Abstract: A lock for securing a portable device is disclosed. The lock can be inserted into a cavity. The cavity has a first sidewall and a second sidewall both of which extend away from an opening into the cavity with a gradually increasing distance between the two sidewalls for a section of the two sidewalls. The lock for securing a portable device comprises a lock body; a first engaging member projecting from the lock body and having an outside part outside the lock body, a cross-sectional area of the outside part of the first engaging member being substantially the same or become larger from a front end towards a rear end of the outside part of the first engaging member; and a second engaging member, connected to the lock body and configured to move along a side of or across the first engaging member to insert into the cavity for a locking status and to withdraw from the cavity for an unlocking status.