.

If OMEMO is grayed out long pressing the lock icon will reveal some quick hints on why OMEMO is disabled.

Every participant has to announce their OpenPGP key (see answer above). If you would like to send encrypted messages to a conference you have to make sure that you have every participant's public key in your OpenKeychain. Right now there is no check in Conversations to ensure that. You have to take care of that yourself. Go to the conference details and touch every key id (The hexadecimal number below a contact). This will send you to OpenKeychain which will assist you on adding the key. This works best in very small conferences with contacts you are already using OpenPGP with. This feature is regarded experimental. Conversations is the only client that uses XEP-0027 with conferences. (The XEP neither specifically allows nor disallows this.)

Note: Future build versions of OMEMO Instant Messenger envisions to remove OpenPGP as well as Unencrypted and force the use of OMEMO E2EE only. Such that it is not possible to send an non-E2EE message from the client.

There are XMPP Clients available for all major platforms.

For your desktop computer we recommend that you use Gajim. You need to install the plugins OMEMO, HTTP Upload and URL image preview to get the best compatibility with Conversations. Plugins can be installed from within the app.

Zom or Chatsecure.

Make sure to have ANDROID_HOME point to your Android SDK. Use the Android SDK Manager to install missing dependencies.

git clone https://github.com/froghorn82/omemo-im.git
cd omemo-im
./gradlew assembleCompat or assembleFree