Class: WordHash

Inherits:
Object
  • Object
show all
Defined in:
lib/word_hash.rb

Overview

Transforms hex digests to human-readable strings.

The format of these strings will look something like: ‘victor-bacon-zulu-lima`. The output is obtained by compressing the input digest to a fixed number of bytes, then mapping those bytes to one of 256 words. A default wordlist is provided, but you can override this if you prefer.

As long as you use the same wordlist, the output will be consistent (i.e. the same digest will always render the same representation).

Constant Summary collapse

DEFAULT_WORDLIST = 
%w(
  ack alabama alanine alaska alpha angel apart april arizona arkansas artist
  asparagus aspen august autumn avocado bacon bakerloo batman beer berlin
  beryllium black blossom blue bluebird bravo bulldog burger butter
  california carbon cardinal carolina carpet cat ceiling charlie chicken
  coffee cola cold colorado comet connecticut crazy cup dakota december
  delaware delta diet don double early earth east echo edward eight eighteen
  eleven emma enemy equal failed fanta fifteen fillet finch fish five fix
  floor florida football four fourteen foxtrot freddie friend fruit gee
  georgia glucose golf green grey hamper happy harry hawaii helium high hot
  hotel hydrogen idaho illinois india indigo ink iowa island item jersey jig
  johnny juliet july jupiter kansas kentucky kilo king kitten lactose lake
  lamp lemon leopard lima lion lithium london louisiana low magazine
  magnesium maine mango march mars maryland massachusetts may mexico michigan
  mike minnesota mirror mississippi missouri mobile mockingbird monkey
  montana moon mountain muppet music nebraska neptune network nevada nine
  nineteen nitrogen north november nuts october ohio oklahoma one orange
  oranges oregon oscar oven oxygen papa paris pasta pennsylvania pip pizza
  pluto potato princess purple quebec queen quiet red river robert robin
  romeo rugby sad salami saturn september seven seventeen shade sierra single
  sink six sixteen skylark snake social sodium solar south spaghetti speaker
  spring stairway steak stream summer sweet table tango ten tennessee tennis
  texas thirteen three timing triple twelve twenty two uncle undress uniform
  uranus utah vegan venus vermont victor video violet virginia washington
  west whiskey white william winner winter wisconsin wolfram wyoming xray
  yankee yellow zebra zulu
)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(wordlist = DEFAULT_WORDLIST) ⇒ WordHash

Returns a new instance of WordHash.



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# File 'lib/word_hash.rb', line 44

def initialize(wordlist = DEFAULT_WORDLIST)
  fail ArgumentError, 'Wordlist must have exactly 256 items' unless
    wordlist.length == 256

  @wordlist = wordlist
end

Instance Attribute Details

#wordlist ⇒ Object (readonly)

Returns the value of attribute wordlist.



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# File 'lib/word_hash.rb', line 14

def wordlist
  @wordlist
end

Instance Method Details

#compress(bytes, target) ⇒ Object

Compress a list of byte values to a fixed target length.

Attempting to compress a smaller number of bytes to a larger number is an error



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# File 'lib/word_hash.rb', line 56

def compress(bytes, target)
  fail ArgumentError, 'Fewer input bytes than requested output' if
    target > bytes.size

  slices = slice_bytes bytes, target

  # XOR checksum-like compression
  slices.map do |slice|
    slice.reduce :^
  end
end

#humanize(hexdigest, words = 4, separator = '-') ⇒ Object

Humanize a given hexadecimal digest.

Change the number of words output by specifying ‘words`. Change the word separator with `separator`.



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# File 'lib/word_hash.rb', line 72

def humanize(hexdigest, words = 4, separator = '-')
  bytes = hexdigest.split('')
                   .each_slice(2).to_a
  bytes.pop if bytes.last.size == 1

  bytes = bytes.map { |byte| byte.join('').to_i 16 }

  wordify_bytes(bytes, words, separator)
end

#uuid(*args) ⇒ Object

Generate a UUID with a human-readable representation.

Returns ‘[human_repr, full_digest]`. Accepts the same keyword arguments as `humanize`



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# File 'lib/word_hash.rb', line 86

def uuid(*args)
  digest = SecureRandom.uuid.delete '-'
  word_hash = humanize digest, *args
  [digest, word_hash]
end