Add AOPP support

AOPP (Address Ownership Proof Protocol) is a new, simple protocol that specifies the transmission of signed messages via a URI scheme.

Providing proof of ownership over an address is required to withdraw cryptocurrencies in some countries (Switzerland, the Netherlands, Singapore). It’s a hassle to do that manually for the user and the exchange. AOPP heavily improves that. See for more information about it.

Besides improving the UX for the user, there are two more benefits:

  1. There is no need to copy & paste an Ethereum address for the wallet to the exchange to withdraw. This prevents malware from replacing it in the clipboard
  2. The wallet is aware that the user is withdrawing from an exchange (even which exchange) and with that can suggest other options, which might be better for his privacy, provide better fees or better technology (e.g. segwit support, etc.).

AOPP does not affect and is not even visible to users of exchanges who don’t have AOPP (don’t require ownership proof).