A typical password is about 8 characters long (and so can be stored in 8 bytes, or 64 bits). However, a typical key for encryption/decryption is much longer, and a key of 64 bits would not be considered secure. Explain this in terms of the difference between the way a secret is used as a password, and the way it is used as a key.
Hint: what happens if an attacker takes a few months to discover the secret?