Compressor

Compressor

Misc - 25 points

Challenge

I want to make my text file very very small! So, I did what any sane person would do and shoved it into my compressor and ran it 10 times!

Creator - @exetr

level0_564546f2b66ff26cc3b94f352aaeead5.rar

Solution

For this challenge, we are faced with 10 levels of differing archive files. Some dependencies were installed along the way

For Mac: brew install unzip unrar lzip rzip lzop p7zip

$ unrar e level0_564546f2b66ff26cc3b94f352aaeead5.rar

$ file level1
level1: Zip archive data, at least v1.0 to extract
$ unzip level1

$ file level2
level2: gzip compressed data, was "level3", from Unix, last modified: Thu Sep 28 20:30:44 2017
$ gzip --decompress level2 --suffix '' --name --keep

$ file level3
level3: POSIX tar archive (GNU)
$ tar xfk level3

$ file level4
level4: bzip2 compressed data, block size = 900k
$ bzcat -k level4 > level5

$ file level5
level5: lzip compressed data, version: 1
$ lzip -d -k level5
$ mv level5.out level6

$ file level6
level6: xz compressed data
$ mv level6 level6.xz
$ xz -d -k level6.xz
$ mv level6 level7

$ file level7
level7: rzip compressed data - version 2.1 (2228 bytes)
$ rzip -d -S '' -o level8 level7

$ file level8
level8: lzop compressed data - version 1.030, LZO1X-1, os: Unix
$ mv level8 level8.lzop
$ lzop -d level8.lzop -o level9

$ file level9
level9: ISO 9660 CD-ROM filesystem data 'CDROM
$ 7z x level9

$ file LEVEL10 
LEVEL10: ASCII text, with very long lines, with no line terminators

From here we see LEVEL10 is a base64 encoded file, and level11 is a binary encoded string.

$ cat LEVEL10 | base64 --decode > level11
$ cat level11 | perl -lpe '$_=pack"B*",$_' > level12
$ cat level12
GCTF{m4ny_m4ny_l4y3r5_0f_c0mpr3ssi0n}

Flag

GCTF{m4ny_m4ny_l4y3r5_0f_c0mpr3ssi0n}