Linguist

Linguist
Feat

You have studied languages and codes, gaining the following benefits:
- You learn three languages of your choice.
- You can ably create written ciphers. Others can't decipher a code you create unless you teach them, they succeed on an Intelligence check (DC equal to your Intelligence score + your proficiency bonus), or they use magic to decipher it.

Source: Player's Handbook (2014) (PHB), page 167