merkle-dir

Create merkle trees from directories.

Example

Let's create a merkle tree from the test/fixtures folder:

var merkle = require('merkle-dir');

merkle(__dirname, function(err, tree) {
  console.log(JSON.stringify(tree, null, '  '));
});

And the tree is:

$ node example.js
{
  "path": "",
  "hash": "79d8ca8a1c6e37271a7c846246a0035e46cf3705a0024d01f830bc77c9e7c6a7",
  "tree": [
    {
      "path": "a",
      "hash": "bbfadafe6ae91a4b0311ad83ceac22e965ce7efd181c493e0d2339197449d769",
      "tree": [
        {
          "path": "a/file.txt",
          "hash": "197e199545eca4b58d335b7e671871a63e4e5b3ca6361cfa9605b654bc3bbfa1"
        }
      ]
    },
    {
      "path": "b",
      "hash": "e9e3596a701f0edb0c80e9d0bd147e223c1f965f0aef388844222c1140fbaec3",
      "tree": [
        {
          "path": "b/file.txt",
          "hash": "f1523727794b3bed803486a4b10b46962696e0401bcf94f995078577cbbff3cf"
        }
      ]
    },
    {
      "path": "c",
      "hash": "bbfadafe6ae91a4b0311ad83ceac22e965ce7efd181c493e0d2339197449d769",
      "tree": [
        {
          "path": "c/ahoi.txt",
          "hash": "197e199545eca4b58d335b7e671871a63e4e5b3ca6361cfa9605b654bc3bbfa1"
        }
      ]
    }
  ]
}

API

merkle(directory, fn)

Create a merkle tree covering directory and call fn with the possible error and the tree.

Nodes have those keys:

• path: the path relative to the root directory
• hash: the hex encoded sha256 hash of the file or its subtree
• tree: the subtree, exists only if the node is a directory

Use cases

• hash an entire directory: If you just use tree.hash you get the hash of an entire directory and all its folders and subdirectories.
• diff directories: Traverse the directory breadth-first to quickly find out what files differ, in O(|V| + |E|) time.

TODO

• what to hash with file nodes(#1)
• handle links (#2)
• move to a binary tree? depends on diffing algorithm (#3)

Installation

With npm do:

npm install merkle-dir

License

(MIT)

Copyright (c) 2013 Julian Gruber <julian@juliangruber.com>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.