Zero-Knowledge Architecture in Afina: How Your Profiles Stay Private
Afina is the only top-tier anti-detect browser that encrypts profile data client-side. Here's the threat model and how the crypto actually works.
Anti-detect browsers store the most sensitive data on the internet — your cookies. A single rotated session for a high-tier ad account is worth four-figure dollars. So the question of who can read your profile data should be answered with a single word: nobody but you.
The default model is bad
Every major anti-detect browser other than Afina stores profile data — cookies, IndexedDB, localStorage, fingerprint config — encrypted at rest on the vendor's servers with keys held by the vendor. That gives you these threats:
- Rogue staff — a database admin can decrypt any profile
- Hot DB compromise — if the operational key is exfiltrated, all profiles leak
- Legal requests — the vendor can be ordered to hand over your cookies
- Vendor pivot — a sold/acquired company can change the policy unilaterally
What zero-knowledge actually means
In a zero-knowledge architecture, encryption keys are derived on the client from your master password (Argon2id with a per-user salt), and the server only ever sees:
- A password verifier (not the password)
- Encrypted profile blobs (ciphertext + IV + tag)
- Wrapped keys for team sharing (each teammate has a curve25519 keypair; the profile's symmetric key is wrapped to each teammate's public key)
When you open a profile, the client decrypts locally. The server cannot read the cookies. Not "won't" — cannot.
How Afina implements it
Afina uses:
- Argon2id (m=256MB, t=3, p=4) for password-to-key derivation
- XChaCha20-Poly1305 for profile blob encryption
- X25519 for key wrapping in team sharing
- Ed25519 for signed audit log entries (so the audit log cannot be tampered server-side either)
Profile data is encrypted before it leaves the client. Sync is just ciphertext replication.
Team sharing without compromise
Sharing a profile with a teammate works like this:
- You retrieve their X25519 public key from the server (signed by their account at sign-up).
- You wrap the profile's symmetric key with their public key.
- The wrapped key is pushed to the server.
To revoke access, you rotate the profile key and re-wrap to the remaining teammates. The revoked teammate's wrapped key is deleted; even if they retained an old copy, the new ciphertext is unreadable.
What it costs
Two things:
- No "I forgot my password" recovery — there is nothing the vendor can do. Afina offers a Shamir-split escrow option (e.g. 3-of-5 admins) so teams can recover; solo accounts are responsible for their backup.
- Slightly slower first decrypt — the Argon2id step adds about 600ms to first profile open. Subsequent opens cache the derived key in memory.
Why this matters for compliance
If you operate in jurisdictions where customer data confidentiality is regulated (EU GDPR, UK DPA, US state laws), being able to demonstrate that even the vendor cannot read customer data is a defensible posture. With a non-ZK anti-detect, your data is technically accessible to the vendor — which means it's accessible to whoever the vendor's accessible to.
Bottom line
Zero-knowledge is now table stakes for password managers and is becoming table stakes for cloud storage. There's no good reason for anti-detect browsers — which hold cookies more valuable than passwords — to lag behind. Afina got there first; competitors will catch up; until they do, the choice is obvious.