EVM Chains
Example for Ethereum.
The EVM Bifrost is different to others in that it uses a router to handle deposits into and out of THORChain vaults. The Router is just a means for capturing token deposits and emitting memos.
The Router holds all ERC20s, but forwards ETH to the TSS vault. This allows the TSS Vault to call into the Router and pay gas to move token allowances to vaults.
Instead of paying ERC20s to vault addresses, an allowance to spend is given on the Router. The depositing user gives this allowance to the Asgard vault, which itself moves the allowance to each Ygg vault. Thus each Ygg vault can call into the Router to transfer out inside their allowances. This is a very gas-efficient way of achieving vault funding.
Additionally because of this, the Router is a permissionless contract with no special privileges (there is no owner).
The Router is necessary because the ERC20 standard has no "push" functionality, and no ability to attach native memos. The Router uses the transferFrom "pull" and emits an event with a memo string.
The block scanner monitors the Router events, and can create a witness transaction based on this event.
Incomings are "conf-counted"
