hypercore-xsalsa20-onwrite-hook

hypercore-xsalsa20-onwrite-hook

A write hook to decrypt data using a xsalsa20 cipher into a Hypercore storage when replicating from peers.

Installation

$ npm install hypercore-xsalsa20-onwrite-hook

Usage

const nonces = ram() // or any `random-access-storage` compliant object
const onwrite = hook(nonces, sharedSecret)

Example

const replicate = require('hypercore-replicate')
const hypercore = require('hypercore')
const crypto = require('hypercore-crypto')
const hook = require('hypercore-xsalsa20-onwrite-hook')
const ram = require('random-access-memory')

const key = crypto.randomBytes(32)

const { publicKey, secretKey } = crypto.keyPair()
const nonces = ram()

const feed = hypercore(ram, publicKey, {
  secretKey,
  onwrite: hook(nonces, key)
})

const copy = hypercore(ram, publicKey, {
  onwrite: hook(nonces, key)
})

feed.append(Buffer.from('hello'), (err) => {
  feed.head(console.log) // ciphertext
})

replicate(feed, copy, (err) => {
  copy.head(console.log) // plaintext
})

API

const onwrite = hook(nonceStorage, sharedKey)

Creates a onwrite() hook for a Hypercore feed that uses the xsalsa20 cipher to encipher or decipher blocks in a Hypercore feed. Blocks that are written to a Hypercore feed are encrypted detached from the nonce used for encryption. Nonces are written to a user supplied "nonce storage" which can be reused for deciphering blocks appended to a Hypercore feed.

This function preserves block sizes but requires an external storage for nonces (nonceStorage). Users should provide a random-access-storage compliant instance or a factory function that returns one.

License

MIT