CryptKB

Send whole cipher-text. Encrypt message text locally with a custom keyboard and Messages extension. No servers, no analytics, optional Face ID protected saved passwords.

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.