> For the complete documentation index, see [llms.txt](https://picoctf2021.haydenhousen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://picoctf2021.haydenhousen.com/cryptography/play-nice.md).

# Play Nice

## Problem

> Not all ancient ciphers were so bad... The flag is not in standard format. `nc mercury.picoctf.net 6057` playfair.py

* [Program](https://github.com/HHousen/PicoCTF-2021/blob/master/Cryptography/Play%20Nice/playfair.py)

## Solution

1. Look at the source code and at the bottom it links to [the Wikipedia page for a Playfair cipher](https://en.wikipedia.org/wiki/Playfair_cipher)
2. Find a Playfair cipher decoder, such as [DCode](https://www.dcode.fr/playfair-cipher). Paste in the ciphertext `y7bcvefqecwfste224508y1ufb21ld` and the alphabet/key `meiktp6yh4wxruavj9no13fb8d027c5glzsq`. Make sure to increase the grid size to 6x6 so the entire alphabet fits.
3. Click "Decrypt" to get `WD9BUKBSPDTJ7SKD3KL8D6OA3F03G0` convert this to lowercase with `python -c "print('WD9BUKBSPDTJ7SKD3KL8D6OA3F03G0'.lower())"` to get `wd9bukbspdtj7skd3kl8d6oa3f03g0`.
4. Paste the decrypted text into the program on the server to get the flag: `Congratulations! Here's the flag: 2e71b99fd3d07af3808f8dff2652ae0e`.

### Flag

`2e71b99fd3d07af3808f8dff2652ae0e`


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://picoctf2021.haydenhousen.com/cryptography/play-nice.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.