EVM Compatibility

The eSpace implements an Ethereum Virtual Machine (EVM) with alignment to Ethereum's behavior through CIP-645. Below are some differences between eSpace and Ethereum:

Transaction Type

• eSpace initially only supports 155 type transaction (legacy transactions)
• EIP-2930 (type 1) & EIP-1559 (type 2) transactions are supported after hardfork v2.4.0.
• EIP-4844 (type 3) transactions are not supported.
• EIP-7702 (type 4) transactions are supported after hardfork v3.0.0.

EVM Opcodes

As of hardfork v3.0.0 (CIP-645), Conflux eSpace implements multiple Ethereum Improvement Proposals (EIPs) to align behavior with Ethereum's EVM:

Opcode-Specific Changes

• BLOBHASH and BLOBBASEFEE opcodes (EIP-4844) are implemented with consistent "zero" results

Block Time

The NUMBER opcode will return the tree-graph epoch number. As a result, block.number used in eSpace contracts will not grow at a stable and predictable rate, and so it might not be suitable for measuring time.

Block generate rate is 1.25s per block (mainnet), is same as Core Space Epoch time.

Contract Size

Contract max code size is 49152 (double as Ethereum).

Transaction Fees

Storage-Related Gas Costs

Due to Conflux's storage collateral mechanism and high-performance design, storage-related operations have adjusted gas costs (doubled from Ethereum's values):

1. SSTORE: 40000 gas (instead of 20000 gas in Ethereum) when changing a storage entry from zero to non-zero
2. Contract deployment: Each byte costs 400 gas (instead of 200 gas in Ethereum)
3. EIP-7702 PER_EMPTY_ACCOUNT_COUNT: 50000 gas (instead of 25000 gas in Ethereum)

Gas Refunds

• Gas refund cap: In Ethereum, if a transaction's gas limit exceeds the actual gas cost, the remaining gas is fully refunded. In contrast, Conflux refunds a maximum of 1/4 of the gas limit. Check Gas Limit, Gas Used, and Gas Charged for more details.
• EIP-7702 refund difference: When updating delegate addresses (rather than creating a new delegation), Conflux does not issue the 12500 gas refund that Ethereum provides.

BLOCKHASH Gas Pricing

Conflux supports querying a larger range of blocks [n-65535, n] compared to Ethereum's [n-256, n-1]. Corresponding gas prices for BLOCKHASH are adjusted as follows:

• Ethereum: 20 gas (uniform for all cases)
• Conflux: 2100 gas (for the range [n-65535, n-257]), 100 gas (for blocks in [n-256, n-1])

Transaction Gas limit

• Only blocks whose height is a multiple of 5 can include Ethereum-type transactions. The total gas limit of these transactions cannot exceed half of the block gas limit, which is 30 million gas.
• A transaction's gas limit should be no less than 100 times the byte size of its call data. Check CIP-130 for more details.

COINBASE Address Handling

The COINBASE opcode returns a hex20 address corresponding to Core Space rather than eSpace. The eSpace address with the same hex20 value is not considered "warm" per EIP-2929.

Transaction Balance Handling

When transaction balance cannot afford maximum cost (max gas price × gas limit + tx value):

• Ethereum: Transaction fails without nonce increment or fee deduction
• Conflux: Nonce is incremented and maximum effective gas price × gas limit is deducted (or entire balance if insufficient)

The maximum effective gas price equals to gasPrice if gasPrice is specified otherwise min(maxFeePerGas, baseFeePerGas+maxPriorityFeePerGas).

EVM Precompiles

All standard precompiles are supported.

Address	ID	Name	Spec	Status	Version
0x01	ECRecover	ECDSA public key recovery	Yellow Paper	✅
0x02	SHA256	SHA-2 256-bit hash function	Yellow Paper	✅
0x03	RIPEMD160	RIPEMD 160-bit hash function	Yellow Paper	✅
0x04	Identity	Identity function	Yellow Paper	✅
0x05	ModExp	Big integer modular exponentiation	EIP-198	✅
0x06	BN128Add	Elliptic curve addition	EIP-196	✅
0x07	BN128Mul	Elliptic curve scalar multiplication	EIP-196	✅
0x08	BN128Pair	Elliptic curve pairing check	EIP-197	✅
0x09	Blake2F	BLAKE2b F compression function	EIP-152	✅
0x0a	PointEvaluation	Verify p(z) = y given commitment that corresponds to the polynomial p(x) and a KZG proof	EIP-4844	✅	V2.4.0
0x0b	BLS12_G1ADD	BLS12-381 G1 addition	EIP-2537	✅	V3.0.0
0x0c	BLS12_G1MSM	BLS12-381 G1 multi-scalar multiplication	EIP-2537	✅	V3.0.0
0x0d	BLS12_G2ADD	BLS12-381 G2 addition	EIP-2537	✅	V3.0.0
0x0e	BLS12_G2MSM	BLS12-381 G2 multi-scalar multiplication	EIP-2537	✅	V3.0.0
0x0f	BLS12_PAIRING_CHECK	BLS12-381 pairing check	EIP-2537	✅	V3.0.0
0x10	BLS12_MAP_FP_TO_G1	BLS12-381 map FP to G1	EIP-2537	✅	V3.0.0
0x11	BLS12_MAP_FP2_TO_G2	BLS12-381 map FP2 to G2	EIP-2537	✅	V3.0.0

Phantom transactions

A cross-space transaction is a transaction in the Conflux core space that, at some point during its execution, calls one of the state-changing (i.e., not view) methods of the CrossSpaceCall internal contract. Such transactions can change CFX balances and contract storage in both spaces, core and eSpace.

As EVM clients are not aware of Conflux space transactions (the two spaces use different transaction formats), we construct one or more phantom transactions (aka virtual transactions) for each call to the CrossSpaceCall internal contract. These phantom transactions are derived from the corresponding core space transaction, they do not exist in the ledger. Phantom transactions have the following special properties:

• gas and gasPrice are 0. Gas for cross-space transactions is charged in the core space. Therefore, the corresponding phantom transactions do not consume any gas.
• Invalid signature (r, s, v, standardV). The Conflux protocol is unable to sign transactions on behalf of the sender of the cross-space transaction. Therefore, phantom transactions use a fake signature that will not pass ECDSA verification.

Example

When we retrieve epoch 0x72819 in the Conflux core space, we see it contains a single Conflux transaction.

cfx_getBlockByEpochNumber(0x72819, true)

{
  "epochNumber": "0x72819",
  "hash": "0x7440c9e8ebb2e87a7d187e4ad6d09027d860b3948cf4364bb883c028b6c3a858",
  "transactions": [
    {
      "hash": "0xe89ef4b61434ec331b621b8687033f9e4058e76759a3522bdc50e0cb358f505e",
      "blockHash": "0x7440c9e8ebb2e87a7d187e4ad6d09027d860b3948cf4364bb883c028b6c3a858",
      "from": "NET8888:TYPE.USER:AAJFT5SK5RGK2KTJPMPUEJ69989N15KCCY7JAJEUP2",
      "to": "NET8888:TYPE.CONTRACT:ACAP3N9KXZ7C4TU5NUU8G65FJ7A09MG1FY77ZAYSVW",
      "gasPrice": "0x1",
      "gas": "0x8b28d",
      "storageLimit": "0x54",
      "r": "0x2b943e84111cd5f95fbdf15667329ac546c9e5b99548d3c3702aeced4f07de6d",
      "s": "0x2f47ae3c15ec2d1cbcf5bde3870aa21e1df54e8b7b926840a54faa9951cb3321",
      "v": "0x0",
      ...
    }
  ],
  ...
}

When we retrieve the corresponding block in the eSpace, we see it contains two phantom transactions.

eth_getBlockByNumber(0x72819, true)

{
  "hash": "0x7440c9e8ebb2e87a7d187e4ad6d09027d860b3948cf4364bb883c028b6c3a858",
  "number": "0x72819",
  "transactions": [
    {
      "hash": "0xfcdcf304b6b9dc263625b0924efaf3a7eb7044a17d27c0b8d631025b55d1147e",
      "blockHash": "0x7440c9e8ebb2e87a7d187e4ad6d09027d860b3948cf4364bb883c028b6c3a858",
      "from": "0x0000000000000000000000000000000000000000",
      "to": "0xf709629eee416c2d2a53692d38f1568538d8022f",
      "gasPrice": "0x0",
      "gas": "0x0",
      "r": "0x1",
      "s": "0x1",
      "v": "0x4593",
      ...
    },
    {
      "hash": "0xca2f5c5848458bea556f99e626db7108377d600e24add1920c4106358a1a5502",
      "blockHash": "0x7440c9e8ebb2e87a7d187e4ad6d09027d860b3948cf4364bb883c028b6c3a858",
      "from": "0xf709629eee416c2d2a53692d38f1568538d8022f",
      "to": "0xdacf3af269b55ece5fe3239626a27f2a76c48245",
      "gasPrice": "0x0",
      "gas": "0x0",
      "r": "0x1",
      "s": "0x1",
      "v": "0x4593",
      ...
    }
  ],
  ...
}

Resources

• EVM opcodes reference
• CIP-645: Align Conflux eSpace Behavior with EVM