The Dream Book of Self-Knowledge

Key

often a phallic symbol in which a key in a keyhole symbolizes the phallus in female genitalia.
increasing or decreasing in size: clearly a phallic symbol.
to one's front door: enables the dreamer to enter earthly events and then return to inner experience.
to a gate: not a sexual symbol, but represents the conscious mind enabling the dreamer to unify one part of the consciousness with another.
to means of transportation (car, bus, train, etc.): in addition to a less frequent sexual meaning, it is more informative in meaning, i.e. whether the dreamer is or is not able to continue down the path of self-improvement.
to a cellar: a chance to descend into one's subconscious and to discover here unsuspected aspects of one's psyche.
locking with a key: conscious separation from unwanted dream images.
unlocking with a key: the conscious entrance to new dream images (the dream usually returns in this way to past experiences that are usually of an instinctual nature and erotically charged).
broken, damaged: the dreamer is unconsciously trying to enclose himself in a single level of experience and no longer want to know what he is separated from (by locking); the introvert thereby subconsciously distances himself from images of the external world, the extrovert from internal content of his own psyche.
lost: the end of a sexually motivated relationship (mere desires can also be expressed in this way) or a temporary inability to recognize other states of consciousness.
lending: a temporary interruption of a sexual relationship.
giving, relinquishing keys: abandoning a sexual (or potential sexual) relationship.
hanging on wires: individual sexual relations that have left an emotional imprint on the dreamer's consciousness (and so can depict a look back at one's entire life).
many keys: many sexual relationships (past, current or future), or often many possibilities of entering into various dream images and other levels of consciousness.
without a lock: this usually is not a phallic symbol, but "unlocks" future possibilities that can be achieved.
finding someone else's keys: the possibility for a unique sexual relationship if we also find the lock that the key fits; otherwise this is a chance to enter into other dream images (sometimes this represents a descent to the subconscious or a shift to another level of consciousness).
finding one's lost, misplaced keys: the dreamer is offered the chance to renew an erotically tinged relationship or the chance to recognize other levels of his own psyche.
in a lock: can symbolize a stable partner bond (not only the dreamer's) and also enables the dreamer to separate himself at any time from an experience, or opens one to him.
old-fashioned: enables entrance to past experiences (often to past lives).
as a weapon: you are overly concerned with sexuality and exploiting the weaknesses of your partner.
people inserting a key in the lock of the dreamer's door: the possibility of marital or partner infidelity.
of others: can often indicate relations of others around you.
guarding or having custody of a key: the body's instinctual urges are under control.
destroying: the dreamer is unconsciously trying to enclose himself in a single level of experience and no longer want to know what he is separated from (by locking); the introvert thereby subconsciously distances himself from images of the external world, the extrovert from internal content of his own psyche.
on the table: a chance to establish a sexual relationship; if we surrender this chance directly in the dream, we are elevating the dream experience at least to the emotional level.
a key as a source of ionizing radiation, radioactive keys: the dreamer is receiving the chance to willfully transform sexual desire to the emotional and later spiritual consciousness.