Add ERC: Temporary Approval Extension for ERC-20

ERCS/eip-draft-tae-erc20.md

@@ -0,0 +1,55 @@
+---
+title: Transient Approval Extension for ERC-20
+description: An interface for ERC-20 approvals via EIP-1153 transient storage
+author: Xenia Shape (@byshape), Mikhail Melnik (@ZumZoom)
+discussions-to: # TODO: update
+status: Draft
+type: Standards Track
+category: ERC
+created: 2024-04-02
+requires: 20, 1153
+---
+
+## Abstract
+
+This specification defines the minimum interface required to transiently approve `ERC-20` tokens for spending within a single transaction.
+
+## Motivation
+
+`EIP-1153` allows to use a cheaper way to transiently store allowances.
+
+## Specification
+
+The key words "MUST", "SHOULD", "MAY" in this document are to be interpreted as described in RFC 2119 and RFC 8174.
+
+Compliant contracts MUST implement 1 new function in addition to `ERC-20`:
+```solidity
+function transientApprove(address spender, uint256 value) public returns (bool success)
+```
+Call to `transientApprove(spender, value)` allows `spender` to withdraw within the same transaction from `msg.sender` multiple times, up to the `value` amount.
+
+Compliant contracts MUST use the transient storage `EIP-1153` to keep the temporary allowance. For each `owner` and `spender`, the slot MUST be uniquely selected to avoid slot collision. Each slot index SHOULD be derived from the base slot index for transient allowances, `owner` and `spender` addresses. Slot MAY be derived as `keccak256(spender . keccak256(owner . p))` where `.` is concatenation and `p` is `keccak256` from the string uniquely defining transient allowances in the namespace of the implementing contract.
+
+Compliant contracts MUST add a transient allowance check to the `transferFrom` function. The permanent allowance can only be spent after the temporary allowance has been exhausted.
+
+Compliant contracts MUST add a transient allowance to the permanent one when returning the allowed amount to spend in the `allowance` function.
+
+## Rationale
+
+The main goal of this standard is to make it cheaper to approve `ERC-20` tokens for a single transaction with minimal interface extension to allow easier integration of a compliant contract into existing infrastructure. This affects the backward compatibility of the `allowance` and `transferFrom` functions.
+
+## Backwards Compatibility
+
+All functionality of the `ERC-20` standard is backward compatible except for the `allowance` and `transferFrom` functions.
+
+## Reference Implementation
+
+The reference implementation can be found [here](https://github.com/byshape/transient-token/blob/main/contracts/TransientToken.sol).
+
+## Security Considerations
+
+The method of deriving slot identifiers to store temporary allowances must avoid collision with other transient storage slots.
+
+## Copyright
+
+Copyright and related rights waived via [CC0](../LICENSE.md).