Merkle 
Builds a Merkle tree using either sha1, md5 or clear algorithm.
Usage
Build a Merkle tree
var merkle = require('merkle');
var tree = merkle(['a', 'b', 'c', 'd', 'e'], 'sha1').process();Extract tree data
You can get tree root using:
> tree.root();
'114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9'Get tree depth:
> tree.depth();
3Get tree number of levels (depth + level of leaves):
> tree.levels();
4Get tree number of nodes
> tree.nodes();
6Get a tree level nodes:
> tree.level(0);
['114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9']
> tree.level(1);
[
'585DD1B0A3A55D9A36DE747EC37524D318E2EBEE',
'58E6B3A414A1E090DFC6029ADD0F3555CCBA127F'
]
> tree.level(2);
[
'F4D9EEA3797499E52CC2561F722F935F10365E40',
'734F7A56211B581395CB40129D307A0717538088',
'58E6B3A414A1E090DFC6029ADD0F3555CCBA127F'
]
...Using different hash algorithms
var sha1tree = merkle(['a', 'b', 'c', 'd', 'e'], 'sha1').process();
var md5tree = merkle(['a', 'b', 'c', 'd', 'e'], 'md5').process();
var cleartree = merkle(['a', 'b', 'c', 'd', 'e'], 'clear').process();
> sha1tree.root();
'114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9'
> md5tree.root();
'064705BD78652C090975702C9E02E229'
> cleartree.root();
'ABCDE'Install globally for merkle command
Installing it globally will introduce the merkle command:
$ sudo npm install -g merkle
$ merkle a
86F7E437FAA5A7FCE15D1DDCB9EAEAEA377667B8By default, merkle returns the root of the merkle tree:
$ merkle a b c d e
114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9But 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
58E6B3A414A1E090DFC6029ADD0F3555CCBA127FOr even all levels:
merkle a b c d e --all
114B6E61CB5BB93D862CA3C1DFA8B99E313E66E9
585DD1B0A3A55D9A36DE747EC37524D318E2EBEE
58E6B3A414A1E090DFC6029ADD0F3555CCBA127F
F4D9EEA3797499E52CC2561F722F935F10365E40
734F7A56211B581395CB40129D307A0717538088
58E6B3A414A1E090DFC6029ADD0F3555CCBA127F
86F7E437FAA5A7FCE15D1DDCB9EAEAEA377667B8
E9D71F5EE7C92D6DC9E92FFDAD17B8BD49418F98
84A516841BA77A5B4648DE2CD0DFCB30EA46DBB4
3C363836CF4E16666669A25DA280A1865C2D2874
58E6B3A414A1E090DFC6029ADD0F3555CCBA127FYou can also change of hash algorithm:
$ merkle a b c d e -h md5
064705BD78652C090975702C9E02E229
$ merkle a b c d e -h clear
ABCDEAnd 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 nodesFinally, 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.
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