Ethereum Mainnet EVM Compatibility Specification

Overview

This document provides a comprehensive analysis of the Ethereum Improvement Proposals (EIPs), VM opcodes, and protocol features required for Fukuii to claim full Ethereum mainnet execution client compatibility. Fukuii was originally designed as an Ethereum Classic client, and this specification identifies the gaps and requirements for Ethereum mainnet compatibility.

Table of Contents

1. Current Implementation Status
2. Implemented EIPs
3. Ethereum Mainnet Fork History
4. Missing EIPs for Full Compatibility
5. Opcode Implementation Status
6. Precompiled Contracts
7. Consensus and Protocol Differences
8. Testing and Validation
9. Implementation Roadmap

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Current Implementation Status

Summary

Category	Implemented	Partial	Missing
Pre-Merge EIPs	25+	2	8+
Post-Merge EIPs	0	0	10+
Pectra/Fusaka EIPs	0	0	9
Opcodes	142/145	0	3
Precompiled Contracts	9/19	0	10

Compatibility Level

• ETC Spiral (≈ Shanghai equivalent): ✅ Full compatibility
• Ethereum Berlin: ✅ Full compatibility
• Ethereum London: ⚠️ Partial (EIP-1559 not implemented)
• Ethereum Paris (The Merge): ❌ Not implemented
• Ethereum Shanghai: ⚠️ Partial (beacon chain features missing)
• Ethereum Cancun (Dencun): ❌ Not implemented
• Ethereum Prague (Pectra/Fusaka): ❌ Not implemented

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Implemented EIPs

Frontier Era (Block 0)

EIP	Title	Status	Notes
N/A	Initial EVM opcodes	✅ Implemented	130+ base opcodes

Homestead (Block 1,150,000)

EIP	Title	Status	Notes
EIP-2	Homestead Hard-fork Changes	✅ Implemented	Contract creation, tx validation
EIP-7	DELEGATECALL	✅ Implemented	Opcode 0xF4
EIP-8	devp2p Forward Compatibility	✅ Implemented	Network protocol

Tangerine Whistle (Block 2,463,000)

EIP	Title	Status	Notes
EIP-150	Gas cost changes for IO-heavy operations	✅ Implemented	EXTCODE*, CALL*, SLOAD updates

Spurious Dragon (Block 2,675,000)

EIP	Title	Status	Notes
EIP-155	Simple replay attack protection	✅ Implemented	Chain ID in tx signature
EIP-160	EXP cost increase	✅ Implemented	G_expbyte = 50
EIP-161	State trie clearing	✅ Implemented	noEmptyAccounts flag
EIP-170	Contract code size limit	✅ Implemented	MAX_CODE_SIZE = 24576

Byzantium (Block 4,370,000)

EIP	Title	Status	Notes
EIP-100	Difficulty adjustment	✅ Implemented	Uncle inclusion adjustment
EIP-140	REVERT instruction	✅ Implemented	Opcode 0xFD
EIP-196	BN128 addition and multiplication	✅ Implemented	Precompiles at 0x06, 0x07
EIP-197	BN128 pairing check	✅ Implemented	Precompile at 0x08
EIP-198	Big integer modular exponentiation	✅ Implemented	Precompile at 0x05
EIP-211	RETURNDATASIZE and RETURNDATACOPY	✅ Implemented	Opcodes 0x3D, 0x3E
EIP-214	STATICCALL	✅ Implemented	Opcode 0xFA
EIP-649	Difficulty bomb delay	✅ Implemented	Block reward reduction
EIP-658	Transaction status in receipts	✅ Implemented	Status field in receipts

Constantinople/Petersburg (Block 7,280,000)

EIP	Title	Status	Notes
EIP-145	Bitwise shifting	✅ Implemented	SHL, SHR, SAR opcodes
EIP-1014	Skinny CREATE2	✅ Implemented	Opcode 0xF5
EIP-1052	EXTCODEHASH	✅ Implemented	Opcode 0x3F
EIP-1234	Constantinople bomb delay	✅ Implemented	Block reward = 2 ETH
EIP-1283	Net gas metering for SSTORE	✅ Implemented	Constantinople only

Istanbul (Block 9,069,000)

EIP	Title	Status	Notes
EIP-152	Blake2b F compression	✅ Implemented	Precompile at 0x09
EIP-1108	BN128 gas cost reduction	✅ Implemented	Reduced gas for BN128 ops
EIP-1344	ChainID opcode	✅ Implemented	Opcode 0x46
EIP-1884	Opcode repricing	✅ Implemented	SLOAD, BALANCE, EXTCODEHASH
EIP-2028	Calldata gas reduction	✅ Implemented	G_txdatanonzero = 16
EIP-2200	SSTORE gas changes (net metering)	✅ Implemented	Combined with EIP-1283

Berlin (Block 12,244,000)

EIP	Title	Status	Notes
EIP-2565	ModExp gas cost	✅ Implemented	Repriced modular exponentiation
EIP-2718	Typed Transaction Envelope	⚠️ Partial	Type 0 legacy only
EIP-2929	Gas cost increases for state access	✅ Implemented	Cold/warm access tracking
EIP-2930	Optional access lists	⚠️ Partial	Access lists parsed but Type 1 tx incomplete

London (Block 12,965,000)

EIP	Title	Status	Notes
EIP-1559	Fee market change	❌ Missing	Base fee, priority fee
EIP-3198	BASEFEE opcode	❌ Missing	Opcode 0x48
EIP-3529	Reduce refunds	✅ Implemented	SELFDESTRUCT refund = 0
EIP-3541	Reject new contracts starting with 0xEF	✅ Implemented	EOF preparation

Paris/The Merge (Block 15,537,394)

EIP	Title	Status	Notes
EIP-3675	Upgrade consensus to Proof-of-Stake	❌ Missing	Beacon chain integration
EIP-4399	DIFFICULTY → PREVRANDAO	❌ Missing	Opcode behavior change

Shanghai (Block 17,034,870)

EIP	Title	Status	Notes
EIP-3651	Warm COINBASE	✅ Implemented	Coinbase in warm addresses
EIP-3855	PUSH0 instruction	✅ Implemented	Opcode 0x5F
EIP-3860	Limit and meter initcode	✅ Implemented	MAX_INITCODE_SIZE
EIP-4895	Beacon chain push withdrawals	❌ Missing	Validator withdrawals
EIP-6049	Deprecate SELFDESTRUCT	✅ Implemented	Informational only

Cancun (Block 19,426,587)

EIP	Title	Status	Notes
EIP-1153	Transient storage opcodes	❌ Missing	TLOAD, TSTORE
EIP-4788	Beacon block root in EVM	❌ Missing	Parent beacon root
EIP-4844	Shard Blob Transactions	❌ Missing	Proto-danksharding
EIP-5656	MCOPY instruction	❌ Missing	Memory copy opcode
EIP-6780	SELFDESTRUCT changes	❌ Missing	Same-transaction only
EIP-7516	BLOBBASEFEE opcode	❌ Missing	Blob gas price

Prague/Pectra (Execution: Prague, Consensus: Fusaka - Activated May 7, 2025)

Note: EIP-7251 and EIP-7549 appear in both sections as they affect both execution and consensus layers.

EIP	Title	Status	Notes
Execution Layer EIPs
EIP-2537	BLS12-381 precompiles	❌ Missing	BLS curve operations (9 precompiles)
EIP-2935	Serve historical block hashes from state	❌ Missing	BLOCKHASH opcode improvement
EIP-6110	Supply validator deposits on chain	❌ Missing	Deposit processing in EL
EIP-7002	Execution layer triggerable exits	❌ Missing	Validator exits from EL
EIP-7251	Increase MAX_EFFECTIVE_BALANCE	❌ Missing	Max 2048 ETH effective balance
EIP-7549	Move committee index outside Attestation	❌ Missing	Consensus layer optimization
EIP-7685	General purpose execution layer requests	❌ Missing	Request framework
EIP-7702	Set EOA account code for one transaction	❌ Missing	Account abstraction precursor
Consensus Layer EIPs (Fusaka)
EIP-7251	Max effective balance (Consensus)	❌ Missing	Validator consolidation support
EIP-7549	Committee index optimization	❌ Missing	Attestation efficiency
EIP-7594	PeerDAS (Peer Data Availability Sampling)	❌ Missing	Data availability layer

---

Ethereum Mainnet Fork History

Block 0          │ Frontier
Block 200,000    │ Frontier Thawing
Block 1,150,000  │ Homestead
Block 1,920,000  │ DAO Fork (ETC split)
Block 2,463,000  │ Tangerine Whistle
Block 2,675,000  │ Spurious Dragon
Block 4,370,000  │ Byzantium
Block 7,280,000  │ Constantinople/Petersburg
Block 9,069,000  │ Istanbul
Block 9,200,000  │ Muir Glacier
Block 12,244,000 │ Berlin
Block 12,965,000 │ London          ← EIP-1559 (base fee)
Block 13,773,000 │ Arrow Glacier
Block 15,050,000 │ Gray Glacier
Block 15,537,394 │ Paris (The Merge) ← PoS transition
Block 17,034,870 │ Shanghai        ← Withdrawals
Block 19,426,587 │ Cancun (Dencun) ← Proto-danksharding
Slot 10388992    │ Prague (Pectra/Fusaka) ← Account abstraction, MaxEB, EL requests
(May 7, 2025)    │ (Execution: Prague, Consensus: Fusaka)

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Missing EIPs for Full Compatibility

Critical Path (Required for Basic Compatibility)

1. EIP-1559: Fee Market Change for ETH 1.0 Chain

Priority: 🔴 Critical
Complexity: High
Impact: Transaction processing, block validation

Requirements: - Add base_fee_per_gas to block header - Add max_fee_per_gas and max_priority_fee_per_gas to transactions - Implement Type 2 (EIP-1559) transactions - Calculate effective gas price - Burn base fee portion - Implement base fee adjustment algorithm

Gas Calculation:

effective_gas_price = min(max_fee_per_gas, base_fee_per_gas + max_priority_fee_per_gas)
priority_fee = effective_gas_price - base_fee_per_gas

2. EIP-3198: BASEFEE Opcode

Priority: 🔴 Critical (depends on EIP-1559)
Complexity: Low
Impact: EVM opcode

Implementation:

case object BASEFEE extends ConstOp(0x48)(s => UInt256(s.env.blockHeader.baseFee.getOrElse(0)))

3. EIP-4399: Supplant DIFFICULTY with PREVRANDAO

Priority: 🔴 Critical (post-Merge)
Complexity: Low
Impact: DIFFICULTY opcode behavior

Changes: - After The Merge, DIFFICULTY (0x44) returns the beacon chain RANDAO value - Rename to PREVRANDAO semantically - Update block header to include prevRandao field

4. EIP-3675: Upgrade Consensus to Proof-of-Stake

Priority: 🔴 Critical (for mainnet sync)
Complexity: Very High
Impact: Consensus, block production

Requirements: - Engine API implementation (JSON-RPC for consensus/execution layer communication) - Block building without PoW - Beacon chain integration - Fork choice rule changes - Terminal Total Difficulty (TTD) handling

High Priority (Required for Modern Features)

5. EIP-4895: Beacon Chain Push Withdrawals

Priority: 🟠 High
Complexity: Medium
Impact: Block processing

Requirements: - Add withdrawals field to block body - Process withdrawals as balance credits - Withdrawal index tracking

6. EIP-1153: Transient Storage Opcodes

Priority: 🟠 High
Complexity: Medium
Impact: EVM opcodes

New Opcodes: | Opcode | Name | Description | |--------|------|-------------| | 0x5C | TLOAD | Load from transient storage | | 0x5D | TSTORE | Store to transient storage |

Implementation Notes: - Transient storage is cleared at end of transaction - Same gas costs as SLOAD/SSTORE warm access (100 gas) - Per-transaction, per-address key-value store

7. EIP-5656: MCOPY Instruction

Priority: 🟠 High
Complexity: Low
Impact: EVM opcode

New Opcode: | Opcode | Name | Description | |--------|------|-------------| | 0x5E | MCOPY | Memory copy |

Gas Calculation:

gas = G_verylow + G_copy * ceil(size / 32) + memory_expansion_cost

8. EIP-6780: SELFDESTRUCT Only in Same Transaction

Priority: 🟠 High
Complexity: Medium
Impact: SELFDESTRUCT behavior

Changes: - SELFDESTRUCT only deletes the account if called in the same transaction as contract creation - Otherwise, only transfers ETH, does not delete code or storage - Enables future state expiry proposals

Medium Priority (Required for Complete Compliance)

9. EIP-4844: Shard Blob Transactions

Priority: 🟡 Medium
Complexity: Very High
Impact: Transaction types, data availability

Requirements: - Type 3 (blob) transactions - KZG commitments and proofs - Blob data handling - Data availability sampling (future)

New Components: - blob_versioned_hashes in transactions - excess_blob_gas and blob_gas_used in headers - Precompile at 0x0A (point evaluation)

10. EIP-7516: BLOBBASEFEE Opcode

Priority: 🟡 Medium (depends on EIP-4844)
Complexity: Low
Impact: EVM opcode

New Opcode: | Opcode | Name | Description | |--------|------|-------------| | 0x4A | BLOBBASEFEE | Get blob base fee |

11. EIP-4788: Beacon Block Root in EVM

Priority: 🟡 Medium
Complexity: Medium
Impact: System contract

Requirements: - System contract at address 0x000F3df6D732807Ef1319fB7B8bB8522d0Beac02 - Stores beacon block roots - Ring buffer of 8191 entries

Lower Priority (Future Enhancements)

12. EIP-2537: BLS12-381 Curve Operations

Priority: 🟠 High (Included in Pectra)
Complexity: High
Impact: Precompiled contracts

New Precompiles: | Address | Name | Description | |---------|------|-------------| | 0x0B | BLS12_G1ADD | G1 point addition | | 0x0C | BLS12_G1MUL | G1 point multiplication | | 0x0D | BLS12_G1MSM | G1 multi-scalar multiplication | | 0x0E | BLS12_G2ADD | G2 point addition | | 0x0F | BLS12_G2MUL | G2 point multiplication | | 0x10 | BLS12_G2MSM | G2 multi-scalar multiplication | | 0x11 | BLS12_PAIRING | Pairing check | | 0x12 | BLS12_MAP_FP_TO_G1 | Hash to G1 | | 0x13 | BLS12_MAP_FP2_TO_G2 | Hash to G2 |

Notes: - Required for efficient BLS signature verification in EVM - Critical for Ethereum consensus layer integration - Activated as part of Pectra/Fusaka (May 7, 2025)

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Prague/Pectra (Fusaka) EIPs - Activated May 7, 2025

13. EIP-2935: Serve Historical Block Hashes from State

Priority: 🟡 Medium
Complexity: Medium
Impact: State storage, BLOCKHASH opcode

Requirements: - System contract at address 0x0aae40965e6800cd9b1f4b05ff21581047e3f91e - Stores last 8192 block hashes in a ring buffer - BLOCKHASH opcode reads from this contract for blocks beyond 256 - Improves historical block hash availability

Implementation Details:

HISTORY_STORAGE_ADDRESS = 0x0aae40965e6800cd9b1f4b05ff21581047e3f91e
HISTORY_SERVE_WINDOW = 8192

Gas Impact: - BLOCKHASH becomes more expensive for historical queries - But provides much longer lookback window

14. EIP-6110: Supply Validator Deposits on Chain

Priority: 🔴 Critical (Execution-Consensus Integration)
Complexity: High
Impact: Deposit contract, block structure

Requirements: - Process deposit events from deposit contract in execution layer - Add deposits field to execution payload - Remove reliance on consensus layer for deposit processing - Maximum 8192 deposits per block

Deposit Contract: 0x00000000219ab540356cBB839Cbe05303d7705Fa

Implementation Notes: - Deposits are extracted from logs in execution layer - Improves execution-consensus layer separation - Part of Engine API v4

15. EIP-7002: Execution Layer Triggerable Exits

Priority: 🟠 High
Complexity: Medium
Impact: Validator exits, block structure

Requirements: - System contract at 0x00431D736Ab7fA9C4d1B0e70c1E2B8a0e79e3C4e - Allows validators to trigger exits from execution layer - Add exits field to execution payload - Maximum 16 exits per block

Exit Request Structure:

case class ExitRequest(
  validatorPubkey: ByteString,  // 48 bytes
  amount: BigInt                 // uint64 value (represented as BigInt in Scala)
)

16. EIP-7251: Increase MAX_EFFECTIVE_BALANCE

Priority: 🟡 Medium (Consensus Layer)
Complexity: Medium
Impact: Validator economics, consolidations

Changes: - Increases MAX_EFFECTIVE_BALANCE from 32 ETH to 2048 ETH - Allows validator consolidation - Reduces beacon chain state size - Execution layer needs to support consolidation requests

Impact on Execution Layer: - Must support validator consolidation requests - Part of general request framework (EIP-7685)

17. EIP-7549: Move Committee Index Outside Attestation

Priority: 🟢 Lower (Consensus Layer)
Complexity: Low
Impact: Attestation structure

Notes: - Primarily consensus layer change - Improves attestation efficiency - No direct execution layer impact - Minimal execution client changes required

18. EIP-7685: General Purpose Execution Layer Requests

Priority: 🔴 Critical
Complexity: Medium
Impact: Block structure, Engine API

Requirements: - Framework for execution layer to consensus layer requests - Add requests field to execution payload - Support multiple request types (deposits, exits, consolidations)

Request Types: | Type ID | Name | EIP | |---------|------|-----| | 0x00 | Deposit | EIP-6110 | | 0x01 | Exit | EIP-7002 | | 0x02 | Consolidation | EIP-7251 |

Implementation:

case class ExecutionPayload(
  // ... existing fields ...
  requests: Seq[Request]  // New field
)

sealed trait Request {
  def requestType: Byte
}

19. EIP-7702: Set EOA Account Code for One Transaction

Priority: 🔴 Critical
Complexity: High
Impact: Transaction types, account abstraction

Requirements: - Implement Type 4 (EIP-7702) transactions - Add authorization_list to transactions - Temporarily set code for EOA accounts during transaction - Revert code after transaction completes

Authorization Structure:

case class Authorization(
  chainId: BigInt,
  address: Address,
  nonce: BigInt,
  yParity: Byte,
  r: BigInt,
  s: BigInt
)

Transaction Format: - Type: 0x04 - Fields: 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

Use Cases: - Account abstraction without protocol changes - Batched transactions from EOAs - Sponsored transactions - Gas payment by contract

Implementation Challenges: - Temporary code storage - Nonce management - Gas accounting - Security considerations (reentrancy, etc.)

20. EIP-7594: PeerDAS (Peer Data Availability Sampling)

Priority: 🟢 Lower (Consensus Layer)
Complexity: Very High
Impact: Data availability, networking

Notes: - Primarily consensus layer feature - Improves data availability sampling - Reduces bandwidth requirements for validators - Minimal direct execution client impact - Enables more efficient blob handling

---

Opcode Implementation Status

Complete Implementation (142 opcodes)

Arithmetic Operations (0x00-0x0B)

Opcode	Name	Gas	Status
0x00	STOP	0	✅
0x01	ADD	3	✅
0x02	MUL	5	✅
0x03	SUB	3	✅
0x04	DIV	5	✅
0x05	SDIV	5	✅
0x06	MOD	5	✅
0x07	SMOD	5	✅
0x08	ADDMOD	8	✅
0x09	MULMOD	8	✅
0x0A	EXP	10*	✅
0x0B	SIGNEXTEND	5	✅

Comparison & Bitwise Logic (0x10-0x1D)

Opcode	Name	Gas	Status
0x10	LT	3	✅
0x11	GT	3	✅
0x12	SLT	3	✅
0x13	SGT	3	✅
0x14	EQ	3	✅
0x15	ISZERO	3	✅
0x16	AND	3	✅
0x17	OR	3	✅
0x18	XOR	3	✅
0x19	NOT	3	✅
0x1A	BYTE	3	✅
0x1B	SHL	3	✅
0x1C	SHR	3	✅
0x1D	SAR	3	✅

SHA3 (0x20)

Opcode	Name	Gas	Status
0x20	SHA3	30*	✅

Environmental Information (0x30-0x3F)

Opcode	Name	Gas	Status
0x30	ADDRESS	2	✅
0x31	BALANCE	100-2600*	✅
0x32	ORIGIN	2	✅
0x33	CALLER	2	✅
0x34	CALLVALUE	2	✅
0x35	CALLDATALOAD	3	✅
0x36	CALLDATASIZE	2	✅
0x37	CALLDATACOPY	3*	✅
0x38	CODESIZE	2	✅
0x39	CODECOPY	3*	✅
0x3A	GASPRICE	2	✅
0x3B	EXTCODESIZE	100-2600*	✅
0x3C	EXTCODECOPY	100-2600*	✅
0x3D	RETURNDATASIZE	2	✅
0x3E	RETURNDATACOPY	3*	✅
0x3F	EXTCODEHASH	100-2600*	✅

Block Information (0x40-0x48)

Opcode	Name	Gas	Status	Notes
0x40	BLOCKHASH	20	✅
0x41	COINBASE	2	✅
0x42	TIMESTAMP	2	✅
0x43	NUMBER	2	✅
0x44	DIFFICULTY/PREVRANDAO	2	⚠️	Returns difficulty, not prevRandao
0x45	GASLIMIT	2	✅
0x46	CHAINID	2	✅
0x47	SELFBALANCE	5	✅
0x48	BASEFEE	2	❌	EIP-1559 required

Stack, Memory, Storage, Flow Operations (0x50-0x5F)

Opcode	Name	Gas	Status
0x50	POP	2	✅
0x51	MLOAD	3*	✅
0x52	MSTORE	3*	✅
0x53	MSTORE8	3*	✅
0x54	SLOAD	100-2100*	✅
0x55	SSTORE	100-20000*	✅
0x56	JUMP	8	✅
0x57	JUMPI	10	✅
0x58	PC	2	✅
0x59	MSIZE	2	✅
0x5A	GAS	2	✅
0x5B	JUMPDEST	1	✅
0x5C	TLOAD	100	❌
0x5D	TSTORE	100	❌
0x5E	MCOPY	3*	❌
0x5F	PUSH0	2	✅

Push Operations (0x60-0x7F)

All PUSH1-PUSH32 opcodes: ✅ Implemented

Dup Operations (0x80-0x8F)

All DUP1-DUP16 opcodes: ✅ Implemented

Swap Operations (0x90-0x9F)

All SWAP1-SWAP16 opcodes: ✅ Implemented

Log Operations (0xA0-0xA4)

All LOG0-LOG4 opcodes: ✅ Implemented

System Operations (0xF0-0xFF)

Opcode	Name	Gas	Status
0xF0	CREATE	32000*	✅
0xF1	CALL	100-2600*	✅
0xF2	CALLCODE	100-2600*	✅
0xF3	RETURN	0*	✅
0xF4	DELEGATECALL	100-2600*	✅
0xF5	CREATE2	32000*	✅
0xFA	STATICCALL	100-2600*	✅
0xFD	REVERT	0*	✅
0xFE	INVALID	all gas	✅
0xFF	SELFDESTRUCT	5000*	⚠️

Missing Opcodes Summary

Opcode	Name	EIP	Priority
0x48	BASEFEE	EIP-3198	🔴 Critical
0x4A	BLOBBASEFEE	EIP-7516	🟡 Medium
0x5C	TLOAD	EIP-1153	🟠 High
0x5D	TSTORE	EIP-1153	🟠 High
0x5E	MCOPY	EIP-5656	🟠 High

---

Precompiled Contracts

Implemented Precompiles

Address	Name	EIP	Status
0x01	ECRECOVER	Frontier	✅
0x02	SHA256	Frontier	✅
0x03	RIPEMD160	Frontier	✅
0x04	IDENTITY	Frontier	✅
0x05	MODEXP	EIP-198/2565	✅
0x06	BN128ADD	EIP-196	✅
0x07	BN128MUL	EIP-196	✅
0x08	BN128PAIRING	EIP-197	✅
0x09	BLAKE2F	EIP-152	✅

Missing Precompiles

Address	Name	EIP	Priority
0x0A	KZG_POINT_EVALUATION	EIP-4844	🟡 Medium
0x0B	BLS12_G1ADD	EIP-2537	🟠 High (Pectra)
0x0C	BLS12_G1MUL	EIP-2537	🟠 High (Pectra)
0x0D	BLS12_G1MSM	EIP-2537	🟠 High (Pectra)
0x0E	BLS12_G2ADD	EIP-2537	🟠 High (Pectra)
0x0F	BLS12_G2MUL	EIP-2537	🟠 High (Pectra)
0x10	BLS12_G2MSM	EIP-2537	🟠 High (Pectra)
0x11	BLS12_PAIRING	EIP-2537	🟠 High (Pectra)
0x12	BLS12_MAP_FP_TO_G1	EIP-2537	🟠 High (Pectra)
0x13	BLS12_MAP_FP2_TO_G2	EIP-2537	🟠 High (Pectra)

---

Transaction Types

Ethereum has evolved from a single transaction format to multiple typed transactions using the envelope format (EIP-2718). Fukuii currently only supports Type 0 (legacy) transactions.

Type 0: Legacy Transactions (Pre-EIP-2718)

Status: ✅ Implemented
EIP: N/A (Original format)

Structure:

rlp([nonce, gasPrice, gasLimit, to, value, data, v, r, s])

Fields: - nonce: Transaction counter for sender - gasPrice: Gas price in wei - gasLimit: Maximum gas allowed - to: Recipient address (or empty for contract creation) - value: ETH amount to transfer - data: Contract data or initialization code - v, r, s: ECDSA signature components

Limitations: - Fixed gas price (no priority fee) - No access lists - No chain ID protection in pre-EIP-155 transactions

Type 1: Access List Transactions (EIP-2930)

Status: ⚠️ Partial (Berlin)
EIP: EIP-2930

Structure:

0x01 || rlp([chainId, nonce, gasPrice, gasLimit, to, value, data, accessList, signatureYParity, signatureR, signatureS])

New Fields: - accessList: List of addresses and storage keys that will be accessed - Transaction type prefix: 0x01

Benefits: - Reduced gas costs for pre-declared storage access - Mitigates effects of EIP-2929 (cold/warm access costs)

Type 2: EIP-1559 Transactions

Status: ❌ Missing (London)
EIP: EIP-1559

Structure:

0x02 || rlp([chainId, nonce, maxPriorityFeePerGas, maxFeePerGas, gasLimit, to, value, data, accessList, signatureYParity, signatureR, signatureS])

New Fields: - maxPriorityFeePerGas: Maximum priority fee (tip) to miner - maxFeePerGas: Maximum total fee willing to pay - Replaces gasPrice with fee market mechanism

Gas Calculation:

effectiveGasPrice = min(maxFeePerGas, baseFeePerGas + maxPriorityFeePerGas)
priorityFee = effectiveGasPrice - baseFeePerGas

Benefits: - Predictable base fees - Better UX (no more gas price guessing) - ETH burn mechanism (base fee is burned)

Type 3: Blob Transactions (EIP-4844)

Status: ❌ Missing (Cancun/Dencun)
EIP: EIP-4844

Structure:

0x03 || rlp([chainId, nonce, maxPriorityFeePerGas, maxFeePerGas, gasLimit, to, value, data, accessList, maxFeePerBlobGas, blobVersionedHashes, signatureYParity, signatureR, signatureS])

New Fields: - maxFeePerBlobGas: Maximum fee per blob gas unit - blobVersionedHashes: Commitments to blob data (not included in block)

Blob Data: - Blobs are ~128KB each (4096 field elements × 32 bytes) - Not stored in execution layer state - Designed for rollup data availability - Separate gas market from regular transactions

Benefits: - Dramatically cheaper data availability for rollups - Separate blob gas pricing (independent of regular gas) - Temporary storage (blobs pruned after ~18 days)

Type 4: Account Abstraction Transactions (EIP-7702)

Status: ❌ Missing (Pectra/Fusaka)
EIP: EIP-7702

Structure:

0x04 || rlp([chainId, nonce, maxPriorityFeePerGas, maxFeePerGas, gasLimit, to, value, data, accessList, authorizationList, signatureYParity, signatureR, signatureS])

New Field: - authorizationList: List of authorizations to temporarily set code for EOAs

Authorization Structure:

case class Authorization(
  chainId: BigInt,
  address: Address,      // Contract address to delegate to
  nonce: BigInt,         // Account nonce for replay protection
  yParity: Byte,
  r: BigInt,
  s: BigInt
)

Mechanism: 1. EOA signs authorization to delegate to a contract 2. During transaction execution, EOA temporarily gets code from contract 3. Code is removed after transaction completes 4. Enables smart contract logic for EOAs

Benefits: - Account abstraction for EOAs without protocol changes - Batched transactions from EOAs - Gas sponsorship (someone else pays gas) - Custom signature schemes - Social recovery - Transaction batching

Security Considerations: - Authorization nonce prevents replay attacks - Chain ID prevents cross-chain replay - Temporary delegation limits attack surface - Must validate all authorizations before execution

Transaction Type Comparison

Feature	Type 0	Type 1	Type 2	Type 3	Type 4
Gas Pricing	Fixed	Fixed	Dynamic (EIP-1559)	Dynamic + Blob	Dynamic + Blob
Access Lists	❌	✅	✅	✅	✅
Base Fee	❌	❌	✅	✅	✅
Blob Data	❌	❌	❌	✅	❌
EOA Code Delegation	❌	❌	❌	❌	✅
Chain ID	Optional	✅	✅	✅	✅
Use Case	Legacy	Gas optimization	Modern txs	Rollup data	Account abstraction

Implementation Status in Fukuii

Type	Status	Priority	Notes
Type 0	✅ Implemented	N/A	Fully supported
Type 1	⚠️ Partial	🟠 High	Access list parsing incomplete
Type 2	❌ Missing	🔴 Critical	Required for London compatibility
Type 3	❌ Missing	🟡 Medium	Required for Cancun compatibility
Type 4	❌ Missing	🔴 Critical	Required for Pectra compatibility

---

Consensus and Protocol Differences

Ethereum Classic vs Ethereum Mainnet

Feature	Ethereum Classic	Ethereum Mainnet
Consensus	Proof of Work (Ethash)	Proof of Stake
Block Time	~13 seconds	12 seconds (slots)
Block Reward	2.56 ETC (w/ reduction)	N/A (tips only)
Difficulty Bomb	Removed	N/A (post-Merge)
DAO Fork	Not applied	Applied
EIP-1559	Not implemented	Implemented
Beacon Chain	Not applicable	Required
Withdrawals	Not applicable	EIP-4895
Blob Transactions	Not applicable	EIP-4844

Key Protocol Differences

1. Transaction Types:
2. ETC: Type 0 (legacy) only

3. ETH: Types 0, 1, 2, 3, 4 (legacy, access list, EIP-1559, blob, EIP-7702)

4. Block Headers:

5. ETC: Classic header structure with PoW fields

6. ETH: Extended header with baseFeePerGas, withdrawalsRoot, blobGasUsed, excessBlobGas, parentBeaconBlockRoot

7. Execution Payload (Post-Pectra):

8. Additional field: requests (EIP-7685)

9. Includes deposits, exits, and consolidation requests

10. Chain ID:

11. ETC: 61 (mainnet), 63 (Mordor)

12. ETH: 1 (mainnet)

13. Network Protocol:

14. ETC: eth/63-68, snap/1

15. ETH: eth/66-68, snap/1 (with extended message types)

16. Validator Operations (Pectra):

17. ETC: N/A (PoW)
18. ETH: On-chain deposits (EIP-6110), execution-triggered exits (EIP-7002), validator consolidation (EIP-7251)

---

Testing and Validation

Ethereum Test Suite Compatibility

Fukuii includes the ethereum/tests submodule for compliance testing:

# Run EVM tests
sbt "testOnly *VMSpec"
sbt "Evm / test"

# Run blockchain tests
sbt "IntegrationTest / test"

Test Categories

Category	Status	Notes
General State Tests	✅ Passing	Core EVM tests
Blockchain Tests	✅ Passing	Pre-Merge blocks
VM Tests	✅ Passing	Opcode tests
RLP Tests	✅ Passing	Encoding tests
Transaction Tests	⚠️ Partial	Type 0 only
Beacon Chain Tests	❌ Missing	Post-Merge

Recommended Validation Steps

1. EVM Compliance:

   # Run ethereum/tests GeneralStateTests
   sbt "testOnly *GeneralStateTest*"
   

2. Opcode Correctness:

   # Run VM-specific tests
   sbt "testOnly *OpCode*"
   

3. Precompile Verification:

   # Run precompiled contract tests
   sbt "testOnly *PrecompiledContracts*"
   

4. Fork Transition Testing:

   # Test fork activation
   sbt "testOnly *Fork*"
   

---

Implementation Roadmap

Phase 1: EIP-1559 Support (Estimated: 4-6 weeks)

1. Week 1-2: Transaction type infrastructure
2. Implement typed transaction envelope (EIP-2718)
3. Add Type 1 (EIP-2930) access list transactions

4. Add Type 2 (EIP-1559) transactions

5. Week 3-4: Block header changes

6. Add baseFeePerGas to block header
7. Implement base fee calculation algorithm

8. Update block validation

9. Week 5-6: EVM changes

10. Implement BASEFEE opcode (EIP-3198)
11. Update gas price calculations
12. Integration testing

Phase 2: Missing Cancun EIPs (Estimated: 3-4 weeks)

1. Week 1: Transient storage (EIP-1153)
2. Implement TLOAD/TSTORE opcodes

3. Add transient storage tracking per transaction

4. Week 2: MCOPY instruction (EIP-5656)

5. Implement memory copy opcode

6. Gas cost calculations

7. Week 3: SELFDESTRUCT changes (EIP-6780)

8. Modify SELFDESTRUCT behavior

9. Track contract creation in same transaction

10. Week 4: Testing and validation

Phase 3: Post-Merge Infrastructure (Estimated: 8-12 weeks)

1. Weeks 1-4: Engine API
2. Implement JSON-RPC Engine API
3. Payload building and validation

4. Fork choice rule updates

5. Weeks 5-8: Beacon chain integration

6. PREVRANDAO support (EIP-4399)
7. Withdrawals processing (EIP-4895)

8. Parent beacon block root (EIP-4788)

9. Weeks 9-12: Testing and validation

10. Hive test suite integration
11. Devnet participation
12. Full sync testing

Phase 4: Proto-Danksharding (Estimated: 6-8 weeks)

1. Weeks 1-3: Blob transactions
2. Type 3 transaction support
3. KZG commitment handling

4. Point evaluation precompile

5. Weeks 4-6: Block changes

6. Blob gas accounting
7. Excess blob gas tracking

8. BLOBBASEFEE opcode

9. Weeks 7-8: Testing and validation

Phase 5: Pectra/Fusaka Support (Estimated: 10-14 weeks)

1. Weeks 1-3: BLS12-381 Precompiles (EIP-2537)
2. Implement 9 BLS12-381 precompiled contracts (0x0B - 0x13)
3. G1/G2 point operations
4. Pairing and mapping functions

5. Extensive testing with official test vectors

6. Weeks 4-5: Historical Block Hashes (EIP-2935)

7. Implement system contract for block hash storage
8. Update BLOCKHASH opcode logic

9. Ring buffer implementation (8192 blocks)

10. Weeks 6-8: Execution Layer Requests Framework (EIP-7685)

11. Add requests field to execution payload
12. Implement request encoding/decoding
13. Update Engine API to v4

14. Request validation and processing

15. Weeks 9-10: On-chain Deposits (EIP-6110)

16. Extract deposits from execution layer logs
17. Add deposits field to payload
18. Deposit validation (max 8192 per block)

19. Integration with deposit contract

20. Weeks 11-12: Execution-Triggered Exits (EIP-7002)

21. Implement exit request system contract
22. Add exits field to payload
23. Exit request validation (max 16 per block)

24. Public key and amount processing

25. Weeks 13-14: EIP-7702 Transactions (Type 4)

26. Authorization list parsing and validation
27. Temporary code delegation mechanism
28. Nonce verification for authorizations
29. Gas accounting for delegated code
30. Comprehensive security testing

Note on EIP-7251 and EIP-7549: These are primarily consensus layer changes with minimal execution layer impact beyond supporting consolidation requests in the general request framework.

Note on EIP-7594 (PeerDAS): This is a consensus layer networking change with no direct execution client implementation required.

---

Conclusion

Fukuii provides a solid foundation for EVM compatibility up to the Berlin/Istanbul level. To achieve full Ethereum mainnet compatibility including the recently activated Pectra/Fusaka fork (May 7, 2025), the following priorities should be addressed:

1. Critical: EIP-1559 and related London fork changes
2. Critical: Post-Merge infrastructure (Engine API, PoS)
3. Critical: Execution layer requests framework (EIP-7685)
4. Critical: Type 4 transactions and account abstraction (EIP-7702)
5. High: Missing Cancun opcodes (TLOAD, TSTORE, MCOPY)
6. High: BLS12-381 precompiles (EIP-2537) - now part of Pectra
7. High: On-chain deposits and execution-triggered exits (EIP-6110, EIP-7002)
8. Medium: Proto-danksharding (EIP-4844)
9. Medium: Historical block hashes (EIP-2935)

The architecture of Fukuii (based on the well-tested Mantis codebase) provides a clean separation between EVM execution and consensus, which should facilitate these additions. The Pectra/Fusaka fork represents a significant evolution of the Ethereum protocol, introducing important features for account abstraction, validator management, and execution-consensus layer integration.

Key Takeaways for Pectra/Fusaka

Execution Layer Changes: - EIP-7702 brings delegated code execution to EOAs, a major step toward account abstraction - EIP-2537 adds 9 new precompiles for BLS12-381 operations - EIP-2935 improves historical block hash availability - EIP-7685 establishes a general framework for execution-to-consensus requests

Execution-Consensus Integration: - EIP-6110 moves deposit processing to execution layer - EIP-7002 enables execution layer to trigger validator exits - EIP-7251 supports validator consolidation (minimal execution layer impact)

Development Impact: The Pectra fork significantly increases the complexity of Ethereum execution clients, particularly around: 1. Transaction type handling (Type 4) 2. System contract interactions (multiple new system contracts) 3. Engine API evolution (v4 with request support) 4. Cryptographic operations (BLS12-381)

Estimated Total Implementation Time: 30-44 weeks across 5 major phases, assuming sequential development. Parallel development could reduce this timeline significantly.

---

References

Official Ethereum Resources

• Ethereum EIPs Repository
• Ethereum Execution Specs
• EVM Opcodes Reference
• Ethereum Yellow Paper
• Ethereum/tests Repository

Ethereum Classic Resources

• ECIP Repository

Pectra/Fusaka Fork Resources

• Pectra Network Upgrade Meta
• EIP-2537: BLS12-381 Precompiles
• EIP-2935: Historical Block Hashes
• EIP-6110: On-chain Deposits
• EIP-7002: Execution Layer Exits
• EIP-7251: Max Effective Balance
• EIP-7549: Committee Index Optimization
• EIP-7594: PeerDAS
• EIP-7685: General Purpose EL Requests
• EIP-7702: Set Code for EOAs

Engine API and Consensus

• Engine API Specification
• Consensus Layer Specs

Testing and Validation

• Hive Testing Framework
• Execution Spec Tests

---

Document History

• Initial Version: Pre-Pectra analysis (focusing on London through Cancun)
• Current Version (December 2025): Updated for Pectra/Fusaka fork activation
• Pectra/Fusaka fork was activated on May 7, 2025
• Added 9 new Pectra/Fusaka EIPs with detailed analysis
• Added comprehensive transaction types section (Types 0-4)
• Updated fork history timeline with Pectra activation
• Revised priority classifications (EIP-2537 upgraded to High)
• Added 10 new precompile addresses (1 from EIP-4844, 9 from EIP-2537)
• Expanded implementation roadmap with Phase 5 (Pectra support)
• Enhanced conclusion with Pectra-specific development impact analysis
• Added comprehensive references for Pectra-related EIPs