Short answer: No

Long answer: Let's delve into the cryptographic stuff behind UNIX passwords, GPG, and JtC.
UNIX authentication systems never save the passwords themselves in any form, not even encrypted, but instead use a hash of the password. A hash is similar to a compression function. It takes an array of bytes (say, the letters of a password) and mangles them into a fixed length array. The idea is that a small change in the original text yields a big change in the hash, and that by hashing 2 identical texts you get the same hash. If a user wants to authenticate, the password entered is hashed, and the hash is compared to the one saved.
Since hashing means you loose information, hashes will never be collision free. To prevent 2 users accidentally having the same password hash, salts were introduced. Those are random bits prepended to the password, so that even if two users has the same password, their hashes wouldn't match up.
The biggest difference between hashing and encryption functions is that hashes are very fast.

Encryption, OTOH, takes the input message (your text file) and a key (created from your password), and sends both through an encryption function like AES. Contrary to hashes, the result usually isn't shorter than the original, but it's getting transformed, and it's recoverable while hashes are not. Also, encryption schemes usually are very resilient against attacks. For example, with AES it's still impossible to recover the key in a know-plaintext attack (meaning: you have both the original text and the encrypted text, and it's still impossible to find out the key/password used as to decrypt other messages).

John the Ripper (JtR) uses the speed of hashes to its advantage. A dictionary attack is very fast, even against salted password hashes, and even faster again NTLM passwords. But it can only attack hashes, since they're pretty fixed in their parameters, while for encryption there are a lot of variables, such as key length, algorithm used, and which block mode is being used (CBC/CFB/CTR/...)