cell/examples/seif_server.js

// Seif Handshake Server Example
// Implements the Seif Protocol handshake as described in the documentation

var crypto = use('crypto');
var json = use('json');
var io = use('io');

// Server's key pair
var server_keys = crypto.keypair();
console.log("Server public key:", server_keys.public);
console.log("Server private key:", server_keys.private);

// Store connected clients
var clients = {};

$_.portal(e => {
  // Verify the handshake message format
  if (!e.seif || !e.handshake || !e.payload) {
    send(e, {error:"Invalid Seif handshake format"});
    return;
  }
  
  if (e.seif !== 1) {
    send(e, {error:"Unsupported Seif protocol version:", e.seif});
    return;
  }
  
  try {
    // Decrypt the handshake key with server's private key
    var handshake_key_encrypted = e.handshake;
    var handshake_key_hex = crypto.decrypt_pk(server_keys.private, handshake_key_encrypted);
    
    // Convert ArrayBuffer to hex string
    var handshake_key_bytes = new Uint8Array(handshake_key_hex);
    var handshake_key = '';
    for (var i = 0; i < handshake_key_bytes.length; i++) {
      var hex = handshake_key_bytes[i].toString(16);
      handshake_key += (hex.length === 1 ? '0' : '') + hex;
    }
    
    console.log("Decrypted handshake key:", handshake_key);
    
    // Decrypt the payload (client's public key) with handshake key
    var client_public_encrypted = e.payload;
    var client_public_buffer = crypto.decrypt(handshake_key, client_public_encrypted);
    
    // Convert decrypted buffer to string
    var client_public_bytes = new Uint8Array(client_public_buffer);
    var client_public = '';
    for (var i = 0; i < client_public_bytes.length; i++) {
      client_public += String.fromCharCode(client_public_bytes[i]);
    }
    
    console.log("Client's public key:", client_public);
    
    // Generate session key
    var session_key = crypto.keypair();
    console.log("Generated session key:", session_key.public);
    
    // Create response encrypted with handshake key
    var response = {
      session: crypto.encrypt_pk(client_public, session_key.public)
    };
    
    var response_encrypted = crypto.encrypt(handshake_key, json.encode(response));
    
    // Send encrypted response
    send(e, response_encrypted);
    
    console.log("Handshake complete with client:", client_public);
    
  } catch (err) {
    send(e, {error:err})
  }
}, 5678);

// Handle messages from connected clients
$_.receiver(e => {
  if (e.type === 'encrypted_message') {
    console.log("Received encrypted message");
    // In a real implementation, decrypt with session key and process
  }
});

console.log("Seif server listening on port 5678");