Walk-Through Creation of a Personal Two-Factor Authentication Wallet / Contract

Question

I would like to create a multi-signature wallet to store large amounts of Ether with at least one signature from my Android phone (the other from my PC and/or another phone). What would be the cheapest and most user friendly way to accomplish this?

Are there any mobile wallets currently available that would allow me to sign a transaction for free or would I have to send the contract a Wei and have it validate the sender address? (Note: Jaxx I think forces HD Wallet behaviour, so it might cycle new addresses and that might not be very user friendly).

Answer 1

Since light protocole is not released, you won't have any direct mean to call a contract from a mobile phone app.

You can still find (I can't find one, Syng.io is over and I don't know what Syng.im will be) or create an app that connects to a node using RPC api, but you'll have to trust a node.

You could also create a contract that you can trigger only by sending a transaction with zero wei using Jaxx mobile wallet (but I'm not sure jaxx will let you send zero wei). This contract fallback checks the sender is you and calls your multi-sig contract validation function. You have to be sure to provide enough gas when calling the first.

You could also implement this directly in your multisig wallet fallback but then you have a add a way to know that you are not just sending eth to this wallet. you could check that the defined sender exactly sent 1 wei to triggers the validation. Then you could continue tu send ether to this contract if it's more than 1 wei.

Or you can wait for light clients...