It is also possible to decompress it using standard shell-script + gzip, if you don't have, or want to use openssl or other tools.
The trick is to prepend the gzip magic number and compress method to the actual data from zlib.compress:
printf "\x1f\x8b\x08\x00\x00\x00\x00\x00" |cat - /tmp/data |gzip -dc >/tmp/out
Edits:
@d0sboots commented: For RAW Deflate data, you need to add 2 more null bytes:
→ "\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\x00"
This Q on SO gives more information about this approach. An answer there suggests that there is also an 8 byte footer.
Users @Vitali-Kushner and @mark-bessey reported success even with truncated files, so a gzip footer does not seem strictly required.
@tobias-kienzler suggested this function for the bashrc:
zlibd() (printf "\x1f\x8b\x08\x00\x00\x00\x00\x00" | cat - "$@" | gzip -dc)
Zlib uncompression for an noob
Looks like zlib compressed data, here's more info how to deflate it: https://unix.stackexchange.com/questions/22834/how-to-uncompress-zlib-data-in-unix
More on reddit.comOpen a .bin file compressed by Zlib?
decompressing a .deflate file?
Decompress zlib in with powershell
What is ZLib compression?
What's the difference between Gzip and ZLib?
What if decompression fails?
It is also possible to decompress it using standard shell-script + gzip, if you don't have, or want to use openssl or other tools.
The trick is to prepend the gzip magic number and compress method to the actual data from zlib.compress:
printf "\x1f\x8b\x08\x00\x00\x00\x00\x00" |cat - /tmp/data |gzip -dc >/tmp/out
Edits:
@d0sboots commented: For RAW Deflate data, you need to add 2 more null bytes:
→ "\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\x00"
This Q on SO gives more information about this approach. An answer there suggests that there is also an 8 byte footer.
Users @Vitali-Kushner and @mark-bessey reported success even with truncated files, so a gzip footer does not seem strictly required.
@tobias-kienzler suggested this function for the bashrc:
zlibd() (printf "\x1f\x8b\x08\x00\x00\x00\x00\x00" | cat - "$@" | gzip -dc)
zlib-flate -uncompress < IN_FILE > OUT_FILE
I tried this and it worked for me.
zlib-flate can be found in package qpdf (in Debian Squeeze, Fedora 23, and brew on MacOS according to comments in other answers)
(Thanks to user @tino who provided this as a comment below the OpenSSL answer. Made into propper answer for easy access.)
i was playing ctf challenges and i stuck in this point can someone explain to me(this compression) and how i can uncompress this file .
$ file out.zlib out.zlib: zlib compressed data