# 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.
![Alt text](https://github.com/uac-ctf/MetaRed2021-5th-Writeups/blob/master/hardware/credits/pv1.png?raw=true)
Zooming in into each event would reveal a structure composed by an initial set of transactions, and then two chunks of data.
![Alt text](https://github.com/uac-ctf/MetaRed2021-5th-Writeups/blob/master/hardware/credits/pv2.png?raw=true)
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}