That's nothing. How about an infinite zip file :)<p><a href="http://research.swtch.com/zip" rel="nofollow">http://research.swtch.com/zip</a>
Here are some other compression oddities: <a href="http://www.maximumcompression.com/compression_fun.php" rel="nofollow">http://www.maximumcompression.com/compression_fun.php</a><p>A 42 byte file that expands to 5 MB; a file that compresses in one compression software but not another; a file that compresses to itself; and some extreme compression software.
10 years ago most virus scanners were vulnerable to it.<p>actually you can build your own collection of files with cat /dev/zero >foo.txt ... then zip all those into a final collection of zip's -> n-levels deep ... resulting individual zip files will be tiny, but once extracted the file eats massive space (idea is to fill disk on scanning server up and create I/O errors or keep the server busy with a DOS). Also servers usually limit now the depth they are willing to scan in a zip to avoid this type of attack (workaround: only use up to 4 levels ...)
Here's an information-theory question: would there be a way to estimate the size of the decompressed output, just given the raw zip data and no size metadata, without attempting to extract it (i.e. without spending time or space proportional to the compression factor)?
Gmail won't allow you to send this file to anyone, throws an error pointing you to <a href="https://support.google.com/mail/answer/6590" rel="nofollow">https://support.google.com/mail/answer/6590</a><p>Ah, I almost forgot we are not spied on. Tried via local email client.
All files at the same "level" are identical. The 4GB file contains zeros only. I think these "data" could be compressed into even smaller size using some different methods.
There's this old discussion about zip bombs:
<a href="https://news.ycombinator.com/item?id=4616081" rel="nofollow">https://news.ycombinator.com/item?id=4616081</a>
A certain Caspian Maclean published a gzip quine on the Web in 2004, but I cannot seem to find it.
It's funny, first got to know about this a few days ago when I came across this [1, 2] interesting thread on Quora.<p>[1] <a href="http://qr.ae/sQnm5" rel="nofollow">http://qr.ae/sQnm5</a><p>[2] What is the most compressed file ever?
I'm sorry, but I have to say this: I like how this entry had 42 comments before this one: <a href="http://i.imgur.com/KmCodSM.png" rel="nofollow">http://i.imgur.com/KmCodSM.png</a>