content-hash

What is content-hash?

The content-hash npm package is used to generate content hashes for various types of content. This can be useful for caching, versioning, and ensuring data integrity.

What are content-hash's main functionalities?

Generate Hash for a String

This feature allows you to generate a hash for a given string. The hash can be used to uniquely identify the content of the string.

const contentHash = require('content-hash');
const hash = contentHash('Hello, World!');
console.log(hash);

Generate Hash for a Buffer

This feature allows you to generate a hash for a Buffer object. This is useful for binary data or files.

const contentHash = require('content-hash');
const buffer = Buffer.from('Hello, World!');
const hash = contentHash(buffer);
console.log(hash);

Generate Hash for a File

This feature allows you to generate a hash for a file by reading its contents into a Buffer and then hashing it. This is useful for ensuring file integrity.

const fs = require('fs');
const contentHash = require('content-hash');
const filePath = 'path/to/your/file.txt';
const fileBuffer = fs.readFileSync(filePath);
const hash = contentHash(fileBuffer);
console.log(hash);

Other packages similar to content-hash

hasha

The hasha package is a versatile hashing library that supports multiple algorithms like MD5, SHA-1, and SHA-256. It is similar to content-hash but offers more flexibility in terms of hashing algorithms.

crypto

The crypto package is a built-in Node.js module that provides cryptographic functionality, including hashing. It is more low-level compared to content-hash but offers extensive features for cryptographic operations.

object-hash

The object-hash package is designed to hash JavaScript objects. It is similar to content-hash but specifically optimized for object hashing, making it useful for generating unique identifiers for complex data structures.

README

content-hash

This is a simple package made for encoding and decoding content hashes as specified in the EIP 1577. This package will be useful for every Ethereum developer wanting to interact with EIP 1577 compliant ENS resolvers.

Here you can find a live demo of this package.

• link to npm
• link to Github

🔠 Supported Codec

• swarm-ns
• ipfs-ns
• ipns-ns
• Every other codec supported by multicodec will be encoded by default in utf-8.

You can see the full list of codec supported here

📥 Install

• via npm :

  $> npm install content-hash
  

• via Github : Download or clone this repo, then install the dependencies.

  $> git clone https://github.com/pldespaigne/content-hash.git
  $> cd content-hash
  $> npm install
  

For browser only usage, installation is not required.

🛠 Usage

Import the module in order to use it :

• NodeJS :

  const contentHash = require('content-hash')
  

• Browser :

  <!--From CDN-->
  <script type="text/javascript" src="https://unpkg.com/content-hash/dist/index.js"></script>
  
  <!--From local module-->
  <script type="text/javascript" src="path/to/dist/index.js"></script>
  

To rebuild the browser version of the package run npm run build into the root folder. Don't forget to also run npm run lint and npm test before building !

📕 API

All hex string inputs can be prefixed with 0x, but it's not mandatory.

⚠️ All outputs are NOT prefixed with 0x

contentHash.decode( contentHash ) -> string

This function takes a content hash as a hex string and returns the decoded content as a string.

const encoded = 'e3010170122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'

const content = contentHash.decode(encoded)
// 'QmRAQB6YaCyidP37UdDnjFY5vQuiBrcqdyoW1CuDgwxkD4'

contentHash.fromIpfs( ipfsHash ) -> string

This function takes an IPFS address as a base58 encoded string and returns the encoded content hash as a hex string.

this function just call contentHash.encode() under the hood

const ipfsHash = 'QmRAQB6YaCyidP37UdDnjFY5vQuiBrcqdyoW1CuDgwxkD4'

const contentH = contentHash.fromIpfs(ipfsHash)
// 'e3010170122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'

contentHash.fromSwarm( swarmHash ) -> string

This function takes a Swarm address as a hex string and returns the encoded content hash as a hex string.

this function just call contentHash.encode() under the hood

const swarmHash = 'd1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

const contentH = contentHash.fromSwarm(swarmHash)
// 'e40101701b20d1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

contentHash.encode( codec, value) -> string

This function takes a supported codec as a string and a value as a string and returns coresponding content hash as a hex string.

const onion = 'zqktlwi4fecvo6ri'
contentHash.encode('onion', onion);
// 'bc037a716b746c776934666563766f367269'

contentHash.getCodec( contentHash ) -> string

This function takes a content hash as a hex string and returns the codec as a hex string.

const encoded = 'e40101701b20d1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

const codec = contentHash.getCodec(encoded) // 'swarm-ns'
codec === 'ipfs-ns' // false

contentHash.helpers

This object contain the following helpers functions :

• cidV0ToV1Base32( ipfsHash ) -> string

  This function takes an ipfsHash and convert it to a CID v1 encoded in base32.

  const ipfs = 'QmYwAPJzv5CZsnA625s3Xf2nemtYgPpHdWEz79ojWnPbdG'
  
  const cidV1 = contentHash.helpers.cidV0ToV1Base32(ipfs)
  // 'bafybeibj6lixxzqtsb45ysdjnupvqkufgdvzqbnvmhw2kf7cfkesy7r7d4'
  

👨‍💻 Maintainer

• pldespaigne : github, twitter

🙌 Contributing

For any questions, discussions, bug report, or whatever I will be happy to answer through the issues or on my twitter 😁. PR (with tests) are also welcome !

📝 License

This project is licensed under the ISC License, you can find it here.

Note that the dependencies may have a different License