Encryption with password in the code

Question

I want to encrypt a file without being asked for a password, by specifying the password in the code.

I tried

(setq my-context (epg-make-context))
(epg-context-set-passphrase-callback
 my-context (lambda (&rest _ignore) "my-password"))
(epg-encrypt-file my-context "file.txt" nil "file.bin")

and I was still asked for a password.

PS. Please do not tell me that this is not secure (I know) and that I should use gnupg-agent (I already do).

Answer 1

Here is what I ended up using:

(defun sds-password ()
  "Return a consistent password for 'sds-encrypt' & 'sds-decrypt'.
Should not be a variable for security reasons."
  (concat "pass:" (auth-source-pick-first-password :host "whatever")))
(defun sds-encrypt (fname encrypted)
  "Encrypt FNAME into ENCRYPTED, cf 'sds-decrypt'."
  (call-process "openssl" nil nil nil "enc" "-pass" (sds-password)
                "-aes-256-cbc" "-salt" "-in" fname "-out" encrypted)
  (set-file-times encrypted (file-attribute-modification-time (file-attributes fname))))
(defun sds-decrypt (fname encrypted)
  "Decrypt ENCRYPTED into FNAME, cf 'sds-encrypt'."
  (call-process "openssl" nil nil nil "enc" "-d" "-pass" (sds-password)
                "-aes-256-cbc" "-salt" "-in" encrypted "-out" fname)
  (set-file-times fname (file-attribute-modification-time (file-attributes encrypted))))

This is not exactly what I asked for, but good enough for me for now.