Cryptogram Cipher
Robby Riedel
Some messages belong between the two of you. A settlement proposal. A tip for an investigation. A conversation about health. Cryptogramm encrypts sensitive texts on your iPhone. You share the block of characters by chat or e-mail. FOR LAWYERS At an appointment in your office, you and your client set up your shared key. From then on, your client sends their view on a settlement as an encrypted block of characters by e-mail. You open it in Cryptogramm. FOR JOURNALISTS A source encrypts their tip before sending it. A short meeting point they leave on an agreed NFC sticker – with an expiry time, or readable only once on an NTAG 424 DNA. You can share locations in encrypted form too. FOR EVERYDAY LIFE You discuss your parents' care with your sister, or send your partner the access code for the holiday flat. Encrypt the text and share it over the channel you trust. Short notes you leave on an NFC sticker for later pickup. THE LOCKED NFC DEAD DROP Besides ordinary NFC stickers, Cryptogramm supports the NTAG 424 DNA. It releases its content only after authentication with the matching key. A stranger's phone does not even see the encrypted text there. The app sets up a new NTAG 424 DNA the first time you write to it, in the same tap. With a different key it stops without changing the tag. Resetting with the matching key wipes the tag completely and turns it back into an ordinary sticker. READABLE ONCE ONLY On the NTAG 424 DNA the chip itself enforces the single read: it counts the pickup and prevents the message from being opened again afterwards – even by you. Simply tapping it with a stranger's phone does not use up the single read. About 250 characters fit into an ordinary message, about 108 into one that is readable once only. The label and the sender take up part of that. The input field shows how much still fits. MESSAGES WITH AN EXPIRY TIME One hour, one day, one week, 30 days or an exact moment: you decide how long a message stays readable in the dead drop. The expiry time is encrypted along with it. Cryptogramm no longer shows expired messages and overwrites them when they are read. Can be combined with reading once only. SHARE AND BACK UP KEYS Hand over your shared key by QR code, AirDrop or link. The link opens Cryptogramm on the other iPhone and asks for the one-time code. Send that code separately, by a different route. The key passport backs up your key on a folded A5 card – also for a lost phone or an emergency wipe. Keep it in a safe: it is as valuable as the key itself. EMERGENCY WIPE AS A SHORTCUT Delete your local keys without confirmation and without opening the app: with the Action button, a double tap on the back of the phone or an automation. PRIVACY AND EU CHAT CONTROL The EU interim regulation allows certain providers, under conditions, to carry out voluntary checks to combat child sexual abuse. It applies until 3 April 2028; end-to-end encrypted communication is exempt. The permanent regulation is still being negotiated. As of October 2026. Optical paper codes can be copied by hand and read with the camera. Encrypting and decrypting also work in airplane mode. NO ACCOUNT. NO SUBSCRIPTION. Access with Face ID or the device passcode. Locally protected keys, fixed deletion deadlines, no provider servers, no ads, no tracking. Nine languages, now including Russian. GOOD TO KNOW Both of you need the app and the same key. Who communicates with whom and when remains visible to the messenger. A key obtained later can open older ordinary messages. Deliberately reading the tag with an NFC app can make a once-only message unreadable without decrypting it. Reading once only does not prevent copies at the moment of pickup. Without the key it was set up with, an NTAG 424 DNA stays locked for good. Buy once. Give what's private the protection it deserves.
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