Module: Blur::Encryption::Base64

Defined in:
library/blur/encryption/base64.rb

Overview

The Encryption::Base64 module differs from the original Base64 implementation. I’m not sure how exactly, perhaps the charset?

I originally found the Ruby implementation of FiSH on a website where it was graciously submitted by an anonymous user, since then I’ve implemented it in a weechat script, and now I’ve refactored it for use in Blur.

See Also:

Constant Summary collapse

Charset =

The difference I suspect between the original Base64 implementation and the one used in FiSH.

"./0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

Class Method Summary collapse

Class Method Details

.decode(string) ⇒ String

Decode a base64-encoded string.

Returns:

  • (String) —

    Base64-decoded string.



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# File 'library/blur/encryption/base64.rb', line 22

def self.decode string
  unless string.length % 12 == 0
    raise BadInputError, "input has to be a multiple of 12 characters."
  end

  String.new.tap do |buffer|
    j = -1
    
    while j < string.length - 1
      right, left = 0, 0

      6.times{|i| right |= Charset.index(string[j += 1]) << (i * 6) }
      6.times{|i| left  |= Charset.index(string[j += 1]) << (i * 6) }

      4.times do |i|
        buffer << ((left & (0xFF << ((3 - i) * 8))) >> ((3 - i) * 8)).chr
      end

      4.times do |i|
        buffer << ((right & (0xFF << ((3 - i) * 8))) >> ((3 - i) * 8)).chr
      end
    end
  end
end

.encode(string) ⇒ String

Encode a string-cipher.

Returns:

  • (String) —

    Base64-encoded string.



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# File 'library/blur/encryption/base64.rb', line 50

def self.encode string
  unless string.length % 8 == 0
    raise BadInputError, "input has to be a multiple of 8 characters."
  end

  left = 0
  right = 0
  decimals = [24, 16, 8, 0]

  String.new.tap do |buffer|
    string.each_block do |block|
      4.times{|i| left  += (block[i].ord << decimals[i]) }
      4.times{|i| right += (block[i+4].ord << decimals[i]) }

      6.times{|i| buffer << Charset[right & 0x3F].chr; right = right >> 6 }
      6.times{|i| buffer << Charset[left  & 0x3F].chr; left = left >> 6 }
    end
  end
end