1.7 KiB
CHALLENGE:
rskbansal hacked into nasa mainframe and intercepted a radio signal from deep space along with a very SUS image.
He tried using data representation but soon realised that he seems to be missing something...Help him figure out the secret!!!
HINT: skbansal asked Huffman for help, he suggested to maybe try messing around with histograms.
SOLVE:
The challenge description mentions 'deep space' which hints at using DeepSound for analyzing the wav file.
On putting the secret.wav in DeepSound, we get a secret.zip file
The zip file required a password to unzip.
On using sstv on the wav file, we obtain the password of the zip file as 'mogambro'
On entering the password, the zip file gave two pkl files: enc_data.pkl and temp.pkl
The hint mentioned Huffman and histograms. Searching steganography techniques using Huffman and histograms I came across the below GitHub repo:
https://github.com/TejveerSingh13/Image-Steganography
The link contains a README file which has a youtube link along with written instructions as to how to use the attached python files that contain the actual working code for the Huffman Encoding and Compression algorithm.
On using the enc.png file and enc_data.pkl along with the decode option in the histo-shift.py code, we get a text file with a bunch of binary numbers. Now this text file and the tempo.pkl file need to be used in the huffman.py code which gives another text file that contains the decoded flag.
FLAG: bitsctf{s73g4n06r4phy_15_n07_45_345y_45_17_533m5}