Copay, joining a wallet overview

gistfile1.txt

Joining a wallet
================

Creator (C) <-> Joining Peer (J)

(J)
  <- Hello (secret random, peerPubkey) encrypted with creatorPubkey

(C)
  (async._addConnectedPeer, emit 'connect', w.sendWalletId)
  ->  walletId (wallet options)

(J)
  (peer creates the wallet with the wallet Id and sends:  
  <- walletReady (walletId)

(C)
  (w._onData)
  -> PublicKeyRing, AddressBook, TxProposals.

Proposal:

1. Shared string: URL + Secret. URL is something like: https://copay.io/wallets/<id>

2. (c)
   POST URL /wallets

   • wallet options (encrypted with secret)
   • pkr (encrypted with secret)
     <- walletId.

3. (J)
   GET URL.
   <- wallet opts, pkr, status
   POST URL
   pkr

   GET URL/status
   [...]

Then everyone uses the mailboxes.
no more helo, walletId, walletReady, pubkeyring messages.

Storage

1. All devices, store WALLET_CRITICAL_DATA (WCD):

• Extended Private Key
• WalletID
• Pub Key Ring (could be incomplete) (i.e. copayers Extended Public Key, and copayer's aliases)
• if (!isComplete) Wallet Creation URL

Device mobility is possible when moving the WCD on a file or similar between devices. New devices can sync Wallet Extended Data (WED) from the Copa Server.

Communication (WED)

Communications thru Shared mailbox ONLY happen when the ring is complete.

• copayerId = pub key derivation of the ext pub key of certain path.
• walletEncKey = f(pkr)
• mailboxId = f(walletId, pkr)
• mailboxWriteSecret= f2(walletId, prk) (for the server to limit who can write the shared mbox)

All message have header: mailboxWriteSecret, which is checked by the server.

Shared mailbox

It is created by any of the copayers
/walletMailbox/<mailboxId>/list/<type>
/walletMailbox/<mailboxId>/state/<type>/copayerId
-> Signed with copayerId, encrypted with walletEncKey.

State (overwritten, one item per copayer)

• Indexes
• My name
• My Addressbook
  ...

List (limited list, FIFO).

• Tx proposals

TODO: TxProposals expiration / deletion policy