The Hedera Account Service (HAS) System Contract is accessible at address 0x16a on the Hedera network. This contract interface introduces a new account proxy contract to interact with other contracts for functionality such as HBAR allowances. It enables querying and granting HBAR approval to a spender account from within smart contracts, allowing developers to grant, retrieve, and manage HBAR allowances directly in their code. Additionally, HAS can verify whether a given address (Hedera account or EVM address) is authorized based on a provided message hash and signature through the isAuthorizedRaw method.
The table below outlines the available Hedera Account Service System Contract functions:
| Function Name | Function Selector Hash | Consensus Node Release Version | HIP | Method Interface |
|---|---|---|---|---|
hbarAllowance |
0xbbee989e |
0.52 | HIP 906 | hbarAllowance(address spender) |
hbarApprove |
0x86aff07c |
0.52 | HIP 906 | hbarApprove(address spender, int256 amount) |
isAuthorizedRaw |
0xb2a31da4 |
0.52 | HIP 632 | isAuthorizedRaw(address, bytes /*messageHash*/, bytes /*signatureBlob*/) |
isAuthorized |
0xb2526367 |
0.56 | HIP 632 | isAuthorizedRaw(address, bytes /*messageHash*/, bytes /*signatureBlob*/) |
The Hedera network also make facade contract calls available to EOAs for improved experience. Facade function allow for EOAs to make calls without requiring a deployed contract The table below outlines the available Hedera Account Service (HAS) System Contract facade functions:
| Function Name | Function Selector Hash | Consensus Node Release Version | HIP | Method Interface | Comments |
|---|---|---|---|---|---|
setUnlimitedAutomaticAssociations |
0xf5677e99 |
0.56 | HIP 904 | setUnlimitedAutomaticAssociations(bool enableAutoAssociations) external returns (int64 responseCode) |