Re: ARG Puzzle with 3.5 BTC Private Key Prize

There's definitely some kind of file/data embedded in Space.mp4, with ffmpeg, I can do:

Code:

ffmpeg -i Space.mp4 -c:a copy -c:v copy out.mp4

and out.mp4 will be about 2.1mb smaller, even though it contains the same two streams.

Code:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Space.mp4':
  Metadata:
   major_brand : mp42
   minor_version : 0
   compatible_brands: isommp42
   creation_time : 2014-02-25 11:26:52
  Duration: 00:02:48.21, start: 0.000000, bitrate: 444 kb/s
   Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x360 [SAR 1281:1280 DAR 427:240], 244 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
   Metadata:
   handler_name : VideoHandler
   Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 95 kb/s (default)
   Metadata:
   creation_time : 2014-02-25 11:26:56
   handler_name : IsoMedia File Produced by Google, 5-11-2011

In addition, I think I found the original copy of the video file (before extra data was embedded into it):

Code:

youtube-dl --format 18 https://www.youtube.com/watch?v=3rysbn9bZ54

This file contains the same video and audio streams found in Space.mp4. If extract using ffmpeg:

Code:

ffmpeg -i Space.mp4 -c:a copy -c:v copy a.mp4
ffmpeg -i Laffe\ the\ Fox\ -\ Left\ Alone\ in\ Outer\ Space-3rysbn9bZ54.mp4 -c:a copy -c:v copy b.mp4
sha256sum a.mp4 b.mp4

I get:

Code:

37f60f1717c142e15baec5a429a0ff07ed1d6efe122a06a15a77228170ed051f a.mp4
37f60f1717c142e15baec5a429a0ff07ed1d6efe122a06a15a77228170ed051f b.mp4

So I'm pretty sure that it's the original file before extra data was embedded.

So, now the interesting part, let's check the size in bytes of Space.mp4 and the original from YouTube:

Code:

du -b Space.mp4
9356135 Space.mp4
du -b Laffe\ the\ Fox\ -\ Left\ Alone\ in\ Outer\ Space-3rysbn9bZ54.mp4
7209006 Laffe the Fox - Left Alone in Outer Space-3rysbn9bZ54.mp4

9356135-7209006 = 2147129, which is the number found in Number.txt

So, there are 2147129 bytes of additional data besides the audio and video streams in Space.mp4

Edit: extract the extra data with this:

Code:

dd bs=1 skip=7209006 if=Space.mp4 of=binary

The sha256sum of the extra data is cbd47112ad2b9f3661e6506c7999afabd0f468b3a4acec81e0618ef98cb24bf3