From: aaaa aaaaaaaaaaa <mk@...>
Date: 2010-08-18T07:05:49+09:00
Subject: Base64 multiple by 4

Hello,

I'm in the need of a Base64 decoding method that can decode a string
multiplied by 4. At the current moment I have the following method:


    def decode(encoded)
      if not encoded.length % 12 == 0
        raise BadInputError,
          "can only decode strings which are a multiple of 4
characters."
      end

      decoded = String.new

      k = -1
      while (k < encoded.length - 1) do
        right = 0
        left = 0

        (0..5).each do |i|
          k = k + 1
          right |= encoding_characters.index(encoded[k]) << (i * 6)
        end

        (0..5).each do |i|
          k = k + 1
          left |= encoding_characters.index(encoded[k]) << (i * 6)
        end

        (0..3).each do |i|
          decoded += ((left & (0xFF << ((3 - i) * 8))) >> ((3 - i) *
8)).chr
        end

        (0..3).each do |i|
          decoded += ((right & (0xFF << ((3 - i) * 8))) >> ((3 - i) *
8)).chr
        end
      end

      return decoded
    end

What I need (to be exact) is a ruby port of the encode/decode method
from
http://www.koders.com/java/fid2B76F86B8F8FF984EFE3C04AC6DE198E40D8EF41.aspx

Thanks in advance.
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