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AssetsBridge

A bridge from substrate assets(wasm) into ERC20 tokens(evm).

Overview

Substrate & EVM address on PSC

In AssetsBridge

  • substrate assets -> erc20 tokens: deposit
  • substrate assets <- erc20 tokens: withdraw
  • native currency(wasm) <-> eth(evm): teleport

Dispatchable Functions

  • for user:
    • claim_account: bond substrate account and evm address, will reserve some currency.
    • dissolve: unbond substrate account and evm address, will unreserve some currency.
    • deposit: move substrate assets into erc20 tokens.
    • withdraw: move back substrate assets from erc20 tokens.
    • teleport: transfer native currency between substrate account and evm address.
  • for admin:
    • register: bond substrate assets and erc20 contract address.
    • pause: pause deposit, withdraw and teleport(BackForeign) when in emergency.
    • unpause: unpause the paused state.
  • for sudo:
    • set_admin: set new the admin of AssetsBridge.
    • force_unregister: force unbond substrate assets and erc20 contract address.

In the production environment, the admin of assets-bridge must audits whether the erc20 contract implements IAssetsBridge interface and whether it has the AssetsBridgeAdmin modifier.

Work Flow

  • (1) bond Assets(wasm) and Tokens(evm): admin call register.
  • (2) bond Account(wasm) and Address(evm): user call claim_account.
  • (3) move assets(wasm and evm):
    • deposit: burn from wasm and mint into evm.
    • withdraw: burn from evm and mint into wasm.
    • teleport: transfer in wasm.
  • (4) maintenance：
    • for sudo: set_admin, force_unregister.
    • for admin: pause, unpause.
    • for user: dissolve.

Eth Signed Data Format

"evm:" + substrate_pubkey_hex_without_0x

example:

substrate account: 5USGSZK3raH3LD4uxvNTa23HN5VULnYrkXonRktyizTJUYg9
it's pubkey(hex): 0xd43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d
the sign data: "evm:d43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d"

companion with relay

  • Foreign assets(on other chain) -> PSC assets flow:

    • (1) user need transfer to the account which under the control of assets-bridge admin on foreign chain
    • (2) mint to user by assets-bridge admin on PSC

  • PSC assets -> Foreign assets(on other chain) flow:

    • (1) user need teleport with BackForeign(asset_id) on PSC.
    • (2) the account which under the control of assets-bridge admin on foreign chain transfer to user

  • maintenance by admin: back_foreign add or remove asset_id which can back foreign chain.

Note

For safety, AssetsBridge now only allows dependent AssetsBridge assets(wasm) and AssetsBridge tokens(evm).