CryptKB

CryptKB helps you encrypt message text before it leaves your iPhone or iPad.

Use the custom keyboard to write a message, choose a password, and insert an encrypted payload into Messages or another text field. Or open the Messages extension to stage a CryptKB bubble inside a Messages draft. The other person can open the same payload in CryptKB and decrypt it locally with the matching password.

Why people use CryptKB:

- Local encrypt and decrypt on device
- Custom keyboard for ordinary text fields
- Messages extension for composing and opening CryptKB bubbles
- AES-256-GCM encryption with PBKDF2-HMAC-SHA256 key derivation
- ASCII-safe payload format for copy, paste, and sharing
- Optional saved conversation passwords protected by Face ID or device passcode
- No account creation, no backend relay, no analytics SDKs, and no ad tracking in the app
- Built-in playground, settings, privacy notes, and diagnostics

How it works:

1. Switch to CryptKB Keyboard.
2. Type your message.
3. Enter a password.
4. Tap Encrypt & Insert.
5. Review the encrypted text and tap Send yourself.

To decrypt, paste or open a CryptKB payload, enter the matching password, and read the plaintext locally. CryptKB intentionally reveals decrypted text in a local panel instead of writing it back into the conversation automatically.

Important platform notes:

- Apple does not allow third-party keyboards to tap the host app's Send button, so sending is always manual.
- Password recovery is not possible by design.
- CryptKB protects message content inside its encrypted payload, not message metadata like recipients, timestamps, screenshots, or notification previews.