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="https://github.com/pldespaigne/content-hash/raw/master/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
```javascript
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