---
title: > 
    Build: Encryption Support
description: How to setup OMEMO encryption in CProof
sidebar:
  order: 2
---

## Building with OMEMO support

</br>
<a href="https://conversations.im/omemo/" target="_blank" rel="noopener noreferrer">
  OMEMO
</a>
is an XMPP Extension Protocol (XEP) for secure multi-client end-to-end encryption. It is an open standard based on a Double Ratchet and PEP.

CProof supports OMEMO only if you build from current git master. Support is planned for the 0.7.0 release.

If you have _libsignal-protocol-c_ installed, support will be included by default. To force the build to fail if support cannot be included, configure with the following:

```bash
./configure --enable-omemo
```

Supported _libsignal-protocol-c_ versions are 2.3.1, and 2.3.2.

## Building with PGP support

CProof uses the <a href="https://www.gnupg.org/%28es%29/related_software/gpgme/index.html" target="_blank" rel="noopener noreferrer">GPGME library</a> to support PGP encryption. You will need the _libgpgme-dev_ or equivalent installed. If the package is installed PGP support will be included automatically. To force the build to fail if support cannot be included, configure with the following:

```bash
./configure --enable-pgp
```

## Building with OTR support

Off The Record (OTR) messaging is a form of secure messaging, it includes encryption, authentication between users, deniability and perfect forward secrecy.

An overview and many useful resources can be found at the <a href="https://otr.cypherpunks.ca/" target="_blank" rel="noopener noreferrer">OTR site</a>.

If you have _libotr-dev_ installed, support will be included by default. To force the build to fail if support cannot be included, configure with the following:

```bash
./configure --enable-otr
```

Supported _libotr_ versions are 3.2.x, and 4.0.x.

On most distributions there is simply a _libotr-dev_ package you need to install first.

On Cygwin you will need to install the _libgcrypt-devel_ package first. Secondly you will need _libotr-devel_ package which is not currently in the official repositories. You can install it from the <a href="https://sourceware.org/cygwinports/" target="_blank" rel="noopener noreferrer">Cygwin Ports project</a>.
