How does Session messenger verify new accounts and prevent impersonation?
Executive summary
Session creates accounts without phone numbers or email by generating a random, long Account ID on the device; that Account ID is the primary identifier users share to connect, and Session explicitly does not perform centralized identity verification or require personal identifiers [1] [2] [3]. Because account creation is anonymous by design, Session shifts verification responsibility to out‑of‑band checks (sharing Account IDs, manual confirmation) and technical protections such as decentralised routing and metadata minimisation to reduce impersonation risk rather than using traditional identity proofs [4] [3] [5].
1. Account creation: anonymity by design, not an identity service
Session’s sign‑up model deliberately avoids phone numbers, emails, and central registries; a device generates a random, 66‑character (reported) Account ID that becomes the user’s identity within the network [1] [2] [3]. The platform’s public materials frame this as a privacy feature: you “never will” need to verify identity with a central authority when creating an account [2]. That design choice means Session does not and cannot offer the same kind of provider‑mediated identity verification that apps tied to phone numbers or email addresses do [2].
2. How users verify people: Account IDs and out‑of‑band checks
Because Session accounts are identified by Account IDs, the way to confirm you’re messaging the right person is to obtain and confirm that ID through other channels (for example, verbally, in person, or via a known contact method). The Session FAQ acknowledges the practical challenge: truly anonymous systems sometimes require users to verify identity, and Session relies on Account IDs and user‑side confirmation as the mechanism for adding contacts [4] [3].
3. Technical mitigations against impersonation and metadata leaks
Session reduces avenues for impersonation by minimising metadata, using onion routing and a decentralised network of nodes so messages and routing information are obscured, and by keeping account long‑term keys on devices rather than in a central store [3] [1] [6]. These measures make large‑scale correlation and attribution harder, which indirectly lowers certain impersonation vectors tied to metadata harvesting [3] [1].
4. Limitations exposed by experts and the community
Privacy reviewers and communities have criticised Session for lacking elements such as perfect forward secrecy (PFS) in earlier protocol versions and for device‑linking concerns that could allow account linkage if devices are compromised; Session has responded by designing a Protocol V2 that adds rotating per‑device keys, PFS, and other controls to strengthen account security and device management [7] [6] [8]. Critics have argued that technical protections do not replace explicit identity verification when users need high assurance of who they are speaking to [7].
5. What impersonation looks like on Session and what’s not addressed
Because anyone can create an Account ID at will, an adversary can create an account with any display name or avatar that mimics someone else; preventing that relies on users exchanging and validating Account IDs, not on Service‑level vetting [2] [3]. Available sources do not mention Session providing built‑in identity attestations, verified badges, SMS or email verification, or government ID checks — the product philosophy rejects those centralised verification paths [2] [3].
6. Recent protocol work aims to reduce device‑level impersonation risks
Session’s Protocol V2 introduces rotating key pairs per device and per account, improved linked device management, and PFS so that a compromised long‑term key or device cannot easily be used to impersonate or link new devices without notice [7] [6] [8]. The foundation frames these updates as closing gaps critics flagged, while noting no evidence yet of practical exploitation of those specific attacks on the live network [8].
7. Practical advice for users who need stronger identity guarantees
To avoid impersonation on Session, users should exchange Account IDs through trusted channels, confirm IDs in person or via an already‑trusted contact, and apply device‑level protections (secure backups, device locks). For contexts that demand institutionally verified identity (banking, legal services), Session’s model — intentionally anonymous and decentralised — is not designed to provide provider‑backed identity assurance [2] [4]. Available sources do not describe any built‑in reporting system tied to centralized identity takedown that would map anonymous IDs to real‑world identities [5].
Limitations and competing views: Session’s developers and community present anonymity and metadata resistance as the best defence against impersonation for privacy‑focused users [3] [1]; privacy‑tooling critics counter that absence of provider‑verified identity raises real risks in scenarios where verification is necessary, a gap Session is addressing technically with Protocol V2 but not philosophically by changing its anonymous sign‑up model [7] [6].