Module: Crypto

Included in:

Cipher::ChaoCipher, Cipher::DisruptedTransposition, Cipher::Wheatstone, Key::Playfair, Key::SCKey, Key::TKey, Key::VICKey, Key::Wheatstone

Defined in:

lib/crypto_helper.rb

Overview

Defined Under Namespace

Classes: HoleArea

Constant Summary

BASE =

keyshuffle

Form an alphabet formed with a keyword, re-shuffle everything to make it less predictable (i.e. checkerboard effect)

Shuffle the alphabet a bit to avoid sequential allocation of the code numbers. This is actually performing a transposition with the word itself as key.

Regular rectangle

---

Key is ARABESQUE condensed into ARBESQU (len = 7) (height = 4) Let word be ARBESQUCDFGHIJKLMNOPTVWXYZ/-

First passes will generate

A RBESQUCDFGHIJKLMNOPTVWXYZ/- c=0 0 x 6 AC RBESQUDFGHIJKLMNOPTVWXYZ/- c=6 1 x 6 ACK RBESQUDFGHIJLMNOPTVWXYZ/- c=12 2 x 6 ACKV RBESQUDFGHIJLMNOPTWXYZ/- c=18 3 x 6 ACKVR BESQUDFGHIJLMNOPTWXYZ/- c=0 0 x 5 ACKVRD BESQUFGHIJLMNOPTWXYZ/- c=5 1 x 5 … ACKVRDLWBFMXEGNYSHOZQIP/UJT-

Irregular rectangle

---

Key is SUBWAY condensed info SUBWAY (len = 6) (height = 5)

S UBWAYCDEFGHIJKLMNOPQRTVXZ/- c=0 0 x 5 SC UBWAYDEFGHIJKLMNOPQRTVXZ/- c=5 1 x 5 SCI UBWAYDEFGHJKLMNOPQRTVXZ/- c=10 2 x 5 SCIO UBWAYDEFGHJKLMNPQRTVXZ/- c=15 3 x 5 SCIOX UBWAYDEFGHJKLMNPQRTVZ/- c=20 4 x 5 SCIOXU BWAYDEFGHJKLMNPQRTVZ/- c=0 0 x 4 … SCIOXUDJPZBEKQ/WFLR-AG YHMNTV c=1 1 x 1 SCIOXUDJPZBEKQ/WFLR-AGM YHNTV c=2 2 x 1 SCIOXUDJPZBEKQ/WFLR-AGMT YHNV c=3 3 x 1 SCIOXUDJPZBEKQ/WFLR-AGMTYHNV

'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

Instance Method Summary (collapse)

• - (Object) addmod10(a, b)

  addmod10.

• - (Object) chainadd(a)

  chainadd.

• - (Object) expand5to10(a)

  expand5to10.

• - (Object) find_hole(kw, ph = 'AT ONE SIR')

  find_hole.

• - (Object) keyshuffle(key, base = BASE)
• - (Object) normalize(a)

  normalize.

• - (Object) p1_encode(p1, p2)

  p1_encode.

• - (Object) str_to_numeric(str)

  str_to_numeric.

• - (Object) submod10(a, b)

  submod10.

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# File 'lib/crypto_helper.rb', line 244

def addmod10(a, b)
  raise DataError if a.length != b.length
  (0..a.length-1).collect {|i| (a[i] + b[i]) % 10  }
end

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# File 'lib/crypto_helper.rb', line 224

def chainadd(a)
  b = a.dup
  len = a.length
  a.each_with_index{|e,i| b[i] = (e + b[(i+1) % len]) % 10 }
  b
end

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# File 'lib/crypto_helper.rb', line 235

def expand5to10(a)
  expd = chainadd(a)
  (a + expd)
end

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# File 'lib/crypto_helper.rb', line 333

def find_hole(kw, ph = 'AT ONE SIR')
  if kw.class == String then
    kwn = kw[0..(ph.length - 1)].to_numeric10
  elsif kw.class == Array
    kwn = kw.dup
  else
    raise DataError, 'Must be either String or Array of integers'
  end
  
  long  = Array.new
  short = Array.new
  i = 0
  ph.scan(/./).each do |c|
    if c == ' ' then
      long << kwn[i]
    else
      short << kwn[i]
    end
    i += 1
  end
  long.compact
end

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# File 'lib/crypto_helper.rb', line 301

def keyshuffle(key, base = BASE)
  word = (key + base).condensed.dup
  len = key.condensed.length
  height = base.length / len
  
  
  # Odd rectangle
  #
  if (base.length % len) != 0
    height = height + 1
  end
  
  res = ''
  (len - 1).downto(0) do |i|
    0.upto(height - 1) do |j|
      if word.length <= (height - 1) then
        return res + word
      else
        c = word.slice!(i * j)
        if not c.nil? then
          res = res + c.chr
        end
      end
    end
  end
  res
end

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# File 'lib/crypto_helper.rb', line 187

def normalize(a)
  a.collect!{|e| (e + 1) % 10 }
end

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# File 'lib/crypto_helper.rb', line 204

def p1_encode(p1, p2)
  r = Array.new
  p1.each do |e|
    r << p2[(e + 10) % 10 - 1]
  end
  r
end

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# File 'lib/crypto_helper.rb', line 195

def str_to_numeric(str)
  str.split('').collect{|i|  i.to_i }
end

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# File 'lib/crypto_helper.rb', line 253

def submod10(a, b)
  len = a.length
  (0..len-1).collect{|i| (a[i] - b[i] + 10) % 10 }
end