This challenge is called The Spetral Image b6414. From the title, we assume that Base64 and ROT14 might be involved.
When downloading the provided file, we get a .jpg file. But after analyzing it, we realize that it's not actually an image — it's an audio file disguised as a JPEG.
not a jpg file
After converting it to .wav, we end up with a 1:50 minute audio file. Given the challenge's theme, it feels like a transmission of some kind.
A bit of research shows that 1 minute and 50 seconds is exactly the duration of a Scottie DX SSTV transmission — a slow-scan TV format.
Decoding the SSTV
Using the RX-SSTV tool and playing the .wav file, we’re able to decode the SSTV signal into an image.
Note: To do this, we need to make sure our system audio is routed properly. That means enabling Stereo Mix or using a virtual audio driver like VB-CABLE. Other loopback tools can work as well.
The output from RX-SSTV gives us a encoded string.
encoded with b64 and rot14
Decoding the Final String
Given the challenge title contains b6414, we try decoding the output using Base64, and then applying a ROT14 cipher to the result.
