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fix: lower zone chain ID base to stay within EIP-2294 safe range (#361)
* fix: lower zone chain ID base to stay within EIP-2294 safe range Co-authored-by: Daniel Robinson <[email protected]> Amp-Thread-ID: https://ampcode.com/threads/T-019d54ae-a5ca-74b9-bd73-f71e8add4cad * fix: wrap zone chain IDs to stay within safe range Use modular arithmetic so zone chain IDs never exceed 2^31 - 1. Sequencers are responsible for ensuring their derived chain ID does not collide with any active chain. Co-authored-by: Daniel Robinson <[email protected]> Amp-Thread-ID: https://ampcode.com/threads/T-019d54ae-a5ca-74b9-bd73-f71e8add4cad --------- Co-authored-by: Daniel Robinson <[email protected]>
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‎crates/primitives/src/constants.rs‎

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@@ -83,14 +83,67 @@ pub const ZONE_OUTBOX_LAST_BATCH_INDEX_SLOT: U256 = {
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U256::from_le_bytes(le)
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};
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/// Base offset for deriving zone chain IDs: `4217000000 + zone_id`.
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/// Base offset for deriving **mainnet** zone chain IDs.
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///
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/// Each zone gets a unique EIP-155 chain ID derived from its on-chain zone ID
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/// assigned by the `ZoneFactory` contract. The prefix `4217` comes from the
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/// Tempo L1 chain ID.
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pub const ZONE_CHAIN_ID_BASE: u64 = 4_217_000_000;
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/// assigned by the `ZoneFactory` contract:
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///
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/// ```text
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/// chain_id = ZONE_CHAIN_ID_BASE + (zone_id % ZONE_CHAIN_ID_RANGE)
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/// ```
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///
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/// # Range safety
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///
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/// EIP-2294 and ENSIP-11 reserve bit 31 (`0x8000_0000`) for coin-type flags,
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/// making chain IDs ≥ 2^31 (2,147,483,647) unsafe in parts of the ecosystem
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/// (ENS multi-chain address resolution, some JavaScript tooling that uses
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/// 32-bit integers, etc.).
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///
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/// The ranges are chosen so that both mainnet and testnet zones stay well below
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/// that limit while remaining non-overlapping:
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///
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/// | Network | Base | Range size | Chain ID span |
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/// |----------|-----------------|-------------------|---------------------------------------|
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/// | Mainnet | `421_700_000` | `1_002_610_000` | `421_700_000 .. 1_424_310_000` |
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/// | Testnet | `1_424_310_000` | `723_173_648` | `1_424_310_000 .. 2_147_483_648` |
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///
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/// Zone IDs wrap around via modular arithmetic so that chain IDs never leave
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/// their designated range, even with arbitrarily large zone IDs. Because
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/// wrapping can reuse a chain ID that was previously assigned to a different
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/// zone, it is the responsibility of the sequencer to ensure — after deploying
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/// a zone — that the derived chain ID does not correspond to any active chain,
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/// including any zone that has previously used that chain ID.
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pub const ZONE_CHAIN_ID_BASE: u64 = 421_700_000;
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/// Number of distinct mainnet zone chain IDs before wrapping.
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///
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/// Equal to `ZONE_CHAIN_ID_BASE_TESTNET - ZONE_CHAIN_ID_BASE`, keeping the
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/// mainnet range strictly below the testnet range.
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pub const ZONE_CHAIN_ID_RANGE: u64 = 1_002_610_000;
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/// Derives the EIP-155 chain ID for a zone from its on-chain zone ID.
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/// Base offset for deriving **testnet** (Moderato) zone chain IDs.
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///
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/// See [`ZONE_CHAIN_ID_BASE`] for range-safety rationale.
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pub const ZONE_CHAIN_ID_BASE_TESTNET: u64 = 1_424_310_000;
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/// Number of distinct testnet zone chain IDs before wrapping.
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///
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/// Equal to `2^31 - ZONE_CHAIN_ID_BASE_TESTNET`, keeping the testnet range
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/// strictly below the EIP-2294 safe ceiling.
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pub const ZONE_CHAIN_ID_RANGE_TESTNET: u64 = 723_173_648;
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/// Derives the EIP-155 chain ID for a **mainnet** zone from its on-chain zone ID.
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///
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/// Wraps via modulo so the result always falls in
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/// `[ZONE_CHAIN_ID_BASE, ZONE_CHAIN_ID_BASE + ZONE_CHAIN_ID_RANGE)`.
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pub const fn zone_chain_id(zone_id: u32) -> u64 {
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ZONE_CHAIN_ID_BASE + zone_id as u64
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ZONE_CHAIN_ID_BASE + (zone_id as u64 % ZONE_CHAIN_ID_RANGE)
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}
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/// Derives the EIP-155 chain ID for a **testnet** zone from its on-chain zone ID.
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///
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/// Wraps via modulo so the result always falls in
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/// `[ZONE_CHAIN_ID_BASE_TESTNET, ZONE_CHAIN_ID_BASE_TESTNET + ZONE_CHAIN_ID_RANGE_TESTNET)`.
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pub const fn zone_chain_id_testnet(zone_id: u32) -> u64 {
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ZONE_CHAIN_ID_BASE_TESTNET + (zone_id as u64 % ZONE_CHAIN_ID_RANGE_TESTNET)
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}

‎docs/ZONES.md‎

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@@ -492,7 +492,7 @@ The xtasks use this Moderato `ZoneFactory` as their built-in default: `create-zo
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| `--l1.rpc-url` | (required) | L1 WebSocket RPC URL |
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| `--l1.portal-address` | (from zone.json) | ZonePortal contract on L1 |
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| `--l1.genesis-block-number` | (from zone.json) | L1 block when the zone was created |
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| `--zone.id` | 0 | Zone ID from ZoneFactory (for private RPC auth). The zone's chain ID is derived as `4217000000 + zone_id`. |
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| `--zone.id` | 0 | Zone ID from ZoneFactory (for private RPC auth). The zone's chain ID is derived as `421700000 + (zone_id % 1002610000)` (mainnet) or `1424310000 + (zone_id % 723173648)` (testnet). |
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| `--sequencer-key` | (optional) | Sequencer private key for block production |
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| `--block.interval-ms` | 250 | Block building interval |
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| `--zone.batch-interval-secs` | 60 | Max seconds to accumulate zone blocks before submitting a batch to L1 |

‎docs/specs/privacy/overview.md‎

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@@ -62,10 +62,18 @@ The factory deploys a `ZonePortal` that escrows enabled tokens on Tempo and a `Z
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Each zone has a unique EIP-155 chain ID derived deterministically from its on-chain zone ID:
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```
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chain_id = 4217000000 + zone_id
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# Mainnet zones (range: 421,700,000 – 1,424,309,999)
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chain_id = 421700000 + (zone_id % 1002610000)
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# Testnet / Moderato zones (range: 1,424,310,000 – 2,147,483,647)
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chain_id = 1424310000 + (zone_id % 723173648)
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```
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The prefix `4217` corresponds to the Tempo L1 chain ID. This ensures replay protection between zones — a transaction signed for one zone cannot be replayed on another. The chain ID is set in the zone's genesis configuration during creation and validated by the zone node at startup.
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Both ranges stay below `2^31 − 1` (2,147,483,647), which is the safe ceiling defined by EIP-2294 and ENSIP-11. Chain IDs above this limit can break ENS multi-chain address resolution and JavaScript tooling that uses 32-bit integers. Zone IDs wrap via modular arithmetic so that the derived chain ID always stays within the designated range.
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Because wrapping can reuse a chain ID that was previously assigned to a different zone, it is the responsibility of the sequencer to ensure — after deploying a zone — that the derived chain ID does not correspond to any active chain, including any zone that has previously used that chain ID.
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This ensures replay protection between zones — a transaction signed for one zone cannot be replayed on another. The chain ID is set in the zone's genesis configuration during creation and validated by the zone node at startup.
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### Token management
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‎zone-genesis/genesis.json‎

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{
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"config": {
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"chainId": 4217000001,
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"chainId": 421700001,
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"homesteadBlock": 0,
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"daoForkSupport": false,
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"eip150Block": 0,

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