Merkle

Builds a Merkle tree using either sha512, sha256, ripemd160, whirlpool, sha1, md5 or none algorithms.

hrishikeshio's fork

Modified the library to use soliditysha3. the tests are not updated and hence will fail. but the library should work fine.

Usage

Build a Merkle tree

var merkle = require('merkle');
var abcde = ['a', 'b', 'c', 'd', 'e'];

Sync style

var tree = merkle('sha1').sync(abcde);

Async style

merkle('sha1').async(abcde, function(err, tree){
  // ...
});

Stream style

// Stream style -- streams root hash
var merkleStreamRoot = merkle('sha1');
merkleStreamRoot.pipe(process.stdout);

// Stream style -- streams json tree
var es = require('event-stream');
var merkleStreamJson = merkle('sha1').json();
merkleStreamJson
  .pipe(es.stringify())
  .pipe(process.stdout);

abcde.forEach(function(letter){
    merkleStreamJson.write(letter);
});

merkleStreamJson.end();

// out:
// {"root":"114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9","depth":3,"levels":4,"nodes":6}

Working ONLY with lowercase

For historical reasons, hashes were systematically uppercased which could lead to wrong trees (see issue #8).

We've added an extra parameter to avoid this case alteration, so you can work exclusively with lowercase hashes:

var use_uppercase = false;
merkle('sha256', use_uppercase);

We plan to remove this syntax for v1.0.0 and always use lowercase hashes.

Extract tree data

You can get tree root using:

> tree.root();
'114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9'

Get tree depth:

> tree.depth();
3

Get tree number of levels (depth + level of leaves):

> tree.levels();
4

Get tree number of nodes

> tree.nodes();
6

Get a tree level nodes:

> tree.level(0);
['114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9']

> tree.level(1);
[
  '585DD1B0A3A55D9A36DE747EC37524D318E2EBEE',
  '58E6B3A414A1E090DFC6029ADD0F3555CCBA127F'
]

> tree.level(2);
[
  'F4D9EEA3797499E52CC2561F722F935F10365E40',
  '734F7A56211B581395CB40129D307A0717538088',
  '58E6B3A414A1E090DFC6029ADD0F3555CCBA127F'
]

...

Using different hash algorithms

var sha256tree= merkle('sha256').sync(abcde);
var sha1tree  = merkle('sha1').sync(abcde);
var md5tree   = merkle('md5').sync(abcde);
var cleartree = merkle('none').sync(abcde);

> sha256tree.root();
'16E6BEB3E080910740A2923D6091618CAA9968AEAD8A52D187D725D199548E2C'

> sha1tree.root();
'114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9'

> md5tree.root();
'064705BD78652C090975702C9E02E229'

> cleartree.root();
'ABCDE'

Install globally for merkle command

Installing it globally will introduce the merkle command (using sha1 as default):

$ sudo npm install -g merkle
$ merkle a
86F7E437FAA5A7FCE15D1DDCB9EAEAEA377667B8

By default, merkle returns the root of the merkle tree:

$ merkle a b c d e
114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9

But it can be asked for some level:

$ merkle a b c d e -l 0
114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9

$ merkle a b c d e -l 1
585DD1B0A3A55D9A36DE747EC37524D318E2EBEE
58E6B3A414A1E090DFC6029ADD0F3555CCBA127F

Or even all levels:

merkle a b c d e --all
114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9

585DD1B0A3A55D9A36DE747EC37524D318E2EBEE
58E6B3A414A1E090DFC6029ADD0F3555CCBA127F

F4D9EEA3797499E52CC2561F722F935F10365E40
734F7A56211B581395CB40129D307A0717538088
58E6B3A414A1E090DFC6029ADD0F3555CCBA127F

86F7E437FAA5A7FCE15D1DDCB9EAEAEA377667B8
E9D71F5EE7C92D6DC9E92FFDAD17B8BD49418F98
84A516841BA77A5B4648DE2CD0DFCB30EA46DBB4
3C363836CF4E16666669A25DA280A1865C2D2874
58E6B3A414A1E090DFC6029ADD0F3555CCBA127F

You can also change of hash algorithm:

$ merkle a b c d e -h md5
064705BD78652C090975702C9E02E229

$ merkle a b c d e -h clear
ABCDE

And just extract some computation statistics:

$ merkle a b c d e --count
4
=> Total number of levels

$ merkle a b c d e --nodes
6
=> Total number of nodes

Finally, you can ask for help:

$ merkle --help
Build a Merkle Tree and prints its values.
Usage: merkle [leaf...]

Options:
  --version    Prints version
  --help       Prints help
  -l, --level  Prints values of the given level. Defaults to 0 (root).
  -n, --nodes  Prints the number of nodes for the given leaves.
  -c, --count  Prints the number of levels for the given leaves.
  -h, --hash   Hash algorithm to apply on leaves. Values are 'sha1', 'md5' or 'none'.
  -a, --all    Prints all levels of Merkle tree, from leaves to root.
  --level                                                                              [default: 0]
  --hash                                                                               [default: "sha1"]

Concepts

Here is an example of Merkle tree with 5 leaves (taken from Tree Hash EXchange format (THEX)):

                   ROOT=H(H+E)
                    /        \
                   /          \
             H=H(F+G)          E
            /       \           \
           /         \           \
    F=H(A+B)         G=H(C+D)     E
    /     \           /     \      \
   /       \         /       \      \
  A         B       C         D      E


Note: H() is some hash function

Where A,B,C,D,E may be already hashed data. If not, those leaves are turned into hashed data (using either sha1, md5 or clear algorithm).

With such a tree structure, merkle considers the tree has exactly 6 nodes: [ROOT,H,E,F,G,E]. For a given level, nodes are just an array.

Adding a Z value would alter the E branch of the tree:

                    ROOT'=H(H+E')
                    /            \
                   /              \
             H=H(F+G)              E'
            /       \               \
           /         \               \
    F=H(A+B)          G=H(C+D)       E'=H(E+Z)
    /     \           /     \         /     \
   /       \         /       \       /       \
  A         B       C         D     E         Z

ROOT changed to ROOT', E to E', but H did not.

License

This software is provided under MIT license.