Precompiled Contracts
Kaia provides several useful precompiled contracts, none of which are state-changing. These contracts are implemented in the platform itself as a native implementation, which means they are part of the Kaia client specifications. The precompiled contracts from address 0x01 through 0x0A are the same as those in Ethereum. The utility of precompiles falls into four major categories: . Elliptic curve digital signature recovery. . Hash Methods . Memory copying . Methods to enable elliptic curve maths for zk proofs. Kaia additionally implements precompiled contracts from 0x3FD through 0x3FF to support new Kaia features.
Contracts deployed before the istanbul EVM hardfork should use the original addresses.
- case 1) The contracts deployed in Kairos at block number
#75373310recognizes 0x09, 0x0a, and 0x0b as addresses of vmLog, feePayer, and validateSender, respectively, and blake2f cannot be used. - case 2) The contracts deployed in Kairos at block number
#75373314recognizes 0x09 as the address of blake2f, and recognizes 0x3fd, 0x3fe, and 0xff as addresses of vmLog, feePayer, and validateSender.
Precompiled contracts related hardfork changes can be found at the bottom of this page. Go to Hardfork Changes.
Address 0x01: ecrecover(hash, v, r, s)
The address 0x01 implements ecrecover. It returns the address from the given signature by calculating a recovery function of ECDSA. It is the only precompile that comes with a solidity wrapper. Its function prototype is as follows:
hàm ecRecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) chế độ xem công khai trả về (địa chỉ) { địa chỉ r = ecrecover(băm, v, r, s); // hàm nguyên mẫu yêu cầu(r != address(0), "chữ ký không hợp lệ");} // trình bao bọc solidity
Address 0x02: sha256(data)
The address 0x02 implements SHA256 hash. It returns a SHA256 hash from the given data. It is mostly used by Bitcoin and Zcash as Ethereum uses Keccak256. Its function prototype is as follows:
function sha256(uint256 numberToHash) public view returns (bytes32 hash) { (bool ok, bytes memory hashData) = address(0x02).staticcall(abi.encode(numberToHash)); require(ok); hash = abi.decode(hashData, (bytes32));}
usage in Yul / Inline Assembly:
function sha256Yul(uint256 numberToHash) public view returns (bytes32) { assembly { mstore(0, numberToHash) // store number in the zeroth memory word let ok := staticcall(gas(), 2, 0, 32, 0, 32) if iszero(ok) { revert(0,0) } return(0, 32) }}
Address 0x03: ripemd160(data)
The address 0x03 implements RIPEMD160 hash. It returns a RIPEMD160 hash from the given data. Its function prototype is as follows:
function RIPEMD160(bytes calldata data) public view returns (bytes20 h) { (bool ok, bytes memory out) = address(0x03).staticcall(data); require(ok); h = bytes20(abi.decode(out, (bytes32)) << 96);}
Address 0x04: datacopy(data)
The address 0x04 implements datacopy (i.e., identity function). It returns the input data directly without any modification. This precompiled contract is not supported by the Solidity compiler. The following code with inline assembly can be used to call this precompiled contract.
hàm callDatacopy(byte bộ nhớ dữ liệu) trả về công khai (byte bộ nhớ) { byte bộ nhớ ret = byte mới (dữ liệu.chiều dài); lắp ráp { cho len := mload(dữ liệu) nếu iszero(gọi(gas, 0x04, 0, thêm(dữ liệu, 0x20), len, thêm(ret, 0x20), len)) { không hợp lệ() } } trả về ret;}
Address 0x05: bigModExp(base, exp, mod)
The address 0x05 implements the formula base**exp % mod. It returns the result from the given data. This precompiled contract is not supported by the Solidity compiler. The following code can be used to call this precompiled contract. Note that although this precompiled contract supports an arbitrary length of inputs, the below code uses a fixed length of inputs as an example.
function callBigModExp(bytes32 base, bytes32 exponent, bytes32 modulus) public returns (bytes32 result) { assembly { // free memory pointer let memPtr := mload(0x40) // length of base, exponent, modulus mstore(memPtr, 0x20) mstore(add(memPtr, 0x20), 0x20) mstore(add(memPtr, 0x40), 0x20) // assign base, exponent, modulus mstore(add(memPtr, 0x60), base) mstore(add(memPtr, 0x80), exponent) mstore(add(memPtr, 0xa0), modulus) // call the precompiled contract BigModExp (0x05) let success := call(gas, 0x05, 0x0, memPtr, 0xc0, memPtr, 0x20) switch success case 0 { revert(0x0, 0x0) } default { result := mload(memPtr) } }}
Address 0x06: bn256Add(ax, ay, bx, by)
The address 0x06 implements a native elliptic curve point addition. It returns an elliptic curve point representing (ax, ay) + (bx, by) such that (ax, ay) and (bx, by) are valid points on the curve bn256. This precompiled contract is not supported by the Solidity compiler. The following code can be used to call this precompiled contract.
function callBn256Add(bytes32 ax, bytes32 ay, bytes32 bx, bytes32 by) public returns (bytes32[2] memory result) { bytes32[4] memory input; input[0] = ax; input[1] = ay; input[2] = bx; input[3] = by; assembly { let success := call(gas, 0x06, 0, input, 0x80, result, 0x40) switch success case 0 { revert(0,0) } }}
Address 0x07: bn256ScalarMul(x, y, scalar)
The address 0x07 implements a native elliptic curve multiplication with a scalar value. It returns an elliptic curve point representing scalar * (x, y) such that (x, y) is a valid curve point on the curve bn256. This precompiled contract is not supported by the Solidity compiler. The following code can be used to call this precompiled contract.
function callBn256ScalarMul(bytes32 x, bytes32 y, bytes32 scalar) public returns (bytes32[2] memory result) { bytes32[3] memory input; input[0] = x; input[1] = y; input[2] = scalar; assembly { let success := call(gas, 0x07, 0, input, 0x60, result, 0x40) switch success case 0 { revert(0,0) } }}
Address 0x08: bn256Pairing(a1, b1, a2, b2, a3, b3, ..., ak, bk)
The address 0x08 implements elliptic curve paring operation to perform zkSNARK verification. For more information, see EIP-197. This precompiled contract is not supported by the Solidity compiler. The following code can be used to call this precompiled contract.
function callBn256Pairing(bytes memory input) public returns (bytes32 result) { // input is a serialized bytes stream of (a1, b1, a2, b2, ..., ak, bk) from (G_1 x G_2)^k uint256 len = input.length; require(len % 192 == 0); assembly { let memPtr := mload(0x40) let success := call(gas, 0x08, 0, add(input, 0x20), len, memPtr, 0x20) switch success case 0 { revert(0,0) } default { result := mload(memPtr) } }}
Address 0x09: blake2F(rounds, h, m, t, f)
The address 0x09 implements BLAKE2b F compression function. For more information, see EIP-152. This precompiled contract is not supported by the Solidity compiler. The following code can be used to call this precompiled contract.
function callBlake2F(uint32 rounds, bytes32[2] memory h, bytes32[4] memory m, bytes8[2] memory t, bool f) public view returns (bytes32[2] memory) { bytes32[2] memory output; bytes memory args = abi.encodePacked(rounds, h[0], h[1], m[0], m[1], m[2], m[3], t[0], t[1], f); assembly { if iszero(staticcall(not(0), 0x09, add(args, 32), 0xd5, output, 0x40)) { revert(0, 0) } } return output;}
Address 0x0A: kzg(data)
The address 0x0A implements the KZG proof verification to a given value at a given point. For more information, see EIP-4844. This precompiled contract is not supported by the Solidity compiler. The following code can be used to call this precompiled contract.
function callKzg(bytes memory data) public returns (bytes memory) { bytes memory ret; assembly { let len := mload(data) if iszero(call(gas(), 0x0a, 0, add(data, 0x20), len, 0, 0)) { revert (0,0) } } return ret;}
Địa chỉ 0x0B: bls12381G1Add(input)
Địa chỉ 0x0B thực hiện thao tác bổ sung BLS12381 G1. Để biết thêm thông tin, hãy xem EIP-2537. This precompiled contract is not supported by the Solidity compiler. The following code can be used to call this precompiled contract.
hàm bls12381add() công khai trả về (byte bộ nhớ) { byte bộ nhớ đầu vào = hex"000000000000000000000000000000000012196c5a43d69224d8713389285f26b98f86ee910ab3dd668e413738282003cc5b7357af9a7af54bb713d62255e80 f560000000000000000000000000000000000006ba8102bfbeea4416b710c73e8cce3032c31c6269c44906f8ac4f7874ce99fb17559992486528963884ce429a992fe e00000000000000000000000000000000000001101098f5c39893765766af4512a0c74e1bb89bc7e6fdf14e3e7337d257cc0f94658179d83320b99f31ff94cd2bac00000000000000000000000000000000000003e1a9f9f44ca2cdab4f43a1a3ee3470fdf90b2fc228eb3b709fcd72f014838ac82a6d797aeefed9a0804b22ed1ce8f7"; (bool ok, đầu ra bộ nhớ byte) = địa chỉ(0x0b).gọi(đầu vào); yêu cầu(ok, "bls12381 G1 thêm thao tác không thành công"); trả về đầu ra;}
Địa chỉ 0x0C: bls12381G1MultiExp(input)
Địa chỉ 0x0C thực hiện phép nhân G1 của BLS12381. Để biết thêm thông tin, hãy xem EIP-2537. This precompiled contract is not supported by the Solidity compiler. The following code can be used to call this precompiled contract.
hàm bls12381mul() công khai trả về (byte bộ nhớ) { byte bộ nhớ đầu vào = hex"0000000000000000000000000000000000112b98340eee2777cc3c14163dea3ec97977ac3dc5c70da32e6e87578f44912e902ccef9efe28d4a78b8999dfbca9426000000000000000000000000000000000000 0186b28d92356c4dfec4b5201ad099dbdede3781f8998ddf929b4cd7756192185ca7b8f4ef7088f813270ac3d48868a2100000000000000000000000000000000000000000000000000000000000000000002"; (bool ok, đầu ra bộ nhớ byte) = địa chỉ(0x0c).gọi(đầu vào); yêu cầu(ok, "bls12381 G1 đa hoạt động không thành công"); trả về đầu ra;}hàm bls12381multiexp() trả về công khai (byte bộ nhớ) { byte bộ nhớ đầu vào = hex""; (bool ok, byte bộ nhớ đầu ra) = địa chỉ(0x0c).call(đầu vào); yêu cầu(ok, "bls12381 G1 multiexp hoạt động không thành công"); trả về đầu ra;}
Địa chỉ 0x0D: bls12381G2Add(input)
Địa chỉ 0x0D thực hiện thao tác cộng BLS12381 G2. Để biết thêm thông tin, hãy xem EIP-2537. Hợp đồng được biên dịch trước này không được trình biên dịch Solidity hỗ trợ. Có thể sử dụng đoạn mã sau để gọi hợp đồng được biên dịch trước này.
hàm bls12381g2add() trả về công khai (byte bộ nhớ) { byte bộ nhớ đầu vào = hex""; (bool ok, byte bộ nhớ đầu ra) = địa chỉ(0x0d).call(đầu vào); yêu cầu(ok, "bls12381 G2 thêm thao tác không thành công"); trả về đầu ra;}
Địa chỉ 0x0E: bls12381G2MultiExp(input)
Địa chỉ 0x0E thực hiện phép nhân BLS12381 G2. Để biết thêm thông tin, hãy xem EIP-2537. Hợp đồng được biên dịch trước này không được trình biên dịch Solidity hỗ trợ. Có thể sử dụng đoạn mã sau để gọi hợp đồng được biên dịch trước này.
hàm bls12381g2mul() public returns (bytes memory) { bytes memory input = hex"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"; (bool ok, bytes memory output) = address(0x0e).call(input); require(ok, "bls12381 G2 mul operation failed"); return output;}function bls12381g2multiexp() public returns (bytes memory) { bytes memory input = 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(bool ok, bytes memory output) = address(0x0e).call(input); require(ok, "bls12381 G2 multiexp operation failed"); return output;}
Địa chỉ 0x0F: bls12381 Ghép nối(đầu vào)
Địa chỉ 0x0F thực hiện hoạt động ghép nối BLS12381. Để biết thêm thông tin, hãy xem EIP-2537. Hợp đồng được biên dịch trước này không được trình biên dịch Solidity hỗ trợ. Có thể sử dụng đoạn mã sau để gọi hợp đồng được biên dịch trước này.
hàm bls12381pairing() trả về công khai (byte bộ nhớ) { byte bộ nhớ đầu vào = hex""; (bool ok, byte bộ nhớ đầu ra) = địa chỉ(0x0f).call(đầu vào); yêu cầu(ok, "hoạt động ghép nối bls12381 không thành công"); trả về đầu ra;}
Địa chỉ 0x10: bls12381MapG1(input)
Địa chỉ 0x10 thực hiện hoạt động Bản đồ G1 của BLS12381. Để biết thêm thông tin, hãy xem EIP-2537. Hợp đồng được biên dịch trước này không được trình biên dịch Solidity hỗ trợ. Có thể sử dụng đoạn mã sau để gọi hợp đồng được biên dịch trước này.
hàm bls12381mapg1() trả về công khai (byte bộ nhớ) { byte bộ nhớ đầu vào = hex"0000000000000000000000000000000001443e61dbf14b6c6ed99e1917ecfbe5a4a23ab9bdd3bb089fbba76d795d715d9d2e3c7d8db0b7a9434ad691b68bad3b2"; (bool ok, byte bộ nhớ đầu ra) = address(0x10).call(đầu vào); require(ok, "bls12381 G1 map operation failed"); trả về đầu ra;}
Địa chỉ 0x11: bls12381MapG2(input)
Địa chỉ 0x11 thực hiện hoạt động BLS12381 Map G2. Để biết thêm thông tin, hãy xem EIP-2537. Hợp đồng được biên dịch trước này không được trình biên dịch Solidity hỗ trợ. Có thể sử dụng đoạn mã sau để gọi hợp đồng được biên dịch trước này.
hàm bls12381mapg2() công khai trả về (byte bộ nhớ) { byte bộ nhớ đầu vào = lục giác"0000000000000000000000000000000010e53fe9fa94ca622cfa370129c1619b2426bd9d50f4b5eb8a3f681479128dbe92adde15477ad8a4463b08f1a02a62d500000000000000000000000000000000000014d10a90709789b25369f0376f39b16860aee1ddc3a4340542abff0077a4af8da946cc29fb6afd9930b872ea98749be5"; (bool ok, đầu ra bộ nhớ byte) = địa chỉ (0x11). gọi (đầu vào); yêu cầu (ok, "bls12381 thao tác ánh xạ G2 không thành công"); trả về đầu ra;}
Address 0x3fd: vmLog(str)
The address 0x3FD prints the specified string str to a specific file or passes it to the logger module. For more information, see debug_setVMLogTarget. Note that this precompiled contract should be used only for debugging purposes, and it is required to enable the --vmlog option when the Kaia node starts. Also, the log level of the Kaia node should be 4 or more to see the output of vmLog. Hợp đồng được biên dịch trước này không được trình biên dịch Solidity hỗ trợ. Có thể sử dụng đoạn mã sau để gọi hợp đồng được biên dịch trước này.
function callVmLog(bytes memory str) public { address(0x3fd).call(str);}
Address 0x3fe: feePayer()
The address 0x3FE returns a fee payer of the executing transaction. Hợp đồng được biên dịch trước này không được trình biên dịch Solidity hỗ trợ. Có thể sử dụng đoạn mã sau để gọi hợp đồng được biên dịch trước này.
function feePayer() internal returns (address addr) { assembly { let freemem := mload(0x40) let start_addr := add(freemem, 12) if iszero(call(gas, 0x3fe, 0, 0, 0, start_addr, 20)) { invalid() } addr := mload(freemem) }}
Address 0x3ff: validateSender()
The address 0x3FF validates the sender's signature with the message. Since Kaia decouples key pairs from addresses, it is required to validate that a signature is properly signed by the corresponding sender. To do that, this precompiled contract receives three parameters:
- The sender's address to get the public keys
- The message hash that is used to generate the signature
- The signatures that are signed by the sender's private keys with the given message hash
The precompiled contract validates that the given signature is properly signed by the sender's private keys. Note that Kaia natively support multi signatures, which means there can be multiple signatures. The signature must be 65 bytes long.
function ValidateSender(address sender, bytes32 msgHash, bytes sigs) public returns (bool) { require(sigs.length % 65 == 0); bytes memory data = new bytes(20+32+sigs.length); uint idx = 0; uint i; for( i = 0; i < 20; i++) { data[idx++] = (bytes20)(sender)[i]; } for( i = 0; i < 32; i++ ) { data[idx++] = msgHash[i]; } for( i = 0; i < sigs.length; i++) { data[idx++] = sigs[i]; } assembly { // skip length header. let ptr := add(data, 0x20) if iszero(call(gas, 0x3ff, 0, ptr, idx, 31, 1)) { invalid() } return(0, 32) }}
Hardfork Changes
| Hardfork | New items | Changes |
|---|---|---|
| Cancun EVM | kzg (0x0a) precompiled contract | |
| Kore | modExp (0x05) precompiled contract use new gas calculation logic. Computation cost also affected. Become more accurate. | |
| Istanbul EVM | blake2f (0x09) precompiled contract | kaia precompiled contract addresses has been moved from 0x09,0x0A,0x0B to 0x3FD,0x3FE,0x3FF. see the below precompiled contract address change table for detail. |
Precompiled contract address change
| Precompiled Contract | address BEFORE istanbul EVM hardfork | address AFTER istanbul EVM hardfork |
|---|---|---|
| vmLog | 0x09 | 0x3fd |
| feePayer | 0x0a | 0x3fe |
| validateSender | 0x0b | 0x3ff |