What is Certified Send?

Certified Send is a City of Hats feature that provides cryptographic proof that a message was delivered, opened, and read. It generates tamper-proof receipts and opens content in a protected viewer that prevents screenshots and forwarding.

How does the Proof of Receipt work?

When the recipient opens a Certified Send message, the app generates a cryptographic receipt with a timestamp, recipient Hat code, and content hash. This receipt is signed and cannot be forged or altered. The sender receives it as proof the message was read.

What is the Protected Viewer?

The Protected Viewer is a secure reading environment that prevents screenshots, screen recording, copy-paste, and forwarding. Content is displayed in a controlled viewer that ensures the message stays between sender and recipient.

Can the receipt be faked or tampered with?

No. Proof of Receipt is cryptographically signed using the recipient's device keys. The signature includes a timestamp and content hash, making any tampering immediately detectable. It is mathematically verifiable proof.

Certified Send — Cryptographic Proof of Delivery & Reading

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