swarm/storage: binary merle tree with proof of inclusion

swarm/storage/binarymerkle.go

@@ -0,0 +1,578 @@
+package storage
+
+// provides a binary merkle tree implementation.
+
+import (
+	"bytes"
+	_ "crypto/sha256"
+	"errors"
+	"fmt"
+	"hash"
+	"io"
+
+	"github.com/ethereum/go-ethereum/crypto/sha3"
+)
+
+var hashFunc Hasher = sha3.NewKeccak256 //default hasher
+
+const (
+	segmentsize int = 32
+)
+
+type state struct {
+	btree BTree
+	root  Root
+}
+
+// A merkle tree for a user that stores the entire tree
+// Specifically this tree is left a leaning balanced binary tree
+// Where each node holds the hash of its leaves
+// And the rootHash is the root node hashed with the count
+// This tree is immutable
+type BTree struct {
+	count    uint64
+	root     *node
+	rootHash []byte
+	chunklen int
+	//hashFunc Hasher
+}
+
+type node struct {
+	label    []byte
+	children [2]*node // if all nil, leaf node
+
+	// Representation invariants:
+	// if children[0] is nil, children[1] is nil
+	// if both children non nil:
+	//      label is hash of (children[0].label + children[1].label)
+	// if leaf: label is arbitrary data
+	// else if children[1] is nil, label=hash(children[0].label)
+}
+
+type jobparam struct {
+	//data [][]byte
+	n0 *node
+	n1 *node
+	id int
+}
+
+type jobresult struct {
+	n  *node
+	id int
+}
+
+func (t BTree) Count() uint64 {
+	return t.count
+}
+
+// The hash/root of an empty BTree does not matter
+func (t BTree) Root() []byte {
+	return t.rootHash
+}
+
+// All trees should pass , unless they are invalid, which should only happen
+// if incorrectly built or modified.
+// Checks the rep invariants
+func (t BTree) Validate() error {
+	count, height, err := t.root.validate()
+	if err != nil {
+		return err
+	}
+	if count != t.count {
+		return fmt.Errorf("Incorrect count. Was %d, should be %d", t.count, count)
+	}
+	if height != GetHeight(count) {
+		return fmt.Errorf("Incorrect height. Was %d, should be %d", height, GetHeight(count))
+	}
+
+	rootLabel := make([]byte, 0)
+	if height > 0 {
+		rootLabel = t.root.label
+	}
+	h := rootHash(count, rootLabel)
+	if !bytes.Equal(t.rootHash, h) {
+		return fmt.Errorf("Incorrect rootHash")
+	}
+	return nil
+}
+
+// Checks the rep invariants
+func (t *node) validate() (count uint64, height int, err error) {
+	if t == nil {
+		return 0, 0, nil
+	}
+	if t.children[0] == nil {
+		if t.children[1] != nil {
+			return 0, 0, fmt.Errorf("Invalid Node: Node missing first child, but has second")
+		}
+		// Leaf node
+		return 1, 1, nil
+	}
+
+	// Not a leaf node
+	count, height, err = t.children[0].validate()
+	if err != nil {
+		return
+	}
+	if t.children[1] != nil {
+		count2, height2, err2 := t.children[1].validate()
+		count += count2
+		if err2 != nil {
+			return count, height, err2
+		}
+		if height2 != height {
+			return count, height, fmt.Errorf("Invalid Node: height mismatch between children")
+		}
+	}
+	h := makeHash(t.children[0], t.children[1])
+	if !bytes.Equal(h, t.label) {
+		return 0, 0, fmt.Errorf("Invalid Node: Node hash mismatch")
+	}
+
+	height++
+	return
+}
+
+func rootHash(count uint64, data []byte) []byte {
+	h := hashFunc()
+	h.Reset()
+	h.Write(data)
+	//binary.Write(h, binary.LittleEndian, count)
+	return h.Sum(nil)
+}
+
+func makeHash(left, right *node) []byte {
+	h := hashFunc()
+	h.Reset()
+
+	if left != nil {
+		h.Write(left.label)
+		if right != nil {
+			h.Write(right.label)
+		}
+	}
+	return h.Sum(nil)
+}
+
+// Returns the height of the tree containing count leaf nodes.
+// This the number of nodes (including the final leaf) from the root to
+// any leaf.
+func GetHeight(count uint64) int {
+	if count == 0 {
+		return 0
+	}
+	height := 0
+	for count > (1 << uint(height)) {
+		height++
+	}
+	return height + 1
+}
+
+// Build Binary Merkle Tree over data segments of segmentsize len with a specific hash func
+// Return
+// BMT - The BMT Representation of the data
+// ROOT - BMT Root
+// Count - Numers of leafs at the BMT
+// err
+// The bmt computation is done in parallel by deviding the tree to  subtree .
+// (each sub tree is calculated in parallel using goroutine ) and then merge the results in parallel and get the tree.
+// The paralel merging is done by creating seperate channel for each node and make it to wait(on a seperate go routine) for the calculation of
+// its left and right childerens.
+func BuildBMT(h Hasher, data []byte, validate bool) (bmt *BTree, roor *Root, count int, err error) {
+
+	if (len(data) & (len(data) - 1)) == 0 { //check if power of 2
+		return buildBMTfaster(h, data, validate)
+	} else {
+		return buildBMTfast(h, data, validate)
+	}
+}
+
+//This function assume its data len value is a power of 2
+func buildBMTfaster(h Hasher, data []byte, validate bool) (bmt *BTree, roor *Root, count int, err error) {
+
+	datalen := len(data)
+	if datalen == 0 {
+		return nil, nil, 0, errors.New("data length is 0 ")
+	}
+	hashFunc = h
+	leafcount := datalen / segmentsize
+	if datalen%segmentsize != 0 {
+		leafcount++
+	}
+	var rootnode *node
+	var subtreescount = 4
+	//setting the subtreescount to 4 yield the best benchmarks results.
+	if leafcount < 4 {
+		subtreescount = 2
+	}
+
+	if leafcount > 1 {
+		subtreesize := datalen / subtreescount
+		subtreeleafcount := subtreesize / segmentsize
+		if subtreesize%segmentsize != 0 {
+			subtreeleafcount++
+		}
+		subtreeheight := GetHeight(uint64(subtreeleafcount))
+		height := GetHeight(uint64(subtreescount))
+		results := make([]chan *node, (1 << uint(height))) //array of channels for each node
+		//start := time.Now()
+
+		for i := 0; i < subtreescount; i++ {
+			results[i] = make(chan *node)
+			results[subtreescount+i] = make(chan *node)
+			go func(subdata []byte, index int) {
+				subtreerootnode, _ := buildNode(subdata, subtreeheight)
+				results[index] <- subtreerootnode
+			}(data[i*subtreesize:(i+1)*subtreesize], i)
+		}
+		for i := 0; i < subtreescount-1; i++ {
+			go func(index int, resultindex int) {
+				var leftnode, rightnode *node
+				select {
+				case leftnode = <-results[index]:
+					rightnode = <-results[index+1]
+				case rightnode = <-results[index+1]:
+					leftnode = <-results[index]
+				}
+				results[resultindex] <- &node{label: makeHash(leftnode, rightnode),
+					children: [2]*node{leftnode, rightnode}}
+			}(i*2, subtreescount+i)
+		}
+
+		rootnode = <-results[(1<<uint(height)-1)-1]
+	} else {
+		rootnode = &node{label: data, children: [2]*node{nil, nil}}
+	}
+
+	tree := &BTree{uint64(leafcount), rootnode, rootHash(uint64(leafcount), rootnode.label), datalen}
+
+	if validate {
+		err = tree.Validate()
+		if err != nil {
+			return nil, nil, 0, errors.New("Validation error")
+		}
+		if tree.Count() != uint64(leafcount) {
+			return nil, nil, 0, errors.New("Validation count error")
+		}
+	}
+	return tree, &Root{uint64(leafcount), tree.Root()}, leafcount, nil
+
+}
+func buildBMTfast(h Hasher, data []byte, validate bool) (bmt *BTree, roor *Root, count int, err error) {
+
+	datalen := len(data)
+	if datalen == 0 {
+		return nil, nil, 0, errors.New("data length is 0 ")
+	}
+	hashFunc = h
+	blocks := splitData(data, segmentsize)
+	leafcount := len(blocks)
+	var rootnode *node
+	var subtreescount = 4
+	//setting the subtreescount to 4 yield the best benchmarks results.
+	if leafcount < 4 {
+		subtreescount = 2
+	}
+	if leafcount > 1 {
+		subtreesize := leafcount / subtreescount
+		subtreeheight := GetHeight(uint64(subtreesize))
+		height := GetHeight(uint64(subtreescount))
+		results := make([]chan *node, (1 << uint(height))) //array of channels for each node
+
+		for i := 0; i < subtreescount; i++ {
+			results[i] = make(chan *node)
+			results[subtreescount+i] = make(chan *node)
+			go func(subdata [][]byte, index int) {
+				subtreerootnode, _ := buildNode2(subdata, subtreeheight)
+				results[index] <- subtreerootnode
+			}(blocks[i*(leafcount/subtreescount):(i+1)*(leafcount/subtreescount)], i)
+		}
+
+		for i := 0; i < subtreescount-1; i++ {
+			go func(index int, resultindex int) {
+				var leftnode, rightnode *node
+				select {
+				case leftnode = <-results[index]:
+					rightnode = <-results[index+1]
+				case rightnode = <-results[index+1]:
+					leftnode = <-results[index]
+				}
+				results[resultindex] <- &node{label: makeHash(leftnode, rightnode),
+					children: [2]*node{leftnode, rightnode}}
+			}(i*2, subtreescount+i)
+
+		}
+
+		rootnode = <-results[(1<<uint(height)-1)-1]
+	} else {
+		rootnode = &node{label: data, children: [2]*node{nil, nil}}
+	}
+
+	tree := &BTree{uint64(leafcount), rootnode, rootHash(uint64(leafcount), rootnode.label), datalen}
+
+	if validate {
+		err = tree.Validate()
+		if err != nil {
+			return nil, nil, 0, errors.New("Validation error")
+		}
+		if tree.Count() != uint64(leafcount) {
+			return nil, nil, 0, errors.New("Validation count error")
+		}
+	}
+	return tree, &Root{uint64(leafcount), tree.Root()}, leafcount, nil
+
+}
+
+// returns a node and the left over data not used by it
+func buildNode(data []byte, height int) (*node, []byte) {
+	if height == 0 || len(data) == 0 {
+		return nil, data
+	}
+	if height == 1 {
+		// leaf
+		return &node{label: data[0:segmentsize]}, data[segmentsize:]
+	}
+	n0, data := buildNode(data, height-1)
+	n1, data := buildNode(data, height-1)
+
+	hash := makeHash(n0, n1)
+	return &node{label: hash, children: [2]*node{n0, n1}}, data
+}
+
+func buildNode2(data [][]byte, height int) (*node, [][]byte) {
+	if height == 0 || len(data) == 0 {
+		return nil, data
+	}
+	if height == 1 {
+		// leaf
+		return &node{label: data[0]}, data[1:]
+	}
+	n0, data := buildNode2(data, height-1)
+	n1, data := buildNode2(data, height-1)
+
+	hash := makeHash(n0, n1)
+	return &node{label: hash, children: [2]*node{n0, n1}}, data
+}
+
+func splitData(data []byte, size int) [][]byte {
+	/* Splits data into an array of slices of len(size) */
+	count := len(data) / size
+	blocks := make([][]byte, 0, count)
+	for i := 0; i < count; i++ {
+		block := data[i*size : (i+1)*size]
+		blocks = append(blocks, block)
+	}
+	if len(data)%size != 0 {
+		blocks = append(blocks, data[len(blocks)*size:])
+	}
+	height := GetHeight(uint64(len(blocks)))
+	for i := len(blocks); i < (1 << uint(height)); i++ {
+		blocks = append(blocks, nil)
+	}
+	//
+	return blocks
+}
+
+type inclusionproofs struct {
+	proofs []inclusionproof
+	offset int
+	len    int
+}
+
+type inclusionproof struct {
+	proof  [][]byte
+	offset int
+	len    int
+	index  int
+}
+
+func (t *BTree) GetInclusionProofs(offset int, length int) (proofs inclusionproofs, err error) {
+
+	if offset+length > t.chunklen {
+
+		return proofs, errors.New(fmt.Sprintf("wrong offset+len %d  :chunklen:%d", offset+length, t.chunklen))
+	}
+
+	n := (offset%segmentsize+length)/segmentsize + 1
+
+	proofs.proofs = make([]inclusionproof, n+1)
+	var index int = 0
+	var segment = offset / segmentsize
+	for i := segment; i <= segment+n; i++ {
+		proofs.proofs[index], err = t.InclusionProof(i)
+		index++
+	}
+	proofs.len = length
+	proofs.offset = offset
+	return proofs, nil
+}
+
+// Return a [][]byte needed to prove the gkf of the item at the passed index
+// The payload of the item at index is the first value in the proof
+func (t *BTree) InclusionProof(index int) (proof inclusionproof, err error) {
+	if uint64(index) >= t.count {
+		return proof, errors.New("Invalid index: too large")
+	}
+	if index < 0 {
+		return proof, errors.New("Invalid index: negative")
+	}
+	h := GetHeight(t.count)
+	proof.proof, err = proveNode(h, t.root, index)
+	proof.offset = index * segmentsize
+	proof.len = segmentsize
+	proof.index = index
+	return proof, err
+}
+
+func proveNode(height int, n *node, index int) ([][]byte, error) {
+	if height == 1 {
+		if index != 0 {
+			return nil, errors.New("Invalid index: non 0 for final node")
+		}
+		return [][]byte{n.label}, nil
+	}
+	childIndex := index >> uint(height-2)
+	nextIndex := index & (^(1 << uint(height-2)))
+	b, _ := proveNode(height-1, n.children[childIndex], nextIndex)
+	otherChildIndex := (childIndex + 1) % 2
+	if n.children[otherChildIndex] != nil {
+		b = append(b, n.children[otherChildIndex].label)
+	}
+	return b, nil
+}
+
+// The Root of a merkle tree for a client that does not store the tree
+type Root struct {
+	Count uint64
+	Base  []byte
+}
+
+func (r *Root) CheckProofs(h Hasher, proofs inclusionproofs) (bool, error) {
+	n := (proofs.offset%segmentsize+proofs.len)/segmentsize + 1
+
+	for i := 0; i < n; i++ {
+		ok, err := r.CheckProof(h, proofs.proofs[i].proof, proofs.proofs[i].index)
+		if (ok == false) || (err != nil) {
+			return ok, err
+		}
+	}
+	return true, nil
+}
+
+// Proves theof an element at the given index with the value thats the first entry in proof
+func (r *Root) CheckProof(h Hasher, proof [][]byte, index int) (bool, error) {
+	hashFunc = h
+	theight := GetHeight(r.Count)
+	var root, ok, err = checkNode(theight, proof, uint64(index), r.Count)
+	base := rootHash(r.Count, root)
+	return ok && bytes.Equal(r.Base, base), err
+}
+
+func checkNode(height int, proof [][]byte, index uint64, count uint64) (hash []byte, ok bool, err error) {
+	if len(proof) == 0 {
+		return nil, false, errors.New("checkNode : proof is empty")
+	}
+	if count <= index {
+		fmt.Println("bad count", count, index)
+		return nil, false, fmt.Errorf("bad count %d at index %d", count, index)
+	}
+
+	if height == 1 {
+		if index != 0 || len(proof) != 1 {
+			fmt.Println("BAD", index, proof)
+			return nil, false, fmt.Errorf("BAD %d %d", index, proof)
+		}
+		return proof[0], true, nil
+	}
+
+	childIndex := index >> uint(height-2)
+	mask := uint64(^(1 << uint(height-2)))
+	nextIndex := index & mask
+
+	var data []byte
+	//var ok bool
+
+	h := hashFunc()
+	h.Reset()
+	//	h:=hashFunc.New()
+	var nextCount uint64
+	last := len(proof) - 1
+	if childIndex == 1 {
+		nextCount = count & mask
+		h.Write(proof[last])
+		data, ok, err = checkNode(height-1, proof[:last], nextIndex, nextCount)
+		h.Write(data)
+	} else {
+		nextCount = count
+		if count > ^mask {
+			nextCount = ^mask
+		}
+		if count == nextCount {
+			data, ok, err = checkNode(height-1, proof, nextIndex, nextCount)
+			h.Write(data)
+		} else {
+			data, ok, err = checkNode(height-1, proof[:last], nextIndex, nextCount)
+			h.Write(data)
+			h.Write(proof[last])
+		}
+	}
+
+	hash = h.Sum(make([]byte, 0))
+	return hash, ok, nil
+}
+
+// BMTHash defines the interface to hash functions that
+type BMTHash interface {
+	// Write absorbs more data into the hash's state. It panics if input is
+	// written to it after output has been read from it.
+	io.Writer
+
+	// Read reads more output from the hash; reading affects the hash's
+	// state.
+	// It never returns an error.
+	io.Reader
+
+	// Clone returns a copy of the BMTHash in its current state.
+	Clone() BMTHash
+
+	// Reset resets the BMTHash to its initial state.
+	Reset()
+}
+
+// Reset clears the internal state
+func (d *state) Reset() {
+	d.root = Root{Count: 0, Base: nil}
+	d.btree = BTree{count: 0, root: nil, rootHash: nil}
+}
+
+// Write absorbs more data into the hash's state.
+func (d *state) Write(p []byte) (written int, err error) {
+
+	tree, r, count, err1 := BuildBMT(hashFunc, p, true)
+	d.btree = *tree
+	d.root = *r
+
+	if err1 != nil {
+		err = errors.New("bmt write error")
+	}
+
+	return count, err
+}
+
+// Sum return the root hash of the BMT
+func (d *state) Sum(in []byte) []byte {
+	return d.root.Base
+}
+
+// BlockSize returns the rate of sponge underlying this hash function.
+func (d *state) BlockSize() int { return 0 }
+
+// Size returns the output size of the hash function in bytes.
+func (d *state) Size() int { return 32 }
+
+// NewBMTSHA3 creates a new BMT hash
+func NewBMTSHA3() hash.Hash {
+	tmpbtree := BTree{count: 0, root: nil, rootHash: nil}
+	troot := Root{Count: 0, Base: nil}
+	return &state{btree: tmpbtree, root: troot}
+}

swarm/storage/binarymerkle_test.go

@@ -0,0 +1,184 @@
+package storage
+
+import (
+	"fmt"
+	"log"
+	"math/rand"
+	"testing"
+	"time"
+
+	"github.com/ethereum/go-ethereum/crypto/sha3"
+)
+
+func TestBuildBMT(t *testing.T) {
+	for n := 0; n <= 4096; n += 1 {
+		fmt.Println("chunksize", n)
+		testBuildBMTprv(n, t)
+	}
+}
+
+func testBuildBMTprv(n int, t *testing.T) {
+
+	data := make([]byte, n)
+	tdata := testDataReader(n)
+	tdata.Read(data)
+
+	var tree *BTree
+	var r *Root
+	var count int
+	var err1 error
+	start := time.Now()
+	tree, r, count, err1 = BuildBMT(sha3.NewKeccak256, data, true)
+	elapsed := time.Since(start)
+	log.Printf("n=%d took %s", n, elapsed)
+
+	if err1 != nil {
+		fmt.Println(tree, r, count, err1)
+		return
+	}
+	// for i := 0; i < count; i++ {
+	// 	p, err := tree.InclusionProof(i)
+	// 	if err != nil {
+	// 		fmt.Println("proof failed ", i, err.Error())
+	// 		continue
+	// 	}
+	// 	ok, err := r.CheckProof(sha3.NewKeccak256, p.proof, i)
+	//
+	// 	if !ok || (err != nil) {
+	// 		t.Errorf("proof %d failed", i)
+	// 	}
+	// }
+
+	offset := rand.Intn(n)
+	length := rand.Intn((n-offset+1)-1) + 1
+	p, err := tree.GetInclusionProofs(offset, length)
+	if err != nil {
+		t.Errorf("proof %d failed %s", offset, err)
+		return
+
+	}
+
+	ok, err := r.CheckProofs(sha3.NewKeccak256, p)
+
+	if !ok || (err != nil) {
+		t.Errorf("proof  failed %s", err)
+	} else {
+		fmt.Println("proofs ok for offset", offset, "lenght", length, "chunksize", n)
+	}
+
+	// ok, err := r.CheckProof(sha3.NewKeccak256, p.proof, i)
+	//
+	// if !ok || (err != nil) {
+	// 	t.Errorf("proof %d failed", i)
+	// }
+
+	fmt.Println("done")
+}
+
+func benchmarkBuildBMT(n int, t *testing.B) {
+	//t.ReportAllocs()
+	tdata := testDataReader(n)
+	data := make([]byte, n)
+	tdata.Read(data)
+
+	//reader := bytes.NewReader(data)
+
+	var tree *BTree
+	var r *Root
+	var count int
+	var err1 error
+	//	blocks := splitData(data, 32)
+	t.ReportAllocs()
+	t.ResetTimer()
+	for i := 0; i < t.N; i++ {
+
+		tree, r, count, err1 = BuildBMT(sha3.NewKeccak256, data, false)
+
+		if err1 != nil {
+			fmt.Println(err1, tree, r, count)
+			return
+		}
+	}
+}
+
+func benchmarkSHA3(n int, t *testing.B) {
+
+	data := make([]byte, n)
+	tdata := testDataReader(n)
+	tdata.Read(data)
+	hashFunc = sha3.NewKeccak256
+
+	t.ReportAllocs()
+	t.ResetTimer()
+
+	h := hashFunc()
+	for i := 0; i < t.N; i++ {
+
+		h.Reset()
+		h.Write(data)
+		//binary.Write(h, binary.LittleEndian, count)
+		h.Sum(nil)
+
+	}
+
+}
+
+func BenchmarkBuildBMT_4k(t *testing.B)   { benchmarkBuildBMT(4096, t) }
+func BenchmarkBuildBMT_2k(t *testing.B)   { benchmarkBuildBMT(4096/2, t) }
+func BenchmarkBuildBMT_1k(t *testing.B)   { benchmarkBuildBMT(4096/4, t) }
+func BenchmarkBuildBMT_512b(t *testing.B) { benchmarkBuildBMT(4096/8, t) }
+func BenchmarkBuildBMT_256b(t *testing.B) { benchmarkBuildBMT(4096/16, t) }
+func BenchmarkBuildBMT_128b(t *testing.B) { benchmarkBuildBMT(4096/64, t) }
+
+func BenchmarkBuildSHA3_4k(t *testing.B)   { benchmarkSHA3(4096, t) }
+func BenchmarkBuildSHA3_2k(t *testing.B)   { benchmarkSHA3(4096/2, t) }
+func BenchmarkBuildSHA3_1k(t *testing.B)   { benchmarkSHA3(4096/4, t) }
+func BenchmarkBuildSHA3_512b(t *testing.B) { benchmarkSHA3(4096/8, t) }
+func BenchmarkBuildSHA3_256b(t *testing.B) { benchmarkSHA3(4096/16, t) }
+
+func BenchmarkBuildNagiBinaryMerkle_4k(t *testing.B) {
+	n := 4096
+	data := make([]byte, n)
+	tdata := testDataReader(n)
+	tdata.Read(data)
+	hashFunc = sha3.NewKeccak256
+
+	t.ReportAllocs()
+	t.ResetTimer()
+
+	//h := hashFunc()
+	for i := 0; i < t.N; i++ {
+
+		BinaryMerkle(data, sha3.NewKeccak256)
+
+	}
+
+}
+
+//func BenchmarkBinaryMerkleTree(t *testing.B) { benchmarkBMT(4096, t) }
+
+// This implementation does not take advantage of any paralellisms and uses
+// far more memory than necessary, but it is easy to see that it is correct.
+// It can be used for generating test cases for optimized implementations.
+
+func BinaryMerkle(chunk []byte, hasher Hasher) []byte {
+	hash := hasher()
+	section := 2 * hash.Size()
+	l := len(chunk)
+	if l > section {
+		n := l / section
+		r := l - n*section
+		hash.Write(chunk[0:r])
+		next := hash.Sum(nil)
+		for r < l {
+			hash.Reset()
+			hash.Write(chunk[r : r+section])
+			next = hash.Sum(next)
+			r += section
+		}
+		return BinaryMerkle(next, hasher)
+	} else {
+		hash.Write(chunk)
+		return hash.Sum(nil)
+	}
+}

swarm/storage/chunker.go

@@ -51,7 +51,8 @@ data_{i} := size(subtree_{i}) || key_{j} || key_{j+1} .... || key_{j+n-1}
 */
 
 const (
-	defaultHash = "SHA3" // http://golang.org/pkg/hash/#Hash
+	//defaultHash = "SHA3"
+	defaultHash = "BMTSHA3" // http://golang.org/pkg/hash/#Hash
 	// defaultHash           = "SHA256" // http://golang.org/pkg/hash/#Hash
 	defaultBranches int64 = 128
 	// hashSize     int64 = hasherfunc.New().Size() // hasher knows about its own length in bytes

swarm/storage/types.go

@@ -83,6 +83,8 @@ func MakeHashFunc(hash string) Hasher {
 		return crypto.SHA256.New
 	case "SHA3":
 		return sha3.NewKeccak256
+	case "BMTSHA3":
+		return NewBMTSHA3
 	}
 	return nil
 }