Fix: Signature verify when create wallet (not using RELAY)

[patogallaiovlabs]

Tests (BIG Disclaimer!!!)

• This has only been tested manually, no formal test developed nor modified in this PR so far, this is a draft.

Context

When using the SmartWalletFactory contract without using the relay, directly from an EOA, the function "createUserSmartWallet" is called. This function checks if the signature belongs to the owner of the wallet and that the message signed is: hash(<owner> + <recoverer> + <index>).

Issue

Using Metamask/Nifty wallets at the moment of signing the message, a prefix is added so the final message would be:
"\x19Ethereum Signed Message:\n" + msg.length + hash(<owner> + <recoverer> + <index>).
This is due to eth_sign is deprecated by those wallets:

• https://github.com/poanetwork/nifty-wallet/blob/master/CHANGELOG.md#399-2017-8-18
• Replace eth_sign behavior with eth_personalSign behavior MetaMask/metamask-extension#2215

Solution

So, in order to be compatible with this behaviour is that in this PR the verification of the signature (only in the case of direct deploy, without use of the RELAY mechanism) has been changed to the following:

• Message to sign in the client side is: hash(<verifier_address> + <owner> + <recoverer> + <index>)
• Client should use presonal_sign function (which prepends "\x19Ethereum Signed Message:\n" + msg.length).
• The recovery process in the Contract is:
  • msg = "\x19Ethereum Signed Message:\n" + msg.length + hash(<verifier_address>+<owner> + <recoverer> + <index>)
  • hash(msg).recover(signature)

[raullaprida]

@mortelli You can add me as reviewer once it is ready-for-review!

[mortelli]

relevant PRs:

1. contracts
2. tests

[antomor]

These changes have been included in the relevant PRs.