Simplex Chat
SimpleX Chat: private and secure messenger without any user IDs (not even random)

        
            


    
        
    

    

    

    

    

    

    

    

    

    

    

    

    

    

    



    
        
        
        
        

        
        
            
                
                    
                        
                            
                        
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
                    
                
            
                
                    
                        
                            
                                
                                    
                                        
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                            Make a private connection
                        
                        
                    

                    
                
        





        Why privacy matters
        Preserving the privacy of your metadata — who you talk with — protects you from:
        
        Make sure your messenger can't access your data!
    



        Why SimpleX is unique

        
    


    
        
    
    

    

    
        
    
    

    

    
        
    
    

    

    
        
    
    

    






        Features

        
            
            
                
                    
                
                E2E-encrypted messages with markdown and editing
            
            
            
                
                    
                
                E2E-encryptedimages, videos and files
            
            
            
                
                    
                
                E2E-encrypted decentralized groups — only users know they exist
            
            
            
                
                    
                
                E2E-encrypted voice messages
            
            
            
                
                    
                
                Disappearing messages
            
            
            
                
                    
                
                E2E-encryptedaudio and video calls
            
            
            
                
                    
                
                Portable encrypted app storage — move profile to another device
            
            
            
                
                    
                
                Incognito mode —unique to SimpleX Chat
            
            
        
    



        What makes SimpleX private

        
    



        SimpleX Network
        Simplex Chat provides the best privacy by combining the advantages of P2P and federated networks.

        
            
                
                    
                
                
                    Unlike P2P networks
                    
                        All messages are sent via the servers, both providing better metadata privacy and reliable asynchronous message delivery, while avoiding many problems of P2P networks.
                        
    
    

                    
                
            

            

            
                
                    
                
                
                    Unlike federated networks
                    
                        SimpleX relay servers do NOT store user profiles, contacts and delivered messages, do NOT connect to each other, and there is NO servers directory.
                    
                
            

            

            
                
                    
                
                
                    SimpleX network
                    
                        servers provide unidirectional queues to connect the users, but they have no visibility of the network connection graph — only the users do.
                    
                
            

        
    






        Simplex explained

        
        

        

        
        

                
                    1. What users experience
                    
                        
                            You can create contacts and groups, and have two-way conversations, as in any other messenger.
                        
                        
                            How can it work with unidirectional queues and without user profile identifiers?
                        
                    
                

                
                    2. How does it work
                    
                        
                            For each connection you use two separate messaging queues to send and receive messages via different servers.
                        
                        
                            Servers only pass messages one way, without having the full picture of user's conversation or connections.
                        
                    
                

                
                    3. What servers see
                    
                        
                            The servers have separate Anonymous credentials for each queue, and do not know which users they belong to.
                        
                        
                            Users can further improve metadata privacy by using Tor to access servers, preventing corellation by IP address.
                        
                    
                

            
    







        Comparison with other protocols

        

        

        
                
                     Usually based on a phone number, in some cases on usernames
                     DNS-based addresses
                     Public key or some other globally unique ID
                     SimpleX relays cannot compromise e2e encryption. Verify security code to mitigate attack on out-of-band channel
                     If operator’s servers are compromised. Verify security code in Signal and some other apps to mitigate it
                     Does not protect users' metadata privacy
                     While P2P are distributed, they are not federated - they operate as a single network
                     P2P networks either have a central authority or the whole network can be compromised - see here
                
            
    






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    Content paddingAlso known as content padding, it is the process of adding data to the beginning or the end of a message prior to encryption. Padding conceals the actual message size from any eavesdroppers. SimpleX has several encryption layers, and prior to each encryption the content is padded to a fixed size.Wikipedia.Post-compromise securityAlso known as break-in recovery, it is the quality of the end-to-end encryption scheme allowing to recover security against a passive attacker who observes encrypted messages after compromising one (or both) of the parties. Also known as recovery from compromise or break-in recovery. Double-ratchet algorithm has this quality.Post-quantum cryptographyAny of the proposed cryptographic systems or algorithms that are thought to be secure against an attack by a quantum computer. It appears that as of 2023 there is no system or algorithm that is proven to be secure against such attacks, or even to be secure against attacks by massively parallel conventional computers, so a general recommendation is to use post-quantum cryptographic systems in combination with the traditional cryptographic systems.Wikipedia

        



        
        
        
    

