In late 2019, Loki Messenger was rebranded as Session. The transition was gradual. Early builds still referenced Loki internally while public branding shifted through the end of 2019 and into early 2020. By mid 2020, Session had fully replaced Loki Messenger across Android, iOS, Windows, macOS, and Linux.
Session originated under the Oxen Privacy Tech Foundation, which began in Australia. In October 2024, stewardship formally transferred to the Switzerland based Session Technology Foundation. In May 2025, Session completed a major infrastructure migration, moving away from the Oxen blockchain and onto a dedicated Session Network backed by an Ethereum compatible Layer 2 token.
Session is not designed to compete with mainstream messengers on polish or speed. It is designed to remove metadata at the network level, even when that decision introduces friction.
Decentralized Message Routing
Session does not use central servers. Messages are routed through a decentralized network of community operated servers called Service Nodes. These nodes are run by independent operators who stake cryptocurrency to participate in the network.
When you send a message, it is encrypted on your device and routed through a three hop onion path. Each hop is a randomly selected Service Node. No single node sees both the sender and the recipient. One node sees your IP address but not the destination. Another sees the destination but not your IP address. The middle node sees neither.
This design is inspired by Tor but optimized for asynchronous messaging rather than web browsing.
Messages are temporarily stored in small groups of nodes known as swarms. Each swarm contains roughly five to seven Service Nodes. If the recipient is offline, the encrypted message remains in the swarm until it is retrieved. Messages automatically expire after fourteen days.
There is no global inbox. There is no central database. There is no single operator with visibility into who is talking to whom.
Identity Without Registration
Session accounts are created entirely on device. When you install the app, it generates a long term X25519 public and private key pair. Your Session ID is simply the public key encoded as a 66 character string.
There is no phone number requirement. There is no email address. There is no contact discovery service. If someone does not already have your Session ID, they cannot find you.
This avoids the identity binding model used by Signal, WhatsApp, and Telegram, where phone numbers act as permanent identifiers.
Encryption Model and Protocol V1
Session uses end to end encryption built on libsodium. Messages are encrypted using X25519 for key exchange and ED25519 for signatures via crypto_box_sealed.
Earlier versions of Session inherited parts of the Signal protocol. Over time, features that conflicted with decentralization were removed. One of those was perfect forward secrecy.
Under Session Protocol V1, messages were encrypted using a long term identity key rather than a ratcheting key schedule. This simplified multi device support and offline message delivery across a decentralized network. It also introduced a real limitation. If a private key were compromised, stored messages within the fourteen day retention window could be decrypted.
This was a deliberate design tradeoff, not an accidental omission.
Protocol V2 Announcement
In December 2025, Session publicly announced Session Protocol V2. This new protocol restores perfect forward secrecy through rotating per device keys and introduces post quantum key exchange mechanisms based on lattice cryptography.
Protocol V2 is designed to correct the primary cryptographic weakness of Protocol V1 while preserving decentralization and metadata resistance. It does not reintroduce phone numbers, central directories, or trusted servers.
Metadata Resistance
Session’s strongest property is metadata minimisation. There is no registration database. There is no phone number graph. There is no contact list uploaded to a server. There is no central authority capable of reconstructing social relationships.
Each Service Node only sees encrypted payloads and partial routing information. Swarms store ciphertext only. Without private keys, node operators cannot read messages or determine who is communicating.
This distinguishes Session from federated systems like Matrix, where server operators can log metadata, and from centralized systems like Signal, where a single provider controls routing infrastructure.
Limitations and Threat Model
Session does have limitations. Onion routing adds latency. Large attachments are slower to deliver than on centralized platforms. Push notifications still rely on platform notification services.
Session is not designed to defeat a global passive adversary. A sufficiently powerful observer monitoring large portions of the network could attempt traffic correlation. The economic cost of operating Service Nodes raises the barrier to such attacks but does not eliminate the risk.
These constraints are documented openly. Session does not claim perfect anonymity.
Governance and Incentives
Service Nodes are permissionless but economically gated. Operating a node requires staking Session tokens. As of 2025, the stake requirement is 25,000 SESH per node. In return, operators earn rewards for storing and routing messages.
Development funding comes from staking economics, foundation grants, and optional paid features. Core messaging remains free. Paid features include usernames, larger groups, and enhanced backups. Fees are recycled into the ecosystem rather than monetized through data extraction.
What Session Is Becoming
Session is evolving from a privacy focused messenger into a broader decentralized communications stack. Protocol V2 introduces forward secrecy and post quantum resilience. Planned Lokinet integration aims to reduce latency and enable voice and video calls over anonymized paths.
The May 2025 launch of the Session Network unified the app, network, and token under a single architecture. This removed legacy dependencies and enabled faster protocol development.
Bottom Line
Session does not optimize for convenience. It optimizes for anonymity.
If you want frictionless onboarding tied to a phone number, Session is the wrong tool. If you want a messenger that can function without knowing who you are, where you live, or who you talk to, Session remains one of the few projects willing to accept the engineering cost of that decision.
Blackout VPN exists because privacy is a right. Your first name is too much information for us.
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FAQ
Does Session require a phone number or email address
No. Session accounts are created on device and identified only by a cryptographic public key.
How long are messages stored on the network
Encrypted messages are stored in swarms for up to fourteen days if the recipient is offline.
Is Session fully decentralized
Message routing and storage are decentralized. Some supporting services like push notifications still rely on platform infrastructure.
What changed with Protocol V2
Protocol V2 restores perfect forward secrecy and adds post quantum key exchange while preserving decentralization.
Is Session anonymous against all adversaries
No. Session reduces metadata exposure but does not claim to defeat a global passive adversary.