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Security & Custody

Kryptos

Kryptos is an open-source iOS and Android application with a system keyboard for encrypting text in messaging apps and decrypting received ciphertext. Its documented workflow uses the Signal Protocol, works offline, and also supports shared-password encryption and PGP.

Explore the practical guide ↓

Independent OpenViST project profile, based on linked sources.

Kryptos — OpenViST project profile in Security & Custody.
OpenViST project illustration. See the linked sources for product details.
Understand the project

Practical overview

When it fits

Use Kryptos when you want to encrypt message text from a mobile keyboard and send the ciphertext through an existing messenger or SMS. It is especially relevant when both participants can exchange Kryptos keys or agree on a shared password.

Who it is for

  • Mobile users who want to send encrypted text through messaging apps or SMS.
  • People exchanging messages with another Kryptos user across iOS and Android.
  • Users who need an encryption layer in a messenger where end-to-end encryption is not enabled by default.

Documented uses

  • Encrypt text before sending it from a messenger.
  • Share keys with a recipient and add their key as a contact.
  • Decrypt received ciphertext in the app or keyboard.
  • On Android, display decrypted messages over a messenger chat after enabling the feature and granting accessibility access.
Before you choose

Requirements & limits

The stated requirements are iOS 17 or later and Android 8.0 (API 26) or later; Android supports arm64-v8a and armeabi-v7a. Android installation is documented through F-Droid or a direct APK. The documented iOS IPA is unsigned and requires user signing.

  • Signal Protocol exchanges require both people to share keys and add each other as contacts; a shared password is an alternative that avoids key exchange.
  • Android on-screen decryption requires enabling the feature and granting accessibility access; it is disabled by default.
  • The iOS installation route involves signing the unsigned IPA, and AltStore or SideStore signatures are stated to last seven days before renewal.
  • The project identifies its license as AGPL-3.0 and its primary repository language as Swift.

Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.

Source-based practical guide

Exchange an encrypted message using recipient keys

Set up a recipient key and send ciphertext through a messenger.

Before you start

  • Kryptos installed on supported iOS or Android devices.
  • The recipient also uses Kryptos.
  • A way to share the key, such as a QR code or copied text.

Steps

  1. In Chats, share your key using its QR code or copy and send the key.

  2. Add the recipient’s key using Add contact.

  3. Write a message in Kryptos or a messenger using the Kryptos keyboard, then encrypt it.

  4. Send the ciphertext through the messenger.

  5. The recipient decrypts it in the app or keyboard; on Android, on-screen decryption is available after enabling it and granting accessibility access.

Expected outcome

The recipient can decrypt the message using Kryptos.

Guide limitations

  • Android on-screen decryption requires enabling the feature and granting accessibility access.
  • On iPhone, copy the ciphertext to display the decrypted text in the keyboard.
Documentation 1 ↗
Evidence and transparency

Sources & review

Official repository ↗
Source record details
Source availability
Active
Sources checked
14 October 2026
Original website title
swisslite/Kryptos · Official homepage title · retained in its source language
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