content-hash

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

⚠️ The EIP 1577 spec can change rapidlly, expect this lib to do the same !

Here you can find a live demo of this package.

• link to npm
• link to Github

📥 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.

📕 API

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

contentHash.Types

This is an object that defines the codec type constants.

• contentHash.Types.swarm : codec for Swarm content hashes = 0x00
• contentHash.Types.ipfs : codec for IPFS content hashes = 0x01

contentHash.decode( string ) -> string

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

const encoded = '01122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'

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

contentHash.fromIpfs( string ) -> string

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

const ipfsHash = 'QmRAQB6YaCyidP37UdDnjFY5vQuiBrcqdyoW1CuDgwxkD4'

const contentH = contentHash.fromIpfs(ipfsHash)
// '01122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'

contentHash.fromSwarm( swarmHash ) -> string

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

const swarmHash = 'd1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

const contentH = contentHash.fromSwarm(swarmHash)
// '00d1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

contentHash.fromBuffer( codec, buffer ) -> string

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

const value = 'd1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

const contentH = contentHash.fromBuffer('00', value)
// '00d1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

contentHash.getCodecType( contentHash ) -> string

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

const encoded = '01122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'

const codec = contentHash.getCodecType(encoded) // '01'
// here codec is equal to contentHash.Types.ipfs

contentHash.isHashOfType( contentHash, type ) -> boolean

This function takes a content hash as a hex string and a codec as a contentHash.Types and returns a boolean depending on wether or not the content hash has the same codec as the type.

const encoded = '01122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'

contentHash.isHashOfType(encoded, contentHash.Types.ipfs) // true

🚫 contentHash.getCodec( contentHash ) -> string

DEPRECATED : will be reomved soon, use contentHash.getCodecType( contentHash ) -> string instead

This function takes a content hash as a hex string and returns the type of codec used as a string. The return value can be swarm, ipfs, if the codec is unknown this function will throw a UnknownCodec error.

const encoded = '01122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'

const codec = contentHash.getCodec(encoded) // 'ipfs'

const badValue = 'ff122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'
const codec2 = contentHash.getCodec(badValue)
// throw UnknownCodec : codec : ff , content-hash : 122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f

🚫 contentHash.isIpfs( contentHash ) -> boolean

DEPRECATED : will be reomved soon, use contentHash.isHashOfType( contentHash, type ) -> boolean instead

This function takes a content hash as a hex string and returns a boolean, it will return true only if the content hash prefixed with the IPFS codec. (this function never throws)

const encoded = '01122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f'

const codec = contentHash.isIpfs(encoded) // true

🚫 contentHash.isSwarm( contentHash ) -> boolean

DEPRECATED : will be reomved soon, use contentHash.isHashOfType( contentHash, type ) -> boolean instead

This function takes a content hash as a hex string and returns a boolean, it will return true only if the content hash prefixed with the Swarm codec. (this function never throws)

const encoded = '00d1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

const codec = contentHash.isSwarm(encoded) // true

🚫 contentHash.isUnknown( contentHash ) -> boolean

DEPRECATED : will be reomved soon, use contentHash.isHashOfType( contentHash, type ) -> boolean instead

This function takes a content hash as a hex string and returns a boolean, it will return true only if the content hash prefixed with an unknown codec. (this function never throws)

const encoded = 'ffd1de9994b4d039f6548d191eb26786769f580809256b4685ef316805265ea162'

const codec = contentHash.isUnknown(encoded) // true

👨‍💻 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 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