c08dc59aad
* beacon/types: add beacon chain data types * beacon/merkle: added comments * go.mod: cleanups --------- Co-authored-by: Péter Szilágyi <peterke@gmail.com>
68 lines
2.1 KiB
Go
68 lines
2.1 KiB
Go
// Copyright 2022 The go-ethereum Authors
|
|
// This file is part of the go-ethereum library.
|
|
//
|
|
// The go-ethereum library is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// The go-ethereum library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU Lesser General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Lesser General Public License
|
|
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
// Package merkle implements proof verifications in binary merkle trees.
|
|
package merkle
|
|
|
|
import (
|
|
"crypto/sha256"
|
|
"errors"
|
|
"reflect"
|
|
|
|
"github.com/ethereum/go-ethereum/common"
|
|
"github.com/ethereum/go-ethereum/common/hexutil"
|
|
)
|
|
|
|
// Value represents either a 32 byte leaf value or hash node in a binary merkle tree/partial proof.
|
|
type Value [32]byte
|
|
|
|
// Values represent a series of merkle tree leaves/nodes.
|
|
type Values []Value
|
|
|
|
var valueT = reflect.TypeOf(Value{})
|
|
|
|
// UnmarshalJSON parses a merkle value in hex syntax.
|
|
func (m *Value) UnmarshalJSON(input []byte) error {
|
|
return hexutil.UnmarshalFixedJSON(valueT, input, m[:])
|
|
}
|
|
|
|
// VerifyProof verifies a Merkle proof branch for a single value in a
|
|
// binary Merkle tree (index is a generalized tree index).
|
|
func VerifyProof(root common.Hash, index uint64, branch Values, value Value) error {
|
|
hasher := sha256.New()
|
|
for _, sibling := range branch {
|
|
hasher.Reset()
|
|
if index&1 == 0 {
|
|
hasher.Write(value[:])
|
|
hasher.Write(sibling[:])
|
|
} else {
|
|
hasher.Write(sibling[:])
|
|
hasher.Write(value[:])
|
|
}
|
|
hasher.Sum(value[:0])
|
|
if index >>= 1; index == 0 {
|
|
return errors.New("branch has extra items")
|
|
}
|
|
}
|
|
if index != 1 {
|
|
return errors.New("branch is missing items")
|
|
}
|
|
if common.Hash(value) != root {
|
|
return errors.New("root mismatch")
|
|
}
|
|
return nil
|
|
}
|