Security

Why SeTalk is safer

In plain words: what happens to a message, who can learn what, and what no app can protect. Every technical claim links to its source. SeTalk is made for professional discretion, such as business confidentiality and trade secrets. SeTalk is built on SimpleX Chat v7.0.3; where something depends on SeTalk's own setup and hasn't been tested yet, we mark it planned.

The path of a message

From your phone to your contact's, in four steps.

Only two phones can read the message: yours and your contact's. Everything in between carries a sealed package.¹

1 · On your phone
Locked before it leaves
Your phone locks the message with a key that only your contact's phone has.
Learn more
End-to-end encryption with a double ratchet: every message gets a new key, so one leaked key doesn't open the others. In direct conversations it adds a quantum-resistant layer (sntrup761) on top of standard encryption.²³
2 · On the way
Carried, never opened
The sealed package travels through SeTalk servers. They pass it on, but they can't open it.¹
Learn more
planned The app uses "private message routing" by default: a first server forwards the package, so the server that holds it doesn't see your IP address. With SeTalk running both servers, the content and who you talk to stay protected from people watching the network, but not from us: in theory, an operator of both servers could match the timing of packages going in and out. People watching the network can still see that you use the service, and when. We'll confirm it once our servers are live. The content stays locked either way.⁴⁵
3 · Waiting room
Waits sealed, with no name
The package waits in a queue that isn't linked to any person, until your contact's phone picks it up.⁶
Learn more
Each direction of each conversation has its own queue with its own credentials. There is no user ID. planned On SeTalk servers, messages are removed once delivered, or after 21 days at most, the same as SimpleX's own servers. We'll confirm this once our servers are live.⁶⁷
4 · Your contact's phone
Opened by one phone only
Your contact's phone unlocks the package and the message becomes readable again.
Learn more
Your keys are created and kept on your phone and don't pass through our servers. To be sure you're talking to the right person, compare the security code with your contact in person or through another channel.⁸

Who learns what

What each side can know about you.

The same five questions, first for SeTalk and then for a typical messenger that signs you up with a phone number.

Doesn't learn
Learns a little
Learns

With SeTalk
Question	You	Your contact	SeTalk servers	Your carrier or network	Google	Payment
What you write	Yours	Yesthey're meant to	Noonly sealed packages¹	No	No	No
Who talks to whom	Yours	Yesonly their own conversations	Not by nameonly queues, with no names attached; timing could in theory be matched, since SeTalk runs the servers⁶⁵	That you use SeTalknot who you talk to	Nonotifications don't go through Google⁹	No
Phone number or email	Yours	Nounless you tell them	Nonever asked¹⁰	Already has itnot from SeTalk	Your Google accountonly if you install from Google Play; a direct APK is planned, coming soon⁵	No
Your address book	Yours	No	Nothe app doesn't ask for access to it¹¹	No	Nonot through SeTalk	No
That you paid	Yours	No	Yes, SeTalk's account service sees an invoice for your username, with no real name; the message servers don't¹⁰	No	Nothere's no payment in the app¹⁰	Hidden on the blockchainMonero doesn't show who paid; the exchange where you bought it knows you bought Monero¹²

With a typical messenger
Question	You	Your contact	The messenger's servers	Your carrier or network	Google	Payment
What you write	Yours	Yes	Dependsmany encrypt end to end; some don't, or only in some chats	No	Dependsif backups go to your Google account	—
Who talks to whom	Yours	Yes	Usuallyaccounts are tied to phone numbers	That you use it	Often a littlenotifications usually go through Google's push service	—
Phone number or email	Yours	Usuallyyour number is how they find you	Yesit's your account	Yesit also delivers the SMS sign-up code	Your Google account	—
Your address book	Yours	No	Oftenmany apps upload or check it to find contacts	No	Dependsif your contacts sync to Google	—
That you paid	—	—	Usually freepaid for in other ways, depending on the service	—	—	—

A general picture; each service differs. For named apps, with a source and date for every cell, see Compare.

The reasons

Why it's safer, one reason at a time.

Each reason links to its source. Facts about SimpleX are checked for the version SeTalk is built on (v7.0.3).

No phone number, no email
You sign up with a username, a password and an authenticator app. There's nothing that ties the account to your name.
What SeTalk keeps about you¹⁰
No user ID on the servers
Servers see separate queues, not people. Not even a random number links your conversations together.
Source: SimpleX privacy policy (v7.0.3)⁶⁸
Built to resist future quantum computers
Direct conversations add a layer designed to resist them, on by default. Group chats don't have it yet.
Source: SimpleX v5.6 and v5.7 notes³²
Notifications don't go through Google
The app checks for messages itself, in the background. Google's push service isn't used.
Source: SimpleX app notifications (v7.0.3)⁹
Paid in Monero
No card, no bank statement. The blockchain doesn't show who paid, who received or how much.
Why we only accept Monero¹²
App code to be published, audited foundation
The app's code will be published under AGPL-3.0, together with the app. Our messaging servers run SimpleX's server code without modification. Trail of Bits reviewed the upstream SimpleX project in 2022 and 2024. Those are audits of SimpleX, not of SeTalk. Our account service isn't public, so what it keeps is listed in the account record.
SimpleX server code · Source: SimpleX security audits · What SeTalk keeps about you¹³¹⁴¹⁵¹⁰
Messages don't pile up on servers planned
Removed once delivered, or after 21 days at most. That's how SimpleX's own servers work; we'll confirm it on ours once they're live.
Source: SimpleX server settings⁷⁶

Honest limits

What no app protects, not even SeTalk.

Encryption protects the message on the way. It can't protect a phone that's in the wrong hands or a person who shares what you sent.

A compromised phone

Spyware on a phone reads what's on its screen, before any encryption.

Keep the system updated and install apps only from trusted sources.

An unlocked phone

Anyone holding your unlocked phone can open your conversations.

Lock the screen and set an app passcode in SeTalk.⁸

The person on the other side

Your contact can take a screenshot, forward or show the message.

Use disappearing messages, and think about who's in each group.⁸

The wrong person

An invitation sent to the wrong person connects you to the wrong person.

Send invitations only directly, and verify each contact through another channel.⁸

Go deeper

Check it for yourself.

Threat modelWhat SeTalk is designed to protect against, and what it isn't.

Audits (upstream)Trail of Bits reviews of SimpleX, 2022 and 2024.¹⁵

App source codeThe SeTalk app's code, to be published under AGPL-3.0, together with the app. Our servers run SimpleX's code, unmodified.¹³¹⁴

Why SeTalk is safer

From your phone to your contact's, in four steps.

Locked before it leaves

Carried, never opened

Waits sealed, with no name

Opened by one phone only

What each side can know about you.

Why it's safer, one reason at a time.

No phone number, no email

No user ID on the servers

Built to resist future quantum computers

Notifications don't go through Google

Paid in Monero

App code to be published, audited foundation