# data structure of random / compressed data

can anybody explain to me what data structure results after data is compressed? I just try to find out the difference between random data and compressed data, the entropy of both is very high while the distribution seems to be different (e.g. when I use chi-square-test).

i hope somebody can help me and thanks in advance! tom

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You'll need to specify a specific compression algorithm. –  CodesInChaos Aug 18 '12 at 13:54
any compression algorithm, e.g. huffman –  tom Aug 18 '12 at 16:03
There is no algorithm that can detect any kind of compressed data. It's only possible to detect specific compressed file formats. –  CodesInChaos Aug 18 '12 at 16:11
the program "ent" can do using the chi-square test (fourmilab.ch/random). I tried this test and it is possible to distinguish between compressed and random data, I just want to know how this is possible. –  tom Aug 18 '12 at 17:15
i didnt take any specific file type but data from /dev/urandom –  tom Aug 18 '12 at 17:19