Session (software)

Session is a cross-platform end-to-end encrypted instant messaging application emphasizing user confidentiality and anonymity. Developed by The Oxen Project under the non-profit Oxen Privacy Tech Foundation, it employs a blockchain-based decentralized network for transmission. Users can send one-to-one and group messages, including various media types such as files, voice notes, images, and videos.

Session provides applications for various platforms, such as macOS, Windows, and Linux, along with mobile clients available on both iOS and Android.

Features
Session does not require a telephone number or email address for account creation. Instead, it utilizes a randomly generated 66-digit alphanumeric number for user identification. Communication between users, including messages, voice clips, photos, and files, is end-to-end encrypted using the Session protocol. Session uses the Loki blockchain network for transmissions. In 2021, an independent review by the third-party Quarkslab verified these claims.

Development
Session started as a fork of another messenger, Signal, aiming to build upon its foundation. However, concerns about the centralized structure of Signal Protocol and potential metadata collection led the team to deviate and create their own protocol, called "Session Protocol". This approach prioritized increased anonymity and decentralization. During development, the team encountered various challenges, leading to the necessity of abandoning or modifying many features.

Limitations
Session lacks support for two-factor authentication, and its underlying protocols are still in a developmental phase. Following the migration from the Signal Protocol to its internally developed protocol, forward secrecy and deniable authentication were not implemented.