github.com/klaytn/klaytn@v1.10.2/blockchain/types/derivesha/simple.go (about)

     1  // Modifications Copyright 2018 The klaytn Authors
     2  // Copyright 2015 The go-ethereum Authors
     3  // This file is part of the go-ethereum library.
     4  //
     5  // The go-ethereum library is free software: you can redistribute it and/or modify
     6  // it under the terms of the GNU Lesser General Public License as published by
     7  // the Free Software Foundation, either version 3 of the License, or
     8  // (at your option) any later version.
     9  //
    10  // The go-ethereum library is distributed in the hope that it will be useful,
    11  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    13  // GNU Lesser General Public License for more details.
    14  //
    15  // You should have received a copy of the GNU Lesser General Public License
    16  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    17  //
    18  // This file is derived from core/types/derive_sha.go (2018/06/04).
    19  // Modified and improved for the klaytn development.
    20  
    21  package derivesha
    22  
    23  import (
    24  	"github.com/klaytn/klaytn/blockchain/types"
    25  	"github.com/klaytn/klaytn/common"
    26  	"github.com/klaytn/klaytn/crypto/sha3"
    27  )
    28  
    29  // An alternative implementation of DeriveSha()
    30  // This function generates a hash of `DerivableList` by simulating merkle tree generation
    31  type DeriveShaSimple struct{}
    32  
    33  func (d DeriveShaSimple) DeriveSha(list types.DerivableList) common.Hash {
    34  	hasher := sha3.NewKeccak256()
    35  
    36  	encoded := make([][]byte, 0, list.Len())
    37  	for i := 0; i < list.Len(); i++ {
    38  		hasher.Reset()
    39  		hasher.Write(list.GetRlp((i)))
    40  		encoded = append(encoded, hasher.Sum(nil))
    41  	}
    42  
    43  	for len(encoded) > 1 {
    44  		// make even numbers
    45  		if len(encoded)%2 == 1 {
    46  			encoded = append(encoded, encoded[len(encoded)-1])
    47  		}
    48  
    49  		for i := 0; i < len(encoded)/2; i++ {
    50  			hasher.Reset()
    51  			hasher.Write(encoded[2*i])
    52  			hasher.Write(encoded[2*i+1])
    53  
    54  			encoded[i] = hasher.Sum(nil)
    55  		}
    56  
    57  		encoded = encoded[0 : len(encoded)/2]
    58  	}
    59  
    60  	if len(encoded) == 0 {
    61  		hasher.Reset()
    62  		hasher.Write(nil)
    63  		return common.BytesToHash(hasher.Sum(nil))
    64  	}
    65  
    66  	return common.BytesToHash(encoded[0])
    67  }