The message that was found in the letter has been given 964lCv5sFqsdip50KeyCkg== where it has been encrypted by a block cipher symmetric-key algorithm that has a key length size of 56 bits. The cipher that has a 56 bits is DES (Data Encryption Standard)

The clue for what the key is actually in the statement which is treasure.

Use any type DES decoder online to decode the message
<img width="600" alt="image" src="https://github.com/lenebread/GiTxHextech-Challenge-Repo/assets/166520861/19eb69d6-bcd9-4e03-9bcc-6e02740cf009">

The flag is CH3CK_CH3ST
