I want to play! 

So, if you take the letter "a", and replace it with the 13th letter after it, you've just encrypted the letter "a" with ROT13.

If you get to "z" before getting to the thirteenth letter, continuine counting with a, b, etc until you get to the thirteenth letter.

Now I've provided you with a cryptology tool. So did the Romans.

Enjoy!

nostr:nevent1qqsd22dc4kfvhpmtwc4su6uv0shmra062fw7hlkpkqrxsapxl4cs39spz9mhxue69uhkummnw3ezuamfdejj7q3qq8w7u2ymrghfpp6v5dpg57jpgaj2djk340a2npwzq8n64ksk6wxqxpqqqqqqzqz50gy