Frequently Asked Questions
Conversations in Session are end-to-end encrypted, just as in most private messengers. However, when you use Session, the identities of the people communicating are also protected. Session keeps your communication private, secure, and anonymous.
When using Session, your messages are sent to their destinations through a decentralised onion routing network similar to Tor (with a few key differences), using a system we call onion requests. Onion requests protect user privacy by ensuring that no single server ever knows a message’s origin and destination. For more on this, check out What is an onion routing network? below. For more technical details, read our blog on onion requests.
Session’s code is open-source and can be independently audited at any time. Session is a project of the Oxen Privacy Tech Foundation, a not-for-profit organisation whose mission is to provide the world with better access to digital privacy technologies.
Session has also undergone a security audit by Quarkslab, the results of which can be found here.
Session encrypts your messages using the Session Protocol, a cutting-edge end-to-end encryption protocol built on libsodium, a highly-audited and widely trusted cryptographic library.
A technical description of the Session Protocol can be found in our technical deep-dive blog.
Session’s desktop, Android, and iOS clients have been audited by Quarkslab. The results of this audit can be found here.
Session allows users to encrypt their local Session database with a PIN code. With this feature turned on, your messages cannot be accessed without knowing your PIN code.
Because Session doesn’t have a central server storing information about your identity, restoring your account using the traditional username and password method is not possible. Your recovery phrase is a mnemonic seed which can be used to restore your existing Session ID to a new device.
Make sure you store it in a safe place!
Your recovery phrase is like the master key to your Session ID — it’s important to store it safely and securely, and to ensure that only you have access to it. Here are a few options for keeping your recovery phrase safe:
Write your recovery phrase on a piece of paper, then store it in a safe location.
Consider further securing your recovery phrase by splitting it into sections using a technique like Shamir’s Secret Sharing.
Remember — the order of the words in your recovery phrase is crucial. However you store it, ensure that you can reconstruct it in the same order in which it was provided.
At the startup screen, click Sign In and then Restore From Recovery Phrase.
Enter your recovery phrase into the text box, and select a new display name.
Your Session ID is recovered.
At the startup screen, tap Continue your Session.
Enter your recovery phrase into the text box.
Enter a new display name and tap Continue.
Select your preferred push notification setting and tap Continue.
Your Session ID is recovered.
Your recovery phrase is not currently able to restore your contacts or messages. For your security, your contacts and messages are stored locally, so they cannot be retrieved once you have deleted them.
You don’t need a mobile number or an email to make an account with Session. Your display name can be your real name, an alias, or anything else you like.
Session does not collect any geolocation data, metadata, or any other data about the device or network you are using. At launch, Session used proxy routing to ensure nobody can see who you’re messaging or the contents of those messages. Shortly after launch, Session moved to our onion routing system, which we call onion requests, for additional privacy protection. For more on Session’s secure message routing, check out What is an onion routing network? and What is proxy routing?
In messaging apps, metadata is the information created when you send a message — everything about the message besides the actual contents of the message itself. This can include information like your IP address, the IP addresses of your contacts, who your messages are sent to, and the time and date that messages are sent.
It’s impossible for Session to track users’ IP addresses because the app uses onion requests to send messages. Because Session doesn’t use central servers to route messages from person to person, we don’t know when you send messages, or who you send them to. Session lets you send messages — not metadata.
Session’s Android client has two options for notifications: background polling (slow mode), and Firebase Cloud Messaging (fast mode).
If you choose slow mode, the Session application runs in the background and periodically polls its swarm (see What is a swarm) for new messages. If a new message is found, it is presented to you as a local notification on your device.
If you choose fast mode, Session will use Google’s FCM push notification service to deliver push notifications to your device. This requires that your device IP address and unique push notification token are exposed to a Google operated push notification server. Additionally, you will expose your Session ID and unique push notification token to an OPTF operated push notification server, for the purpose of providing the actual notifications to the Google FCM server.
These exposures are fairly minimal, Google will likely already know your device’s IP address through telemetry data or other applications on your device using push notifications. Registration of your Session ID and unique push notification token to the OPTF push notification server is necessary for detection and signaling of new messages and is low impact as registration occurs using onion requests meaning your Session ID and push notification token are never tied to any real world identifier (such as your IP address).
When using fast mode neither Google nor the OPTF can see the contents of your messages, who you’re talking to, or exactly when messages are sent or received.
Session’s iOS client has two options for notifications: background polling (slow mode), and Apple Push Notification Service (APNs) (fast mode).
If you choose slow mode, the Session application runs in the background and periodically polls its swarm (see What is a swarm) for new messages. If a new message is found, it is presented to you as a notification on your device.
If you choose fast mode, Session will use APNs push notification service to deliver push notifications to your device. This requires your device IP address and unique push notification token are exposed to an Apple operated push notification server. Additionally, you will expose your Session ID and unique push notification token to an OPTF operated push notification server, for the purpose of providing notifications to the APNs server.
These exposures are fairly minimal, because Apple will likely already know your device’s IP address through telemetry data or other applications on your device using push notifications. Registration of your Session ID and unique push notification token to the OPTF push notification server is necessary for detection and signaling of new messages and is low impact as registration occurs using onion requests meaning your Session ID and push notification token are never tied to any real world identifier (such as your IP address).
When using fast mode neither Apple nor the OPTF can see the contents of your messages, who you’re talking to, or exactly when messages are sent or received.
Session now has an F-Droid repo for everyone who wants to avoid the Google Play Store.
Simply head to this address on an Android device with F-Droid installed to add the repo.
We don’t believe it does. From the very beginning of Session, and Oxen, we have been ready for regulatory hostility. Being built in Australia, one of the Five-Eyes intelligence alliance countries, meant accepting that hostile regulation was likely to come. But there’s a pretty simple reason as to why we chose to build here anyway: running from legislators isn’t a solution.
Rather than set up shop in Switzerland and hope that the regulatory environment never changes, we focused on developing technology that could be resistant to surveillance by governments (and everyone else too)
Decentralisation and metadata minimisation are the core of that ideal. The Session team is based in Australia, but Session has infrastructure all around the world. Over 1,500 community operated servers are currently routing Session messages for over 150,000 users, and the minimal amount of data that flows through them are inaccessible to the Session Team — we can’t be compelled to hand over information that we don’t have.
As Session is a project of the Oxen Privacy Tech Foundation, court orders in situations such as this would be targeted at the Foundation.
The OPTF would comply with lawful court orders. However, the OPTF could not reveal user identities; the Foundation simply does not have access to the data required to do so. Session ID creation does not use or require email addresses or phone numbers. Session IDs (which are public keys) are recorded, but there is no link between a public key and a person’s real identity, and due to Session’s decentralised network, there’s also no way to link a Session ID to a specific IP address.
The most the OPTF could provide, if compelled to do so, would be tangential information such as access logs for the getsession.org website or statistics collected by the Apple App Store or Google Play Store.
The Assistance and Access bill (also known as TOLA) was introduced in 2018 with the intention of allowing the federal government to compel Australian entities to give them backdoors into encryption protocols. The scope of TOLA extends far beyond encryption, but the bill has clauses that prevent the government from asking an application developer to insert a “systemic weakness” into their application. Our analysis of this provision indicates that any backdoor which would violate user privacy in Session would be beyond the scope of the Assistance and Access legislation.
As the entire Session codebase is open-source, authorities or malicious actors from any jurisdiction could create modified Session clients themselves, which could undermine user privacy. As the Assistance and Access bill does not allow the government to force us to push out a ‘systemic’ vulnerability, or prevent us from fixing such vulnerabilities, any modified client would not be pushed through the App Store or other official download channels. Instead, the attacker would need some method to directly inject the modified client onto a specific user’s device, something which we are not capable of doing.
Session’s developers do not have control over the Oxen Service Node network, the network used to route and store user encrypted messages. So long as associated codebases and software releases maintain integrity, we do not and will not have access to any privileged information which may undermine user privacy. And because our platform is open-source, anyone can independently verify that such integrity is maintained.
For a more in-depth overview of our perspective on the risks posed by TOLA, read our blog on the issue.
The Identify and Disrupt Bill was introduced at the end of 2020, adding three new classes of warrant for investigating online activity. While we staunchly oppose this expansion of the Australian government’s surveillance mandate, we don’t believe that the powers granted by this bill provide a threat to Session.
The bill has a focus on targeting individuals through their devices, accounts, and network activity. The dangers posed by this to Session are limited due to the following reasons
Session allows individuals to encrypt their local Session database with a PIN code, dampening the danger of device access compromising their Session instance
The Session team has no ability to access the accounts of Session users, as well as no ability to provide that access to authorities if requested
Session is built to minimise metadata leakage. Monitoring the network activity of an individual using Session would provide almost no information to authorities
Session is and will always be open source. Any changes to these key defenses would be public and visible to everyone
The Identify and Disrupt Bill provides no ability for the Australian government to force the Session team to modify Session to weaken the privacy and security of its users
On Android or iOS, tap the green plus button at the bottom of the main Messages screen, then tap the chat bubble icon that appears above the plus button. Paste or type your contact’s Session ID into the Session ID field, tap Next, then send your contact a message. Easy as that!
On desktop platforms, click New Session on the main Messages screen, paste or type your contact’s Session ID into the Session ID field, click Next, then send your contact a message.
Note: on desktop, you can also add a contact by clicking Add Contact in the Contacts section of the app.
One challenge with truly anonymous communications systems like Session is that sometimes you do need to verify the identity of the person you’re talking to! In cases like these, it’s best to use a secure secondary channel of communication to confirm with the other person that you’re both who you say you are.
Service Nodes are the community-operated nodes which make up the Oxen Network. There are currently over 1,000 nodes in the network. These Service Nodes are responsible for storing and routing your Session messages. You can read more about Service Nodes over at Service Node documentation.
When you send a message, it is sent to your recipient’s swarm. A swarm is a group of Oxen Service Nodes tasked with temporarily storing messages for retrieval by the recipient at a later point.
No, your messages are not stored on a blockchain. Messages are stored by swarms, and are deleted after a fixed amount of time (called the “time-to-live”, or TTL).
All of your messages are encrypted, and can only be decrypted using the private key which is stored locally on your device.
Session usernames are permanent alphanumeric names that can be purchased using the anonymous Oxen cryptocurrency and attached to a Session ID. If you have a Session username attached to your Session ID, others will be able to add you on Session using that name, instead of having to use your full Session ID. Usernames make adding contacts quick and convenient.
Session ID usernames are permanent names which can be purchased and attached to a Session ID. Once purchased and linked, you can give others your Session ID username and they can add you on Session using that name — much more convenient than dealing with a long, complicated Session ID.
Session nicknames are the names you can set for yourself in Session when you create a Session ID. Nicknames can be changed at any time, but you can’t use a nickname to add someone on Session.
Session can send files, images and other attachments up to 10MB in both person-to-person conversations and group chats. By default, Session uses the Oxen File Server for attachment sending and storage. The Oxen File Server is an open-source file server run by the Oxen Privacy Tech Foundation — the creators of Session. When you send an attachment, the file is symmetrically encrypted on the device and then sent to the Oxen File Server. To send the attachment to a friend, Session sends them an encrypted message containing the link, plus the decryption key for the file. This ensures that the Oxen File Server can never see the contents of files being uploaded to it.
Additionally, Session used proxy routing (soon to be onion routing) to hide users’ IP addresses when uploading or downloading attachments from the Oxen File Server. In future, you will be able to configure the Session app to use a custom file server, such as a self-hosted server or VPS (Virtual Private Server), if you would prefer not to use a file server hosted by the OPTF.
A swarm is a collection of 5 – 7 Service Nodes which are responsible for the storage of messages for a predefined range of Session IDs. Swarms ensure that your messages are replicated across multiple servers on the network so that if one Service Node goes offline, your messages are not lost. Swarms make Session’s decentralised network backend much more robust and fault-tolerant.
At the moment, Session uses onion requests. However, this solution only supports something called TCP (Transmission Control Protocol) traffic. TCP is a highly reliable protocol, but it’s also high-latency, meaning that video and voice chat is not viable.
Once Lokinet is implemented (see What is Lokinet? below), it will be possible to implement video and voice chat. Lokinet supports both TCP and UDP (User Datagram Protocol) traffic. UDP is a lightweight and connectionless protocol, making it ideal for broadcasting things like voice and video.
Closed groups are fully end-to-end encrypted group chats. Up to 100 people can participate in a closed group chat. Closed group messages are stored on Session’s decentralised network, without using any central server(s).
The short answer: open groups are not as private as person-to-person messages or closed groups.
The long answer: open groups are large public channels where Session users can congregate and discuss anything they want. Open groups, unlike other services in Session, are self-hosted and thus not fully decentralised. Someone has to run a server which stores the open group’s message history. Additionally, because open group servers can serve thousands of users, messages are only encrypted in transit to the server rather than being fully end-to-end encrypted.
For smaller group chats with a higher degree of privacy, users are encouraged to use closed groups. You can find out more about open groups and closed groups here.
An onion routing network is a network of nodes over which users can send anonymous encrypted messages. Onion networks encrypt messages with multiple layers of encryption, then send them through a number of nodes. Each node ‘unwraps’ (decrypts) a layer of encryption, meaning that no single node ever knows both the destination and origin of the message. Session uses onion routing to ensure that a server which receives a message never knows the IP address of the sender.
Session’s onion routing system, known as onion requests, uses Oxen‘s network of Oxen Service Nodes, which also power the $OXEN cryptocurrency. Check out Oxen.io to find more information on the tech behind Session’s onion routing.
Proxy routing was an interim routing solution which Session used at launch while we worked to implement onion requests. When proxy routing was in use, instead of connecting directly to an Oxen Service Node to send or receive messages, Session clients connected to a service node which then connects to a second service node on behalf of the Session client. The first service node then sends or requests messages from the second node on behalf of the mobile device.
This proxy routing system ensured that the client device’s IP address was never known by the service node which fetches or sends the messages. However, proxy routing did provide weaker privacy than the onion request system Session now uses. Proxy routing still provided a high level of security for minimising metadata leakage in the interim. The proxy routing system has now been replaced by onion requests.
Lokinet is a powerful onion router that is fast enough to handle real-time voice communications, making it a crucial part of our plan to add real-time end-to-end encrypted voice calls to Session without relying on central servers.
The Session team is hard at work fixing bugs and shoring up core messaging functionality, but once the app is working reliably, we’ll be moving on to Lokinet integration to bring voice calling functionality to Session. We’ll keep the community updated on our progress, so be sure to follow our Twitter to stay up to date!
For the best possible troubleshooting, you can include a debug log from your Session app. Simply navigate to Settings and tap/click 'Debug Log' to generate a log.
We welcome community feedback and feature suggestions! Send your suggestions to [email protected], and our team will take a look at them!
Oxen is the development team behind Session. Oxen is supported by the not-for-profit Oxen Privacy Tech Foundation. Oxen provides users with tools to interact online in an anonymous, decentralised, secure and private way. Oxen builds and maintains the Oxen stack of privacy and decentralisation tools, as well as building and supporting the Oxen blockchain and the $OXEN privacy token.
The Oxen Privacy Tech Foundation is Australia’s first privacy tech not-for-profit. The Foundation organises and supports a number of privacy tech initiatives around the world and right here in Australia. Oxen is the OPTF’s development initiative, building and maintaining privacy tools for individuals and organisations. The Oxen Network is the network of infrastructure that supports our privacy tools: Oxen Service Nodes, the Oxen blockchain, and all the accompanying tools and software.