merkletree

package module
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 Go to latest Published: Dec 15, 2022 License: AGPL-3.0 Imports: 12 Imported by: 0

README

go-merkletree-sql GoDoc Go Report Card Test

MerkleTree compatible with version from circomlib.

Adaptation of the merkletree from https://github.com/iden3/go-iden3-core/tree/v0.0.8 with several changes and more functionalities.

Usage

More detailed examples can be found at the tests, and in the documentation.

import (
	"fmt"
	"math/big"
	"testing"

	"github.com/iden3/go-iden3-core/db"
	"github.com/stretchr/testify/assert"
)

[...]

func TestExampleMerkleTree(t *testing.T) {
	mt, err := NewMerkleTree(db.NewMemoryStorage(), 10)
	assert.Nil(t, err)

	key := big.NewInt(1)
	value := big.NewInt(2)
	err = mt.Add(key, value)
	assert.Nil(t, err)
	fmt.Println(mt.Root().String())

	v, err := mt.Get(key)
	asseert.Equal(t, value, v)

	value = big.NewInt(3)
	err = mt.Update(key, value)

	proof, err := mt.GenerateProof(key, nil)
	assert.Nil(t, err)

	assert.True(t, VerifyProof(mt.Root(), proof, key, value))

	err := mt.Delete(big.NewInt(1)) // delete the leaf of key=1
	assert.Nil(t, err)
}

Documentation

Index

Constants

View Source 
const (
	// ElemBytesLen is the length of the Hash byte array
	ElemBytesLen = 32
)

Variables

View Source 
var (
	// ErrNodeKeyAlreadyExists is used when a node key already exists.
	ErrNodeKeyAlreadyExists = errors.New("key already exists")
	// ErrKeyNotFound is used when a key is not found in the MerkleTree.
	ErrKeyNotFound = errors.New("Key not found in the MerkleTree")
	// ErrNodeBytesBadSize is used when the data of a node has an incorrect
	// size and can't be parsed.
	ErrNodeBytesBadSize = errors.New("node data has incorrect size in the DB")
	// ErrReachedMaxLevel is used when a traversal of the MT reaches the
	// maximum level.
	ErrReachedMaxLevel = errors.New("reached maximum level of the merkle tree")
	// ErrInvalidNodeFound is used when an invalid node is found and can't
	// be parsed.
	ErrInvalidNodeFound = errors.New("found an invalid node in the DB")
	// ErrInvalidProofBytes is used when a serialized proof is invalid.
	ErrInvalidProofBytes = errors.New("the serialized proof is invalid")
	// ErrInvalidDBValue is used when a value in the key value DB is
	// invalid (for example, it doen't contain a byte header and a []byte
	// body of at least len=1.
	ErrInvalidDBValue = errors.New("the value in the DB is invalid")
	// ErrEntryIndexAlreadyExists is used when the entry index already
	// exists in the tree.
	ErrEntryIndexAlreadyExists = errors.New("the entry index already exists in the tree")
	// ErrNotWritable is used when the MerkleTree is not writable and a
	// write function is called
	ErrNotWritable = errors.New("Merkle Tree not writable")
)
View Source 
var ErrNotFound = errors.New("key not found")

ErrNotFound is used by the implementations of the interface db.Storage for when a key is not found in the storage

View Source 
var (
	// HashZero is used at Empty nodes
	HashZero = Hash{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
)

Functions

func Clone 

func Clone(b0 []byte) []byte

Clone clones a byte array into a new byte array

func Concat 

func Concat(vs ...[]byte) []byte

Concat concatenates arrays of bytes

func ElemBytesToBigInts 

func ElemBytesToBigInts(es []ElemBytes) []*big.Int

ElemBytesToBigInts serializes an array of ElemBytes to []byte.

func ElemBytesToBytes 

func ElemBytesToBytes(es []ElemBytes) []byte

ElemBytesToBytes serializes an array of ElemBytes to []byte.

func NewBigIntFromHashBytes 

func NewBigIntFromHashBytes(b []byte) (*big.Int, error)

NewBigIntFromHashBytes returns a *big.Int from a byte array, swapping the endianness in the process. This is the intended method to get a *big.Int from a byte array that previously has ben generated by the Hash.Bytes() method.

func SetBitBigEndian 

func SetBitBigEndian(bitmap []byte, n uint)

SetBitBigEndian sets the bit n in the bitmap to 1, in Big Endian.

func SwapEndianness 

func SwapEndianness(b []byte) []byte

SwapEndianness swaps the order of the bytes in the slice.

func TestBit 

func TestBit(bitmap []byte, n uint) bool

TestBit tests whether the bit n in bitmap is 1.

func TestBitBigEndian 

func TestBitBigEndian(bitmap []byte, n uint) bool

TestBitBigEndian tests whether the bit n in bitmap is 1, in Big Endian.

func VerifyProof 

func VerifyProof(rootKey *Hash, proof *Proof, k, v *big.Int) bool

VerifyProof verifies the Merkle Proof for the entry and root.

Types

type ElemBytes 

type ElemBytes [ElemBytesLen]byte

ElemBytes is the basic type used to store data in the MT. ElemBytes corresponds to the serialization of an element from mimc7.

func NewElemBytesFromBigInt 

func NewElemBytesFromBigInt(v *big.Int) (e ElemBytes)

func (*ElemBytes) BigInt 

func (e *ElemBytes) BigInt() *big.Int

func (*ElemBytes) String 

func (e *ElemBytes) String() string

String returns the first 4 bytes of ElemBytes in hex.

type Hash 

type Hash [32]byte

Hash is the generic type stored in the MerkleTree

func HashElems 

func HashElems(elems ...*big.Int) (*Hash, error)

HashElems performs a poseidon hash over the array of ElemBytes, currently we are using 2 elements. Uses poseidon.Hash to be compatible with the circom circuits implementations.

func HashElemsKey 

func HashElemsKey(key *big.Int, elems ...*big.Int) (*Hash, error)

HashElemsKey performs a poseidon hash over the array of ElemBytes, currently we are using 2 elements.

func LeafKey 

func LeafKey(k, v *Hash) (*Hash, error)

LeafKey computes the key of a leaf node given the hIndex and hValue of the entry of the leaf.

func NewHashFromBigInt 

func NewHashFromBigInt(b *big.Int) (*Hash, error)

NewHashFromBigInt returns a *Hash representation of the given *big.Int

func NewHashFromHex 

func NewHashFromHex(h string) (*Hash, error)

NewHashFromHex returns a *Hash representation of the given hex string

func NewHashFromString 

func NewHashFromString(s string, base int) (*Hash, error)

NewHashFromString returns a *Hash representation of the given decimal string

func RootFromProof 

func RootFromProof(proof *Proof, k, v *big.Int) (*Hash, error)

RootFromProof calculates the root that would correspond to a tree whose siblings are the ones in the proof with the leaf hashing to hIndex and hValue.

func (*Hash) BigInt 

func (h *Hash) BigInt() *big.Int

BigInt returns the *big.Int representation of the *Hash

func (*Hash) Equals 

func (h *Hash) Equals(h2 *Hash) bool

func (*Hash) Hex 

func (h *Hash) Hex() string

Hex returns the hexadecimal representation of the Hash

func (*Hash) MarshalText 

func (h *Hash) MarshalText() ([]byte, error)

MarshalText implements the marshaler for the Hash type

func (*Hash) String 

func (h *Hash) String() string

String returns string representation of the big.Int

func (*Hash) UnmarshalText 

func (h *Hash) UnmarshalText(b []byte) error

UnmarshalText implements the unmarshaler for the Hash type

type KV 

type KV struct {
	K []byte
	V Node
}

KV contains a key (K) and a value (V)

type KvMap 

type KvMap map[[sha256.Size]byte]KV

KvMap is a key-value map between a sha256 byte array hash, and a KV struct

func (KvMap) Get 

func (m KvMap) Get(k []byte) (Node, bool)

Get retrieves the value respective to a key from the KvMap

func (KvMap) Put 

func (m KvMap) Put(k []byte, v Node)

Put stores a key and a value in the KvMap

type MerkleTree 

type MerkleTree struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

MerkleTree is the struct with the main elements of the MerkleTree

func NewMerkleTree 

func NewMerkleTree(ctx context.Context, storage Storage,
	maxLevels int) (*MerkleTree, error)

NewMerkleTree loads a new MerkleTree. If in the storage already exists one will open that one, if not, will create a new one.

func (*MerkleTree) Add 

func (mt *MerkleTree) Add(ctx context.Context, k, v *big.Int) (*TransactionInfo, error)

Add new element to tree.

func (*MerkleTree) Delete 

func (mt *MerkleTree) Delete(ctx context.Context, k *big.Int) (*TransactionInfo, error)

Delete removes the specified Key from the MerkleTree and updates the path from the deleted key to the Root with the new values. This method removes the key from the MerkleTree, but does not remove the old nodes from the key-value database; this means that if the tree is accessed by an old Root where the key was not deleted yet, the key will still exist. If is desired to remove the key-values from the database that are not under the current Root, an option could be to dump all the leaves (using mt.DumpLeafs) and import them in a new MerkleTree in a new database (using mt.ImportDumpedLeafs), but this will loose all the Root history of the MerkleTree

func (*MerkleTree) GenerateProof 

func (mt *MerkleTree) GenerateProof(ctx context.Context, k *big.Int,
	rootKey *Hash) (p *Proof, value *big.Int, err error)

GenerateProof generates the proof of existence (or non-existence) of an Entry's hash Index for a Merkle Tree given the root. If the rootKey is nil, the current merkletree root is used

func (*MerkleTree) Get 

func (mt *MerkleTree) Get(ctx context.Context,
	k *big.Int) (key *big.Int, value *big.Int, siblings []*Hash, err error)

Get returns the value of the leaf for the given key

func (*MerkleTree) GetNode 

func (mt *MerkleTree) GetNode(ctx context.Context, key *Hash) (*Node, error)

GetNode gets a node by key from the MT. Empty nodes are not stored in the tree; they are all the same and assumed to always exist.

func (*MerkleTree) MaxLevels 

func (mt *MerkleTree) MaxLevels() int

MaxLevels returns the MT maximum level

func (*MerkleTree) Root 

func (mt *MerkleTree) Root() *Hash

Root returns the MerkleRoot

func (*MerkleTree) Snapshot 

func (mt *MerkleTree) Snapshot(
	ctx context.Context, rootKey *Hash) (*MerkleTree, error)

Snapshot returns a read-only copy of the MerkleTree

func (*MerkleTree) Update 

func (mt *MerkleTree) Update(ctx context.Context,
	k, v *big.Int) (*TransactionInfo, error)

Update updates the value of a specified key in the MerkleTree, and updates the path from the leaf to the Root with the new values. Returns the TransactionInfo.

func (*MerkleTree) Walk 

func (mt *MerkleTree) Walk(ctx context.Context, rootKey *Hash,
	f func(*Node)) error

Walk iterates over all the branches of a MerkleTree with the given rootKey if rootKey is nil, it will get the current RootKey of the current state of the MerkleTree. For each node, it calls the f function given in the parameters. See some examples of the Walk function usage in the merkletree.go and merkletree_test.go

type Node 

type Node struct {
	// Type is the type of node in the tree.
	Type NodeType
	// ChildL is the left child of a middle node.
	ChildL *Hash
	// ChildR is the right child of a middle node.
	ChildR *Hash
	// Entry is the data stored in a leaf node.
	Entry [2]*Hash
	// contains filtered or unexported fields
}

Node is the struct that represents a node in the MT. The node should not be modified after creation because the cached key won't be updated.

func NewNodeEmpty 

func NewNodeEmpty() *Node

NewNodeEmpty creates a new empty node.

func NewNodeFromBytes 

func NewNodeFromBytes(b []byte) (*Node, error)

NewNodeFromBytes creates a new node by parsing the input []byte.

func NewNodeLeaf 

func NewNodeLeaf(k, v *Hash) *Node

NewNodeLeaf creates a new leaf node.

func NewNodeMiddle 

func NewNodeMiddle(childL *Hash, childR *Hash) *Node

NewNodeMiddle creates a new middle node.

func (*Node) Key 

func (n *Node) Key() (*Hash, error)

Key computes the key of the node by hashing the content in a specific way for each type of node. This key is used as the hash of the merkle tree for each node.

func (*Node) String 

func (n *Node) String() string

String outputs a string representation of a node (different for each type).

func (*Node) Value 

func (n *Node) Value() []byte

Value returns the value of the node. This is the content that is stored in the backend database.

type NodeAux 

type NodeAux struct {
	Key   *Hash `json:"key"`
	Value *Hash `json:"value"`
}

NodeAux contains the auxiliary node used in a non-existence proof.

type NodeType 

type NodeType byte

NodeType defines the type of node in the MT. 

const (
	// NodeTypeMiddle indicates the type of middle Node that has children.
	NodeTypeMiddle NodeType = 0
	// NodeTypeLeaf indicates the type of leaf Node that contains a key &
	// value.
	NodeTypeLeaf NodeType = 1
	// NodeTypeEmpty indicates the type of empty Node.
	// Virtual node that is not stored in the database.
	// Also, this node haven't representation on tree.
	NodeTypeEmpty NodeType = 2
)

type Proof 

type Proof struct {
	// Existence indicates whether this is a proof of existence or
	// non-existence
	Existence bool

	// Auxiliary node if needed. The filed can return when p.Existence = false.
	// Represent node that exists on position instead expected key.
	// On case when on expected position exists EmptyNode, NodeAux will nil.
	NodeAux *NodeAux
	// contains filtered or unexported fields
}

Proof defines the required elements for a MT proof of existence or non-existence.

func NewProofFromData 

func NewProofFromData(existence bool,
	allSiblings []*Hash,
	nodeAux *NodeAux) (*Proof, error)

NewProofFromData reconstructs proof from siblings and auxiliary node

func (*Proof) Bytes 

func (p *Proof) Bytes() []byte

Bytes serializes a Proof into a byte array.

func (*Proof) MarshalJSON 

func (p *Proof) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface

func (*Proof) Siblings 

func (p *Proof) Siblings() []*Hash

Siblings returns proof's siblings.

func (*Proof) UnmarshalJSON 

func (p *Proof) UnmarshalJSON(data []byte) error

UnmarshalJSON implements json.Unmarshaler interface

type Storage 

type Storage interface {
	Get(context.Context, []byte) (*Node, error)
	Put(ctx context.Context, k []byte, v *Node) error
	GetRoot(context.Context) (*Hash, error)
	SetRoot(context.Context, *Hash) error
}

Storage is the interface that defines the methods for the storage used in the merkletree. Examples of the interface implementation can be found at db/memory and db/leveldb directories.

type TransactionInfo 

type TransactionInfo struct {
	OldRoot   *Hash
	NewRoot   *Hash
	Siblings  []*Hash
	OldKey    *Hash
	OldValue  *Hash
	NewKey    *Hash
	NewValue  *Hash
	IsOldKey0 bool
	Fnc       TreeOperation
}

TransactionInfo defines information about change merkletree.

type TreeOperation 

type TreeOperation int
const (
	NOP TreeOperation = iota
	Update
	Insert
	Delete
)

Source Files

View all Source files

Directories

Path Synopsis
db
memory
test

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