From: Jim Cain <jecain@...>
Date: 2008-09-05T09:38:53+09:00
Subject: Re: Arcfour encryption algorithm

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I've been using this implementation for a while. Unfortunately, the
file doesn't have any author info in it, and I can't find it in Google
any longer, so I'm not sure who deserves credit for it.

I also make this patch to it:

class ARC4

  def setup(key)
    #@init_s = Array.new(256) { |i| i }
    @init_s = ''
    0.upto(255) { |i| @init_s << i }
    j = 0
    for i in 0 .. 255
      j = (j + @init_s[i] + key[i % key.size]) & 0xff
      @init_s[i], @init_s[j] = @init_s[j], @init_s[i]
    end
    reset
  end

  def reset
    @s = @init_s.dup
    @i = 0
    @j = 0
  end

end

Cheers,
Jim

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