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https://github.com/celestiaorg/nmt
Namespaced Merkle Tree
https://github.com/celestiaorg/nmt
namespaced-merkle-tree
Last synced: 6 days ago
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Namespaced Merkle Tree
- Host: GitHub
- URL: https://github.com/celestiaorg/nmt
- Owner: celestiaorg
- License: apache-2.0
- Created: 2020-07-15T15:06:30.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2024-11-25T21:24:05.000Z (about 2 months ago)
- Last Synced: 2024-12-29T04:14:35.765Z (13 days ago)
- Topics: namespaced-merkle-tree
- Language: Go
- Size: 1.23 MB
- Stars: 118
- Watchers: 13
- Forks: 44
- Open Issues: 31
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-ccamel - celestiaorg/nmt - Namespaced Merkle Tree (Go)
README
# Namespaced Merkle Tree (NMT)
[](https://pkg.go.dev/github.com/celestiaorg/nmt)
A Namespaced Merkle Tree is
> [...] an ordered Merkle tree that uses a modified hash function
so that each node in the tree includes the range of
namespaces of the messages in all of the descendants
of each node. The leafs in the tree are ordered by the
namespace identifiers of the messages.
In a namespaced Merkle tree, each non-leaf node in
the tree contains the lowest and highest namespace
identifiers found in all the leaf nodes that are descendants of the non-leaf node, in addition to the hash of
the concatenation of the children of the node. This
enables Merkle inclusion proofs to be created that prove to a verifier that all the elements of the tree for
a specific namespace have been included in a Merkle
inclusion proof.
The concept was first introduced by [@musalbas] in the LazyLedger [academic paper].
## Example
```go
package main
import (
"bytes"
"crypto/sha256"
"fmt"
"github.com/celestiaorg/nmt"
"github.com/celestiaorg/nmt/namespace"
)
func main() {
// the tree will use this namespace size (number of bytes)
nidSize := 1
// the leaves that will be pushed
data := [][]byte{
append(namespace.ID{0}, []byte("leaf_0")...),
append(namespace.ID{0}, []byte("leaf_1")...),
append(namespace.ID{1}, []byte("leaf_2")...),
append(namespace.ID{1}, []byte("leaf_3")...)}
// Init a tree with the namespace size as well as
// the underlying hash function:
tree := nmt.New(sha256.New(), nmt.NamespaceIDSize(nidSize))
for _, d := range data {
if err := tree.Push(d); err != nil {
panic(fmt.Sprintf("unexpected error: %v", err))
}
}
// compute the root
root, err := tree.Root()
if err != nil {
panic(fmt.Sprintf("unexpected error: %v", err))
}
// the root's min/max namespace is the min and max namespace of all leaves:
minNS := nmt.MinNamespace(root, tree.NamespaceSize())
maxNS := nmt.MaxNamespace(root, tree.NamespaceSize())
if bytes.Equal(minNS, namespace.ID{0}) {
fmt.Printf("Min namespace: %x\n", minNS)
}
if bytes.Equal(maxNS, namespace.ID{1}) {
fmt.Printf("Max namespace: %x\n", maxNS)
}
// compute proof for namespace 0:
proof, err := tree.ProveNamespace(namespace.ID{0})
if err != nil {
panic("unexpected error")
}
// verify proof using the root and the leaves of namespace 0:
leafs := [][]byte{
append(namespace.ID{0}, []byte("leaf_0")...),
append(namespace.ID{0}, []byte("leaf_1")...),
}
if proof.VerifyNamespace(sha256.New(), namespace.ID{0}, leafs, root) {
fmt.Printf("Successfully verified namespace: %x\n", namespace.ID{0})
}
if proof.VerifyNamespace(sha256.New(), namespace.ID{2}, leafs, root) {
panic(fmt.Sprintf("Proof for namespace %x, passed for namespace: %x\n", namespace.ID{0}, namespace.ID{2}))
}
}
```
The above will create a Namespaced merkle tree with four leafs which looks like this:
Where `nid_0 = nid_1 = 0` and `nid_2 = nid_3 = 1` and `data_i = "leaf_i"` for `i = 0,...,3`.
## Related
This implementation was heavily inspired by the initial implementation in [celestiaorg/lazyledger-prototype](https://github.com/celestiaorg/lazyledger-prototype).
Non-endorsed implementations of NMT exist in other languages:
Language | Repo
---------|------------------------------------------------------------------
Rust | [Sovereign-Labs/nmt-rs](https://github.com/Sovereign-Labs/nmt-rs)
[academic paper]: https://arxiv.org/abs/1905.09274
[@musalbas]: https://github.com/musalbas
## Contributing
Markdown files must conform to [GitHub Flavored Markdown](https://github.github.com/gfm/). Markdown must be formatted with:
- [markdownlint](https://github.com/DavidAnson/markdownlint)
- [Markdown Table Prettifier](https://github.com/darkriszty/MarkdownTablePrettify-VSCodeExt)
## Audits
Date | Auditor | Report
----------|-----------------------------------------------|--------------------------------------------------------
2023/8/18 | [Informal Systems](https://informal.systems/) | [informal-systems.pdf](docs/audit/informal-systems.pdf)