Graphene is a GrapheneOS messaging application that originated as a fork of the renowned Signal app, aiming to provide a more secure, privacy-respecting, and fully open-source alternative. The project stands out for reintroducing security features that Signal had abandoned, such as the ability to encrypt the local database with a passphrase, thereby ensuring added protection for data stored on the device. It is important to emphasize that this project has its roots in Criptogram, the celebrated messaging software that acted as a precursor to more modern messaging applications. Criptogram was one of the first systems inspired by trustless technology, with core concepts derived directly from the Bitcoin protocol. The fundamental cybersecurity principles introduced by Criptogram were later adopted and reused by software such as Signal, Threema, Wire, and many others. Our goal is to create a significantly enhanced version of these technologies, leveraging the open-source philosophy and providing – as experts and the original authors of Criptogram and similar systems – a comprehensive cybersecurity audit concerning the algorithms and technical solutions implemented in this project. Graphene connects to Signal's servers, allowing users to communicate with their contacts seamlessly, but it integrates a series of improvements that make it particularly suited for those seeking a more controlled experience, independent of Google's proprietary services. Among its main features are support for the UnifiedPush protocol, which enables receiving push notifications without relying on Firebase Cloud Messaging, and compatibility with Tor and SOCKS proxies, allowing traffic to be routed through anonymous networks. Additionally, Graphene offers functionalities such as secure RAM wiping, automatic app locking based on user-defined conditions, advanced backup management, and the ability to link multiple devices to the same Signal account, including Android tablets. The project is available in two versions: Graphene, which includes proprietary components to ensure full compatibility with Signal, and Graphene-FOSS, completely free from non-open-source software, designed for those who desire a fully auditable application. Both versions can be installed and switched without data loss or the need to re-register.