IIP-60: Enable Ethereum Pectra Upgrade

Governance Proposals IIP Discussion
1

Abstract

This proposal introduces support for the Ethereum Pectra upgrade on the IoTeX network. The Pectra upgrade includes several EIPs that enhance the EVM capabilities, improve user experience, and strengthen cryptographic operations. Specifically, this IIP implements EIP-7702 (Set EOA Account Code), EIP-7623 (Increase Calldata Cost), EIP-2935 (Serve Historical Block Hashes from State), and EIP-2537 (Precompile for BLS12-381 Curve Operations).

Motivation

Maintaining EVM compatibility is crucial for the IoTeX ecosystem. By adopting the Ethereum Pectra upgrade, IoTeX ensures that developers can seamlessly deploy and interact with smart contracts using the latest Ethereum tooling and standards. The key benefits of this upgrade include:

  1. Enhanced Account Abstraction (EIP-7702): Allows EOAs to temporarily delegate to smart contract code, enabling batching, gas sponsorship, and privilege de-escalation without requiring users to migrate to smart contract wallets.

  2. Reduced Maximum Block Size (EIP-7623): Increases calldata costs for data-heavy transactions, reducing the maximum possible block size and improving network stability.

  3. Extended Block Hash History (EIP-2935): Stores historical block hashes in state, providing extended block hash history access (8191 blocks vs. 256 blocks) for applications and rollups. This change ensures compatibility with Ethereum’s Pectra upgrade.

  4. Enhanced Cryptographic Capabilities (EIP-2537): Adds BLS12-381 curve operations as precompiles, providing 120+ bits of security for pairing-based cryptographic operations such as BLS signature verification.

Specification

Implement EIP-7702: Set EOA Account Code

Overview

EIP-7702 introduces a new transaction type (0x04) that allows EOAs to set code in their account by attaching authorization tuples to the transaction.

Parameters

Parameter Value
SET_CODE_TX_TYPE 0x04
MAGIC 0x05
PER_AUTH_BASE_COST (TxAuthTupleGas) 12500
PER_EMPTY_ACCOUNT_COST (CallNewAccountGas) 25000

Transaction Format

rlp([chain_id, nonce, max_priority_fee_per_gas, max_fee_per_gas, gas_limit,
destination, value, data, access_list, authorization_list, signature_y_parity,
signature_r, signature_s])

authorization_list = [[chain_id, address, nonce, y_parity, r, s], ...]

Implementation Details

  1. Authorization Processing: For each authorization tuple [chain_id, address, nonce, y_parity, r, s]:

    • Verify the chain ID is 0 or the current chain ID
    • Recover the authority address using ecrecover(keccak(MAGIC || rlp([chain_id, address, nonce])), y_parity, r, s)
    • Verify the authority’s code is empty or already delegated
    • Set the authority’s code to 0xef0100 || address (delegation indicator)
    • Increment the authority’s nonce

  2. Delegation Indicator: The 0xef0100 || address prefix uses the banned opcode 0xef to indicate delegated code. All code executing operations (CALL, CALLCODE, DELEGATECALL, STATICCALL) must follow the delegation pointer.

  3. Gas Costs:

    • Intrinsic cost includes PER_EMPTY_ACCOUNT_COST * authorization_list_length initially
    • If the authority account already exists, refund PER_EMPTY_ACCOUNT_COST - PER_AUTH_BASE_COST (25000 - 12500 = 12500)

  4. Supported Action Types: SetCodeTx only supports execution and transfer action types. Native staking and rewarding actions are not supported.

Implement EIP-7623: Increase Calldata Cost

Overview

EIP-7623 increases calldata costs for data-heavy transactions to reduce maximum block size while maintaining low costs for regular transactions.

Parameters

Parameter Value Description
TX_BASE_GAS 10000 Base intrinsic gas for execution transactions
TX_TOKEN_PER_NONZERO_BYTE 1 Token per non-zero byte
TX_COST_FLOOR_PER_TOKEN 250 Cost floor per token

Implementation Details

  1. Token Calculation:
tokens = nonzero_bytes * TX_TOKEN_PER_NONZERO_BYTE + zero_bytes
  1. Floor Data Gas Calculation:
floorDataGas = TX_BASE_GAS + tokens * TX_COST_FLOOR_PER_TOKEN
  1. Gas Usage: After EVM execution completes, the actual gas used is:
gasUsed = max(normalGasUsed, floorDataGas)

  1. Transaction Validity: Transactions must have gas limit >= floorDataGas

  2. Impact: Regular transactions (IOTX transfers, DeFi, etc.) remain unaffected as they have significant EVM execution. Data-heavy transactions (primarily using calldata for DA) will see increased costs, with floor gas around 250 gas per byte.

Implement EIP-2935: Save Historical Block Hashes in State

Overview

EIP-2935 stores the last 8191 block hashes in a system contract’s storage, enabling stateless execution and extended history access.

Parameters

Parameter Value
BLOCKHASH_SERVE_WINDOW 256
HISTORY_SERVE_WINDOW 8191
SYSTEM_ADDRESS 0xfffffffffffffffffffffffffffffffffffffffe
HISTORY_STORAGE_ADDRESS 0x0000F90827F1C53a10cb7A02335B175320002935

Implementation Details

  1. Block Processing: At the start of each block (before transactions), invoke a system call to HISTORY_STORAGE_ADDRESS with:

    • Caller: SYSTEM_ADDRESS
    • Input: 32-byte block.parent.hash
    • Gas limit: 30,000,000
    • Value: 0

  2. Contract Operations:

    • set: Stores block.parent.hash at slot (block.number - 1) % HISTORY_SERVE_WINDOW
    • get: Returns the block hash for a given block number within the serve window

  3. Contract Deployment: Deploy the history contract at the fork activation block using the predefined deployment transaction.

  4. BLOCKHASH Opcode: Semantics remain unchanged; the contract provides extended history access via direct calls.

Implement EIP-2537: Precompile for BLS12-381 Curve Operations

Overview

EIP-2537 adds seven precompiles for BLS12-381 curve operations, enabling efficient BLS signature verification with 120+ bits of security.

Precompile Addresses and Gas Costs

Precompile Address Gas Cost
BLS12_G1ADD 0x0b 375
BLS12_G1MSM 0x0c Variable (see MSM formula)
BLS12_G2ADD 0x0d 600
BLS12_G2MSM 0x0e Variable (see MSM formula)
BLS12_PAIRING_CHECK 0x0f 32600*k + 37700
BLS12_MAP_FP_TO_G1 0x10 5500
BLS12_MAP_FP2_TO_G2 0x11 23800

Implementation Details

The implementation follows the Ethereum EIP-2537 specification exactly. For detailed encoding formats, gas formulas, and subgroup check requirements, refer to EIP-2537.

Rationale

EIP Selection

The selected EIPs represent the core functionality of the Ethereum Pectra upgrade that is most relevant to IoTeX:

  • EIP-7702 provides significant UX improvements for EOA users without requiring migration to smart contract wallets
  • EIP-7623 helps control block size, which is important for network stability
  • EIP-2935 provides extended block hash history access for applications and ensures Ethereum compatibility
  • EIP-2537 enables efficient BLS signature verification, important for bridges and cross-chain applications

IoTeX-Specific Adaptations

  • EIP-7623 Parameters: IoTeX’s base calldata gas cost differs from Ethereum (100 gas/byte vs 16 gas/byte). EIP-7623 aims to increase the floor cost to approximately 2.5x the original calldata cost. To maintain the same multiplier, IoTeX uses TX_COST_FLOOR_PER_TOKEN = 250 (100 × 2.5) instead of Ethereum’s TOTAL_COST_FLOOR_PER_TOKEN = 40 (16 × 2.5). The relative increase ratio is consistent; only the absolute values differ due to IoTeX’s different base gas parameters.

Compatibility Considerations

The implementation follows Ethereum specifications exactly to ensure maximum compatibility with existing tooling and contracts deployed on Ethereum.

Backwards Compatibility

This IIP is NOT backwards compatible and requires a hard fork. The following changes break existing invariants:

  1. EIP-7702:

    • Account balance can decrease from calls to delegated EOAs
    • EOA nonce may increase during transaction execution (via CREATE operations)
    • tx.origin == msg.sender is no longer guaranteed to be true only in the topmost frame

  2. EIP-7623:

    • Data-heavy transactions will require more gas
    • Wallet and RPC implementations must update gas estimation logic

  3. EIP-2935:

    • New system contract deployed at HISTORY_STORAGE_ADDRESS
    • Block processing logic modified to include system calls

  4. EIP-2537:

    • New precompile addresses (0x0b - 0x11) are now reserved

Security Considerations

EIP-7702

  • Delegation indicators persist after transaction failure; users must understand the implications of signing authorizations
  • Front-running initialization is possible if delegation and initialization are performed in separate transactions; implementations should combine delegation and initialization calls in a single atomic transaction
  • Storage collision risks when changing delegations; contracts should use ERC-7201 namespaced storage

Test Cases

Test cases will be adapted from the Ethereum execution-spec-tests repository:

Copyright

Copyright and related rights waived via CC0.