I wanna compute sha256 in Solidity Assembly for hash of getting bytes slice.


Sha256 is one of a few precompiled smart contracts:

function subSha256(bytes memory data, uint256 offset, uint256 length) public view returns(bytes32) {
    bytes32[1] memory result;
    assembly {
        pop(staticcall(gas, 0x02, add(add(data, 32), offset), length, result, 32))
    return result[0];
  • I'm pretty sure that in solc 0.5.x onward, you can simply use staticcall at the Solidity level, and get (bool success, bytes memory result) returned to you. May 26 '20 at 16:54
  • @goodvibration core feature of this code is getting hash for a slice of an array without copying it into separate bytes array.
    – k06a
    May 26 '20 at 17:48

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