crosshash


Stable, cross-platform JSON serialization and hashing for Python and JavaScript.

Motivation

To make it possible to compare and hash JSON objects in a stable way across platforms.

Installation

$3


``bash
pip install crosshash
`

$3

![NPM](https://www.npmjs.com/package/crosshash)

`bash
npm install crosshash
`

Features




$3

The following functions are implemented in both Python and JavaScript and the output is guaranteed to be the same:

#### crossjson(obj) → str

- Sort keys alphabetically
- Ensure no unsafe numbers are present
- Serialize using the same format as JSON.stringify() (lowest common denominator)

#### crosshash(obj) → str

- Serialize the object with crossjson()
- Hash the resulting string with MD5




$3

Both Python and JavaScript implementations come with a CLI that can be used to generate stable JSON and hashes.

`bash
JSON='{"B":2,"C":[1,2,3],"A":1}'
[ $(crosshash-js --hash "$JSON") == $(crosshash-py --hash "$JSON") ] && echo 'It’s a match!'
[ $(crosshash-js --json "$JSON") == $(crosshash-py --json "$JSON") ] && echo 'It’s a match!'
`




Usage

$3

#### API

`python
from crosshash import crossjson, crosshash, CrossHashError, MAX_SAFE_INTEGER

obj = {'B': 2, 'C': [1, 2, 3], 'A': 1}

Generate stable JSON:

assert crossjson(obj) == '{"A":1,"B":2,"C":[1,2,3]}'

Generate stable hash:

assert crosshash(obj) == '12982c60a9a8829ea4eeb2e1e7e1e04e'

Throws CrossHashError:


crosshash({'A': MAX_SAFE_INTEGER + 1})
`

#### CLI

You can invoke crosshash.py directly or use python -m crosshash. The package also installs an executable called crosshash-py.

`bash
$ crosshash-py --json '{"B": 2, "C": [1, 2, 3], "A": 1}'
{"A":1,"B":2,"C":[1,2,3]}
`

`bash
$ crosshash-py --hash '{"B": 2, "C": [1, 2, 3], "A": 1}'
12982c60a9a8829ea4eeb2e1e7e1e04e
`




$3

#### API

The library runs in the browser and Node.js and comes with TypeScript definitions.

`javascript
const {crossjson, crosshash, CrossHashError} = require('crosshash')

const obj = {B: 2, C: [1, 2, 3], A: 1}

// Generate stable JSON:
assert(crossjson(obj) === '{"A":1,"B":2,"C":[1,2,3]}')

// Generate stable hash:
assert(crosshash(obj) === '12982c60a9a8829ea4eeb2e1e7e1e04e')

// Throws CrossHashError:
crosshash({A: Number.MAX_SAFE_INTEGER + 1})
`

#### CLI

You can invoke crosshash.js directly or using npx. The package also installs an executable called crosshash-js.

`bash
$ crosshash-js --json '{"B": 2, "C": [1, 2, 3], "A": 1}'
{"A":1,"B":2,"C":[1,2,3]}
`

`bash
$ crosshash-js --hash '{"B": 2, "C": [1, 2, 3], "A": 1}'
12982c60a9a8829ea4eeb2e1e7e1e04e
`

Test suite

To ensure consistency, the test suite invokes the Python and JavaScript implementations of crossjson() and crosshash() on the same data and compares the results.




Development

It should be fairly straightforward to add support for other languages.

`bash
git clone git@github.com:httpie/crosshash.git
cd ./crosshash
make install
make test
``