rgbCTF-2020

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14 July 2020

vaporwave2

by INXS_JOY

I got two versions. I got twooo versions…

Files

Solution

This ones a bit tricky if you haven’t processed tracks before.

We are given two audio file and upon downloading its pretty evident that they are the same tracks. Whenever we have identical objects we try to find the difference. So basically a diff needs to be performed on the two tracks. Song diff is performed in the following way:

1.Invert one of the track
2.Merge the inverted track and the other track
3.If a completely 0db audio is produced then both the tracks are identical , else the produced output is the difference of the tracks.

I generally prefer using Audacity but you can use any audio editor. The following steps are Audacity specific.

1. Import both the tracks into Audacity.
2. Select one of the tracks and go to Effects->Invert
3. Now select both of the tracks and Choose Tracks->Mix->Mix and Render.
4. Export the resulting audio and feed into a Spectogram analyzer.

I used this site to create spectograms:https://convert.ing-now.com/audio-spectrogram-creator/ And the spectogram for the inverted and merged audio produces this:

alt text

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rgbCTF{s3v3r3_1nv3r71g0}
tags: ZTC