Is concealing part of one's personal money from a father who takes the entire salary considered a sin, and is it permissible to resort to "undoing magic" - as it is called - in cases of a father's cruelty and prevention of marriage?

There is no objection to saving part of one's salary and concealing it from one's father for personal needs. The father is not permitted to take from his daughter's money except to the extent of his need, and it is not permissible for him to take her entire salary. One must be dutiful and respectful towards one's parents and endure their harshness with patience. Abusing a Muslim is فسوق (disobedience/sinfulness). The Prophet, peace and blessings be upon him, said: "The believer is not one who slanders, or curses, or is obscene, or vulgar." It is permissible to seek to break magic through legal Ruqyah. It is forbidden to go to sorcerers and astrologers.