How It Works

What is FHE?

Fully Homomorphic Encryption (FHE) is a breakthrough in cryptography that allows computations on encrypted data without ever decrypting it.

blockmsg uses Zama’s fhEVM to bring FHE to the blockchain.

The Encryption Process

Message Chunking

Your message is split into 32-bit segments in your browser

FHE Encryption

Each chunk is encrypted using TFHE.asEuint32 - plaintext never leaves your device

On-Chain Storage

Encrypted handles are stored on the Zama fhEVM blockchain

Recipient Decryption

Recipient signs with wallet → re-encryption → local decryption

Smart Contract Architecture

SecretCircles Contract

The main contract handles:

Storing FHE-encrypted messages
Managing DM channels between wallets
Self-destruct timer logic
Access control for decryption

Data Structure

struct DirectMessage {
    address sender;
    uint256 timestamp;
    euint32[] encryptedContent;  // FHE encrypted
    uint256 expiresAt;
}

Self-Destructing Messages

Set a timer on your messages. Once expired, the smart contract returns an empty array - the message becomes permanently unreadable.

Timer	Use Case
5 minutes	Quick sensitive info
1 hour	Short-term coordination
12 hours	Day-limited conversations
24 hours	Daily check-ins
7 days	Weekly updates

Self-destructed messages cannot be recovered by anyone - not even us.

Technical Stack

fhEVM by Zama

Fully Homomorphic Encryption virtual machine

Solidity

Smart contracts for encrypted message management

Next.js

Frontend application framework

fhevmjs

Client-side FHE encryption library

Getting Started

Features

Developers

What is FHE?

The Encryption Process

Smart Contract Architecture

Self-Destructing Messages

Technical Stack

fhEVM by Zama

Solidity

Next.js

fhevmjs

​What is FHE?

​The Encryption Process

​Smart Contract Architecture

​Self-Destructing Messages

​Technical Stack

fhEVM by Zama

Solidity

Next.js

fhevmjs

What is FHE?

The Encryption Process

Smart Contract Architecture

Self-Destructing Messages

Technical Stack