Eos bank

Any user who wishes to use or send EOS on the EOS blockchain needs an account. Due to the inherent cost and limits on accounts that the network can have, I propose a smart contract that will work as the middle man between the EOS blockchain and users without accounts

Key pieces:

Bank contract & account
Relay account/s
Key pair (EOS/RSA/ECC/...)

Definitions

Bank contract

Smart contract that will:

Hold a table of users
Enable transactions with the users funds
Handle automatic delegation of resources and ram purchases

Relay account

The relay accounts will be public accounts without funds, used to communicated with the blockchain.

Key pair

The user will need to create a key pair using a supported key, this will be used to sing the transactions that the user wants to perform and will be relayed to the bank contract by the relays

Scenarios

A user wants to withdraw EOS from the exchange

The user creates a key pair
Withdraw the funds to the bank contract, adding the public key in the memo

The user wants to transfer funds on the bank

The user creates an action that includes the details of the transaction (from, to, quantity, random number, signature of previous parameters)
The user send this action using any relay account
The bank contract will validate the signature, add the random number as used (to prevent replay attacks) and execute the action

Allocation of resources

This contract will need bandwidth for the actions and ram for the account storage.

The bandwidth could be offered by some third party to support the contract or on last resort the bank contract could stake the received funds.
For RAM, as it not renewable, will be payed out by the user. When the user does a deposit and creates a new account the contract will try to buy ram to hold it’s account (from 200-600 bytes). When the user withdraws all the funds and the account is removed, the ram will be sold and the value returned too.