What is cMix?

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All messaging between users in the xx network is sent through cMix, a mixed network (mixnet) anonymous communications protocol. The cMix protocol protects each xx messenger user's unique metadata—the who, what, when, where, and how of any message or activity in the app. xx messenger unlinks sender and recipient data and protects against traffic-analysis attacks that undermine many other privacy approaches found in onion routing, proxies, and other mixnets.

Surveillance and data privacy are significant concerns for all internet users. The services built on cMix provide a robust solution with privacy integrated in its design–it is impossible to track xx messenger users. With xx cMix, all transactions are mixed in batches called “anonymity sets” that are processed as a group. This mixing shreds all metadata and prevents third parties from analyzing activity patterns and connecting message senders to message recipients. The cMix protocol provides unprecedented consumer protection–no third party can monitor your behaviors and market to you as such. Using xx cMix allows users to interact and transact in an environment that is guaranteed to be protected and private. See below for a description of how this works. Please note: Elixxir was the prior branding name for this part of the xx network.

Message Mixing System Comic


Unlike other communications systems and mixnets that claim to provide anonymous communication, cMix guarantees complete privacy and no sharing of identifiable metadata in its design. This protects users from any privacy threats that retailers or government actors might pose. It also prevents discrimination toward users based on their geographic locations.

Other mixnet designs suffer from high latency, in part, due to the need for realtime public-key operations. cMix, through a precomputation process, eliminates the need for expensive realtime public-key operations at the senders, recipients, and nodes. Precomputation decreases real-time cryptographic latency and lowers computational costs for clients, significantly improving the real-time performance of cMix as it only needs to perform a few modular multiplications. Consequently, cMix is the first mixing suitable for low-latency chats on lightweight devices.

The xx cMix protocol provides the base for anonymous communication, but there are many other protocols built on top of it to provide a seamless user experience inside xx messenger:

  • End-to-End Encryption (E2EE)
  • User Discovery
  • Anonymous Message Return
  • Insert others here

Other Resources