There's an authorization code for some Thyrin Labs information here, along with someone's favorite song. But it's been encrypted! Find the authorization code.
encrypted.txt[1]

hint:You may want to look at what the relative frequencies of letters in english text are.
[1]https://picoctf.com/api/autogen/serve/encrypted.txt?static=false&pid=0cffe6fd67e39c91501cb9d843984cb2