# Secret Code
To gain access to the tomb containing the relic, you must find a way to open the door. While scanning the surrounding area for any unusual signals, you come across a device that appears to be a fusion of various alien technologies. However, the device is broken into two pieces and you are unable to see the secret code displayed on it. The device is transmitting a new character every second and you must decipher the transmitted signals in order to retrieve the code and gain entry to the tomb.
## Writeup
If we open the **RA_CA_2023_6-job.gbrjob** with **KiCad Gerber View** program, we can see the board project used to send the signal:
![board](https://github.com/MicheleMosca/CTF/raw/main/Cyber%20Apocalypse%202023/Hardware/Secret%20Code/.images/board.png)
The component on the middle of the board is a **seven segment display**.
The **datasheet** of a classic seven segment display is this:
![seven-segment](https://github.com/MicheleMosca/CTF/raw/main/Cyber%20Apocalypse%202023/Hardware/Secret%20Code/.images/seven-segment.png)
So we can use this scheme to decode the signal:
```g -> channel 3f -> channel 7a -> channel 2b -> channel 5e -> channel 6d -> channel 0c -> channel 4DP -> channel 1```
So, now we can able to decode the signal in this string:
```4854427b70307733325F63306d33355F6632306d5F77313768316E4021237d```
If we decode it from **hex**, we get the flag:
```HTB{p0w32_c0m35_f20m_w17h1n@!#}```