ucnv · August 13, 2009 09:26
diff --git a/jpeg_sos_breaker.rb b/jpeg_sos_breaker.rb
 #!/usr/bin/env ruby
 # Test script for yet another JPEG glitch technique.
 # Rewriting YCbCr Huffman table selectors in the JPEG header.
 require 'erb'

 data = File.open(ARGV.first) {|f| f.read }
 sos = data.index "\xFF\xDA"
 ns = data[sos + 4]
 files = (4 ** ns).times.collect do |i|
  sign = "%0#{2*ns}b" % i
  ns.times do |j|
    flag1 = (sign[j * 2] == 49) ? 0x10 : 0
    flag2 = (sign[j * 2 + 1] == 49) ? 1 : 0
    data[sos + 6 + j * 2] = flag1 | flag2
  end
  file = sign + '.jpg'
  File.open(file, 'w') do |f|
    f.print data
  end
  file
 end

 file = 'index.html'
 File.open(file, 'w') do |f|
  f.print ERB.new(DATA.read).result(binding)
 end

 `open #{file}`

 __END__
 <html>
 <head><title>Rewrite SOS Glitch</title></head>
 <body>
 <% files.each do |i| %>
  <img alt="<%= i %>" src="<%= i %>">
 <% end %>
 </body>
 </html>
	#!/usr/bin/env ruby
	# Test script for yet another JPEG glitch technique.
	# Rewriting YCbCr Huffman table selectors in the JPEG header.
	require 'erb'

	data = File.open(ARGV.first) {\|f\| f.read }
	sos = data.index "\xFF\xDA"
	ns = data[sos + 4]
	files = (4 ** ns).times.collect do \|i\|
	sign = "%0#{2*ns}b" % i
	ns.times do \|j\|
	flag1 = (sign[j * 2] == 49) ? 0x10 : 0
	flag2 = (sign[j * 2 + 1] == 49) ? 1 : 0
	data[sos + 6 + j * 2] = flag1 \| flag2
	end
	file = sign + '.jpg'
	File.open(file, 'w') do \|f\|
	f.print data
	end
	file
	end

	file = 'index.html'
	File.open(file, 'w') do \|f\|
	f.print ERB.new(DATA.read).result(binding)
	end

	`open #{file}`

	__END__
	<html>
	<head><title>Rewrite SOS Glitch</title></head>
	<body>
	<% files.each do \|i\| %>
	<img alt="<%= i %>" src="<%= i %>">
	<% end %>
	</body>
	</html>