Signal Protocol
Signal’s own libsignal (PQXDH + Double Ratchet): a fresh key for every message, post-quantum key agreement.
Kryptos
Your messages become secret code that only your friend can read — in any messenger, even SMS.
No accounts, no servers, no setup — just you, your friend, and keys that never leave your phones.
iOS: sign the .ipa with your own certificate (e.g. Feather). Android: allow installs from unknown sources.
SHA-256 checksums
.ipa 675739dc5598966b56fc7ee2c68ddae719c4af020267a1885d0aeb8c5cacac0d
.apk 846fb9ca745f28e5cc1b7bd565ad0cee0d639111c8400538f2d0c77842c1b7ce
How it works
1
Write & encrypt
Type a message in Kryptos or straight on its keyboard — one tap turns it into code.
2
Send it anywhere
Paste the code into any chat: WhatsApp, Telegram, iMessage, SMS. To everyone else it's just random characters.
3
It decrypts on screen
Your friend's Kryptos shows the real text right over the code — or decrypts it in the keyboard or with one tap in the app.
Features
Any messenger
Encrypt in Kryptos, paste the code into WhatsApp, Telegram, iMessage or SMS — the messenger only ever sees ciphertext.
Fully offline
No networking code at all. Keys are generated on-device and stay in the Keychain / Keystore.
Decryption right on your screen
On Android, Kryptos can spot its messages in any app and lay the decrypted text right on top of them — live, as you scroll the chat. It only works for your contacts and never while Kryptos is locked. On iOS, a copied message opens already decrypted.
Steganography
Hide an encrypted message inside a photo, or disguise it as a run of ordinary words.
Keyboard
Encrypts and decrypts right in the text field of any app — no switching around.
App lock & clipboard
Face ID / biometrics, content hidden in the app switcher, clipboard auto-clear.
Panic PIN
A separate PIN that, instead of unlocking, instantly wipes all keys, chats and contacts (Android).
Requirements
iOS
iOS 17 or later. The .ipa is unsigned — sign it with your own certificate (e.g. Feather).
Android
Android 8.0 or later. Self-signed .apk — allow installs from unknown sources.
Network
Not used. The app works fully offline.
Languages
Russian and English — follows the system language.