siphash24-stream

SipHash24 sign and verify streams powered by a seedable keystream.

Get it!

npm install --save siphash24-stream

Usage

Create both signing and verifying streams by supplying a variable-length symmetric key that is used for seeding an internal keystream.

Run node ./usage.js:

var crypto = require('crypto')
var stream = require('stream')
var sip = require('siphash24-stream')

var DELIMITER = Buffer.from([ 0, 4, 1, 9, 4, 1, 9, 0 ])

var NSA = Buffer.concat([ // pac
  crypto.randomBytes(8),  // bad mac
  Buffer.from('nsa pac'), // msg
  DELIMITER
])

var shared = '419' // shared secret, symmetric key
var opts = { algo: 'alea', delimiter: DELIMITER } // default options
var alice = sip.createSigningStream(shared, opts) // alice signs
var bob = sip.createVerifyingStream(shared, opts) // bob verifies
var thru = new stream.PassThrough()               // some sort of socket

function onpac (info, chunk) {
  console.log(info, chunk.toString())
}

alice.pipe(thru).pipe(bob) // alice writes, bob reads

thru.on('data', onpac.bind(null, 'bob input:'))
bob.on('data', onpac.bind(null, 'bob ok:'))
bob.on('dropping', onpac.bind(null, 'bob dropping:'))

alice.write('push all dirty money overseas')
thru.write(NSA) // being intercepted
alice.end('and buy uzis')

Note that only legit msg packs pass thru the verifying end, in this case bob.

API

var sign = sip.createSigningStream(init[, opts])

Create a transform stream that signs all its throughput with a SipHash24 mac. init is the seed for a random byte generator used as key stream.

Options default to:

{
  algo: 'alea',
  delimiter: Buffer.from([ 0, 4, 1, 9, 4, 1, 9, 0 ])
}

opts.algo indicates the algorithm to use for the internal random number generator. Check out seedrandom for a list of supported algorithms. opts.delimiter is the message delimiter, must be a buffer.

var verify = sip.createVerifyingStream(init[, opts])

Create a transform stream that verifies all its throughput against a SipHash24 mac. Bad chunks are rejected and not passed on, not pushed any further, but emitted with the dropping event.

var { sign, verify } = sip.createSipHash24Streams(init[, opts])

Create a SipHash24 sign and verify stream duplet.

verify.on('dropping', ondropping)

Emitted with every chunk that will not be pushed further. Use this if you wish to check dropouts. Calling back like ondropping(chunk).

License

MIT