Nodes crypto module provides a rc4 cipher, but it lacks the ability to drop the first bytes from the keystream. This gist simply encrypts as many bytes as you want to drop, effectively causing those bytes from the keystream to get dropped. For full implementations of RC4Drop, please see: - https://github.com/gwjjeff/cryptojs - https://gist.githu…

rc4drop.js

crypto = require 'crypto'

class RC4
  constructor: (@key, drop) ->
    @cipher = crypto.createCipher 'rc4', key
    if drop > 0
      this.cipher.update new Buffer drop

  encrypt: (data) ->
    @cipher.update data

module.exports = RC4