ECIP 1130: Bastion EVM and Protocol Upgrades Source

AuthorDiego López León, Istora Mandiri
Discussions-Tohttps://github.com/orgs/ethereumclassic/discussions/575
StatusDraft
TypeMeta
Created2026-06-30

Simple Summary

Enable a subset of the Ethereum Foundation Cancun, Prague and Osaka execution-layer protocol upgrades on the Ethereum Classic network in a hard-fork code-named Bastion to enhance compatibility across these networks.

Abstract

Add support for a subset of protocol-impacting changes introduced in the Ethereum Foundation (ETH) network via the Cancun (Mar 2024), Prague (May 2025) and Osaka (Dec 2025, the execution-layer half of “Fusaka”) network upgrades. The proposed changes for Ethereum Classic’s Bastion upgrade include:

EIP Description Status
1153 Transient storage opcodes (TLOAD / TSTORE) Include
5656 MCOPY opcode Include
6780 SELFDESTRUCT only in same transaction Include
2537 Precompiles for BLS12-381 curve operations Include
7823 Set upper bounds for MODEXP inputs Include
7883 MODEXP gas cost increase Include
7939 CLZ opcode (count leading zeros) Include
7951 Precompile for secp256r1 (P256VERIFY) Include

This document proposes the following blocks at which to implement these changes in the Ethereum Classic networks:

  • TBD on Mordor testnet
  • TBD on Ethereum Classic mainnet

For more information on the opcodes, precompiles and their respective EIPs and implementations, please see the Specification section of this document.

EIP Summaries and expected action

Included

  • EIP-1153 “Transient storage opcodes”: Adds TLOAD (0x5C) and TSTORE (0x5D), a per-transaction key/value store discarded at end of the top-level call frame.
  • EIP-5656 “MCOPY opcode”: Adds MCOPY (0x5E), an efficient memory-to-memory copy instruction with memmove semantics.
  • EIP-6780 “SELFDESTRUCT only in same transaction”: Restricts SELFDESTRUCT (0xFF) to delete account, storage and code only when the contract was created in the same transaction; otherwise only the balance is transferred.
  • EIP-2537 “BLS12-381 precompiles”: Adds precompiles at 0x0B–0x12 exposing BLS12-381 G1/G2 add, MSM, pairing check and field-to-curve maps.
  • EIP-7823 “Upper bounds for MODEXP”: Caps each MODEXP input at 1024 bytes; out-of-bounds calls consume all supplied gas and return failure.
  • EIP-7883 “MODEXP gas cost increase”: Re-prices MODEXP with a minimum of 500 gas, a higher per-word multiplier for inputs > 32 bytes, and a doubled multiplication-complexity branch for inputs > 32 bytes. Paired with EIP-7823.
  • EIP-7939 “CLZ opcode”: Adds CLZ (0x1E), returning the count of leading zero bits of a 256-bit word (256 if the operand is zero); 3 gas.
  • EIP-7951 “secp256r1 precompile”: Adds P256VERIFY at 0x100, verifying an ECDSA signature over NIST P-256 at a fixed cost of 6900 gas; enables WebAuthn / passkey signature verification on-chain.

Omitted (not applicable to ETC)

The following EIPs from the source upgrades assume Proof-of-Stake, the Beacon Chain, blob data availability, or the EIP-1559 fee market — none of which ETC has adopted — and are therefore omitted from Bastion:

  • From Cancun: EIP-4788 (Beacon block root in the EVM), EIP-4844 (Shard Blob Transactions), EIP-7516 (BLOBBASEFEE).
  • From Prague: EIP-6110 (validator deposits on-chain), EIP-7002 (EL-triggerable exits), EIP-7251 (MAX_EFFECTIVE_BALANCE), EIP-7549 (committee index outside attestation), EIP-7685 (EL requests), EIP-7691 (blob throughput), EIP-7840 (blob schedule in EL config).
  • From Osaka: EIP-7594 (PeerDAS), EIP-7892 (blob parameter-only forks), EIP-7918 (blob base-fee floor).

Deferred (EL-applicable, but left for a follow-up ECIP)

  • EIP-2935 “Serve historical block hashes from state”: the upstream motivation is to bundle historical block hashes into witnesses for stateless / Verkle clients, with a secondary use case of extending the history window available to rollups. ETC has not committed to a stateless transition and has no L2 rollup ecosystem consuming this surface; defer until the ETC stateless roadmap is defined.
  • EIP-7623 “Increase calldata cost”: fee-market tuning anchored in EIP-1559 economics; ETC needs a native cost model under ECIP-1017 before adopting.
  • EIP-7702 “Set EOA account code”: the authorization-cost schedule and gas accounting reference EIP-1559 + BASEFEE, which ETC did not adopt in Mystique; the upstream spec is still evolving (chain-id binding, nonce semantics, revocation flows) and the replay/sponsorship surface observed on Ethereum mainnet post-Pectra should be reviewed before adoption. Out of scope for Bastion; candidate for a follow-up ECIP.
  • EIP-7825 “Transaction gas limit cap”: caps individual transactions at 2^24 (16,777,216) gas. The upstream motivation is anchored in Ethereum’s growing block gas limit and in the throughput increases shipped through the blob / PeerDAS path — contexts in which a single unbounded transaction can monopolize a block. Ethereum Classic’s block gas limit currently sits well below the proposed per-tx cap, and ETC has no blob path; the cap has no observable effect under present conditions. Defer until either ETC’s block gas limit is raised above the EIP-7825 cap or a comparable throughput-expanding change is on the roadmap.
  • EIP-7935 “Default gas limit to 60M”: advisory only; on ETC miners set the gas limit, so any default should be debated separately.

Motivation

To extend the Ethereum Virtual Machine’s (EVM) capabilities, various opcodes and precompiles shall be added to the Ethereum Classic networks, all of which have been in use on the Ethereum Foundation networks since the Cancun (March 2024), Prague (May 2025) and Osaka (December 2025) activations. This keeps Ethereum Classic at parity with the post-Cancun EVM consumed by Solidity, Vyper, Hardhat, Foundry, and audit tooling, and adds support for the BLS12-381 (ZK / threshold signatures) and secp256r1 (WebAuthn / passkeys) cryptographic primitives.

EIP-7823 and EIP-7883 are included as a pair: adopting EIP-7883 alone leaves the bounded-input branch under-priced relative to current benchmarks, and adopting EIP-7823 alone retains the legacy pricing for unbounded inputs.

Specification

Technical specifications for each EIP can be found at those documents respectively:

  • EIP-1153: Transient storage opcodes
  • EIP-5656: MCOPY — Memory copying instruction
  • EIP-6780: SELFDESTRUCT only in same transaction
  • EIP-2537: Precompile for BLS12-381 curve operations
  • EIP-7823: Set upper bounds for MODEXP
  • EIP-7883: MODEXP gas cost increase
  • EIP-7939: Count leading zeros (CLZ) opcode
  • EIP-7951: Precompile for secp256r1 curve support

Rationale

Interoperability: Maintaining interoperable behavior between Ethereum clients reduces friction for developers and end-users across the participating chains (e.g., ETH and ETC, Sepolia / Hoodi and Mordor).

Immutability: New opcodes (TLOAD, TSTORE, MCOPY, CLZ) occupy previously-invalid opcode slots, and new precompiles (BLS12-381 range, P256VERIFY) occupy previously-empty addresses; none of them can alter the behavior of existing contracts.

Continuation of the SELFDESTRUCT deprecation: EIP-6780 is the operational follow-up to EIP-6049, which Ethereum Classic adopted in Spiral (ECIP-1109). EIP-6049 formally deprecated SELFDESTRUCT and signalled to developers that future hard-forks would change its behavior; EIP-6780 is the first such change. The opcode is preserved, balance transfer is preserved, and the change is limited to the post-creation state-deletion path — for contracts that were not created in the current transaction, SELFDESTRUCT becomes a balance-transfer instruction. The narrowed semantics have been live on Ethereum mainnet since the Dencun activation in March 2024 with no recorded production incidents tied to the change.

No fee-market change: Bastion does not alter base fees, blob fees, or calldata gas, consistent with Mystique’s position on EIP-1559 and ETC’s monetary policy (ECIP-1017).

Implementation

To be completed. Reference implementations will be linked from the respective Ethereum Classic execution clients as the change set is developed. Each included EIP already has reference implementations in the upstream Ethereum execution-layer clients, listed in the Specification section above.

Copyright and related rights waived via CC0.