lock: use openssl instead of gpg

bin/lock

@@ -9,11 +9,7 @@ error() {
 [ -n "$1" ] || error "input file missing"
 [ -r "$1" ] || error "can't read input file"
 
-# shellcheck disable=SC2016 # I don't want $(tty) to be expanded
 printf '#!/bin/sh
-GPG_TTY=$(tty)
-export GPG_TTY
-base64 -d <<EOF | gpg -d
+openssl enc -d -aes256 -pbkdf2 -base64 <<EOF
 %s
-EOF
-'   "$(gpg -c --cipher-algo AES256 -o - -- "$1" | base64)"
+EOF' "$(openssl enc -aes256 -pbkdf2 -base64 -in "$1")"