package crypto import ( "crypto/sha256" "errors" "github.com/CityOfZion/neo-go/pkg/util" ) // MerkleTree implementation. type MerkleTree struct { root *MerkleTreeNode depth int } // NewMerkleTree returns new MerkleTree object. func NewMerkleTree(hashes []util.Uint256) (*MerkleTree, error) { if len(hashes) == 0 { return nil, errors.New("length of the hashes cannot be zero") } nodes := make([]*MerkleTreeNode, len(hashes)) for i := 0; i < len(hashes); i++ { nodes[i] = &MerkleTreeNode{ hash: hashes[i], } } root, err := buildMerkleTree(nodes) if err != nil { return nil, err } return &MerkleTree{ root: root, depth: 1, }, nil } // Root return the computed root hash of the MerkleTree. func (t *MerkleTree) Root() util.Uint256 { return t.root.hash } func buildMerkleTree(leaves []*MerkleTreeNode) (*MerkleTreeNode, error) { if len(leaves) == 0 { return nil, errors.New("length of the leaves cannot be zero") } if len(leaves) == 1 { return leaves[0], nil } parents := make([]*MerkleTreeNode, (len(leaves)+1)/2) for i := 0; i < len(parents); i++ { parents[i] = &MerkleTreeNode{} parents[i].leftChild = leaves[i*2] leaves[i*2].parent = parents[i] if i*2+1 == len(leaves) { parents[i].rightChild = parents[i].leftChild } else { parents[i].rightChild = leaves[i*2+1] leaves[i*2+1].parent = parents[i] } b1 := parents[i].leftChild.hash.Bytes() b2 := parents[i].rightChild.hash.Bytes() b1 = append(b1, b2...) parents[i].hash = hash256(b1) } return buildMerkleTree(parents) } // MerkleTreeNode represents a node in the MerkleTree. type MerkleTreeNode struct { hash util.Uint256 parent *MerkleTreeNode leftChild *MerkleTreeNode rightChild *MerkleTreeNode } // IsLeaf returns whether this node is a leaf node or not. func (n *MerkleTreeNode) IsLeaf() bool { return n.leftChild == nil && n.rightChild == nil } // IsRoot returns whether this node is a root node or not. func (n *MerkleTreeNode) IsRoot() bool { return n.parent == nil } func hash256(b []byte) util.Uint256 { var hash util.Uint256 hash = sha256.Sum256(b) hash = sha256.Sum256(hash.Bytes()) return hash }