PDKF is a key derivation function

do not use the word "encryption", as it is actually closer to "hashing" anyways.

docs/internals.rst

@@ -260,7 +260,7 @@ Key files
 When initialized with the ``init -e keyfile`` command, |project_name|
 needs an associated file in ``$HOME/.attic/keys`` to read and write
 the repository. The format is based on msgpack_, base64 encoding and
-PBKDF2_ SHA256 encryption, which is then encoded again in a msgpack_.
+PBKDF2_ SHA256 hashing, which is then encoded again in a msgpack_.
 
 The internal data structure is as follows: