Rating:
# Credits
**Author:** rackham
**Category:** hardware
**Difficulty:** medium
## Description
```
We would like to _Display_ credit to all the UA Cyber Sec Team. Enjoy the CTF, Merry Christmas and take our modern paper card.
```
## Solve
A file named data.sr was provided, which could be open with `Pulseview`. The file is actually a `ZIP` and a `metadata` file would hint towards `sigrok`.
Opening the file with `pulseview` would result in a reasonable number of events across multiple pins.
Zooming in into each event would reveal a structure composed by an initial set of transactions, and then two chunks of data.
The description pointed towards a Display as the word was bold. This pattern is consistent with filling a frame buffer for a display.
Channel 6 also looks like a clock, while D5 looks like data. Spinning an SPI decoder to these channels would allow obtaining a stream of bits. These bits could correspond to RGB values in a color display, or direct values for a monochrome display. This was actually the case.
A proper solve would involve parsing the SPI messages. A quicker solve would imply creating an image with `PIL`. An even quicker solve would involve a oneliner.
If we saved one of the large chunks to a file named `buffer.txt`, by exporting the annotations of the D5 channel, we could use the following:
```cat buffer.txt |cut -d ' ' -f 5 |tr -d '\n' |tr -d '\r' |sed -e "s/.\{104\}/&\n/g" -e "s/1/ /g"```
The result would be:
```
000000
0000000000
0000 0000
00 00
000 000
00 00
00 00
00 00
000 000
000 000
0000 0000
00 00
00
00
00
00
00
00000000000000
00000000000000
00
00
00
00
00000000000000
00000000000000
00 00
00 00
00 00
00 00
00 00
00 00
00 00
00
000000000
000000000000
0000000000000
000
000
00
00
000
0000
0000000000000
00000000000
0
0000
000000
0000000
00000000
00 0000000
00 0000
00 000000
00000000
0000000
000000
0000
0
000
0000000 0000000
00000000 0000000
00 00
00 00
00 0
000 000
000 0000
00 000
00 00 00
00 00 00
000 000 000
000000000000
000000 0000
00
00000000000000
00000000000000
00 00
00 00
00 00
00 000
00000000
000000
0000
00
000
00000
000000
00 000
00 0000
00 000
00000000000000
00000000000000
00
00
00000000000000
00000000000000
00000000000000
00 000
00 00
00 00
000 00
0000000000
00000000
0000
00 0
000 000
000 0000
00 000
00 00 00
00 00 00
000 000 000
000000000000
000000 0000
00
0000000000
0000000000
0000000000
00
00
00
00
00
00
00
00
00
00
00
00
0
00000
00000000
0000000
0000
0000000
000000
00000
0000000
00000
000000
00000000
000000
00
00
00
00
00
00
00
00
00
000 00
0000 0000000
000 0000000
000 000 00
00 00 00
00 00 00
000 000 00
00000000 00
000000 00
0000
00000000000000
00000000000000
00 00
00 00
00 00
00 000
00000000
000000
0000
00
00
00
0000000000000
00000000000000
00000000000000
00 00
0000000 0000000
0000000 0000000
```
## Flag
CTFUA{3P4p3r_w_5P1}
