---
id: TIP-1047
title: Revert code creation and set code at addresses with TIP-20 prefix
description: Reject contract creation and EIP-7702 delegations that produce addresses in the TIP-20 reserved prefix range
authors: Howy (@howydev)
status: Draft
related: TIP-20
protocolVersion: T5
---

# TIP-1047: Revert code creation and set code at addresses with TIP-20 prefix

## Abstract

Reject any CREATE, CREATE2, or EIP-7702 authorization that would produce or delegate to an address starting with the TIP-20 token prefix (`0x20C000000000000000000000`). Without this guard, anyone can place arbitrary bytecode at an address that the rest of the system treats as a TIP-20 token.

## Motivation

Multiple system components use `is_tip20_prefix` to decide whether an address is a TIP-20 token: precompile routing, fee-token validation, stablecoin DEX, and transaction classification. Code or a delegation at a prefix-matching address would pass these checks despite not being a real token.

CREATE and CREATE2 addresses are downstream of keccak; EIP-7702 authority addresses require secp256k1 point multiplication followed by keccak. Matching a 12-byte prefix requires ~2^96 work in all cases. This guard provides defense-in-depth by making such collisions fail-closed.

---

# Specification

## CREATE and CREATE2

Before setting up a create frame, compute the would-be contract address:

- **CREATE**: `keccak256(rlp(caller, nonce))[12..]`
- **CREATE2**: `keccak256(0xff ++ caller ++ salt ++ keccak256(init_code))[12..]`

If `is_tip20_prefix(address)` is true, revert the opcode. The caller's nonce is not bumped, no value is transferred, and no init-code is executed. Base opcode gas is consumed; init-code gas is not.

## EIP-7702 Authorizations

When processing EIP-7702 authorization lists, if `is_tip20_prefix(authority)` is true for a recovered authority address, skip the entry. The delegation is not applied.

---

# Invariants

1. **No new code at TIP-20 addresses**: No CREATE/CREATE2 produces a contract where `is_tip20_prefix` returns true. Applies to all depths (top-level and nested creates).

2. **No delegations to TIP-20 addresses**: No EIP-7702 authorization sets a delegation for an address where `is_tip20_prefix` returns true.

3. **Nonce preservation**: A rejected CREATE/CREATE2 does not bump the caller's nonce.

### Test coverage

- CREATE2 with a salt producing a TIP-20-prefixed address reverts without executing init-code.
- CREATE where the computed address has a TIP-20 prefix reverts with nonce unchanged.
- EIP-7702 authorization with a TIP-20-prefixed authority is skipped.
- Normal CREATE/CREATE2 producing non-TIP-20 addresses is unaffected.