Encrypted messaging

A private messenger without the catch.

Your identity is three words, made on your phone and known to nobody else.

No phone numberNo emailNo account

Android. Free and open source, GPL-3.0.

9:41···
Marina
wren·velvet·march
Verified
3
Vouches
2y
Chatting
Keys verified in person · Apr 2
can't sleep. the rain is loud here
sunny and loud here
Message
01 · The problem

Every private messenger asks for something.

Encrypting the words is the easy part. What gets collected around them is where privacy quietly goes.

The usual catch

Your phone number

In most countries a number is tied to an identity document. Handing one over to sign up undoes much of what the encryption was for.

The usual catch

Your address book

Uploading your contacts to find friends hands over your social graph: who you know, and who they know.

The usual catch

Push notifications

Waking your phone through Google's servers tells a third party who is messaging you, and when.

Kryfo

None of them

No number, no address book, no push service, and no directory anyone can search. There is nothing to hand over, because nothing is collected.

02 · How it works

Serious cryptography, explained in plain words.

The Signal Protocol underneath, the same double ratchet Signal uses, through an open-source implementation. Tor and Nostr relays for delivery. And an interface that tells you what it is doing instead of assuming you already know.

Three words

Your name is made on your phone.

Nothing is registered anywhere. You get three words nobody can trace back to you, and a face you pick. That is the whole account, and it takes about a minute.

9:4102 / 07
This is you

Made on this phone. Nothing is sent anywhere.

wren·velvet·march
Nobody can look this up. You share it, or you don't.
Continue
You choose the route

It tells you what each route costs.

Slower and hidden from everyone, or faster and seen by a relay. Most apps decide this for you and never mention it. Kryfo puts the trade-off in plain words and lets you pick.

9:4104 / 07
How your messages travel.

You can change this any time.

DEFAULT
Onion
Slower to start. Your address stays hidden from everyone, including us.
IP HIDDEN both sides
Fast
Quicker. Our relay sees when you connect.
IP HIDDEN from contacts
Keep onion →
No strangers

Nobody reaches you unless you let them.

There is no search and no directory, so you cannot be found by accident. People come in through a code you show them, a link you send, or an introduction from someone you already trust.

9:41Requests
Sarah
Wants to connect
Introduced by Tom
Nadia
Wants to connect
Looks safe · nothing suspicious in their first message
Tom
Wants to connect
Name matches your contact Tom
Rooms that end

Some conversations should disappear.

A burner room expires and takes everything with it, on every phone in it. You join under a name that exists only inside that room, so leaving ends the connection completely.

9:41burns in 18h
This room and everything in it disappears in 18 hours
did the scans come through?
all of them. thanks
good. see you thursday
Screenshots don't work in here
03 · Useful alone

Useful before anyone else joins.

A messenger is only worth something once your friends are on it. So Kryfo comes with four tools that need nobody else and no internet. Everything happens on your phone.

New in version 0.3.0.

What a photo gives away

See what a photo says about you.

Pick a photo and Kryfo shows what is hidden inside it: where it was taken, drawn on a map the app carries itself, on what phone, and when. Then it makes a clean copy with all of it gone, and checks the copy before handing it over.

9:41Tools
What this photo knows

Read on this phone. The photo went nowhere.

Near Neukölln, Berlin · accurate to about 5 metres
Samsung Galaxy A12
The phone that took it
Sunday 14 September, 18:42
To the second
23 more fields
Lens, software, orientation
Remove all of it
Tool

Clean any photo or video

Share one to Kryfo from your gallery and get a clean copy back. Location, phone and time are gone, and the picture itself stays exactly the same.

Tool

Private QR codes

Links, Wi-Fi, contacts, text and more. Made on your phone, so no website sees your Wi-Fi password, and no link gets wrapped in a tracker.

Tool

Lock a file with a password

Send it anywhere, by email or on a USB stick. It opens in Kryfo, or on any computer with the free tool age.

04 · The other side

What it isn't.

Privacy software has a habit of promising more than it can keep. So here is the part most sites leave out.

It hasn't been audited yet

No outside security firm has examined Kryfo. The cryptography it builds on is well studied, but the way this app uses it has not been independently reviewed by anyone. Work is underway to change that, and the report will be published in full, whatever it says.

It is early

Kryfo works, and it is used every day. But it is young, features are still landing, and things change between releases. If you find something broken, the issue tracker is open and every report gets read.

05 · Get it

Free, open, and nothing to sign up for.

Android will warn you about installing outside the Play Store. That is expected. Allow it for your browser or files app, then open the file again.

Check what you installed

Every build Kryfo signs carries the same key. If you install an Android package from anywhere other than F-Droid, you can confirm it came from us before trusting it.

SHA-256 signing fingerprint 10:92:8A:61:64:2C:5C:C4:71:A9:98:69:E2:EA:4E:2D:4D:70:02:6E:79:7D:FB:A4:8C:0F:30:6B:5B:34:73:DB

How to check a download, on a computer or on the phone: kryfo.app/download.

F-Droid signs its own builds with F-Droid's key, not this one, which is why a package installed from there will not match. That is expected, and it is the reason a build from F-Droid cannot update one installed by hand.