St. Jude Parish-Londonderry, NH issued the following announcement on Aug. 23

Keys hold great significance for those who carry them. They represent the trust and authority of the owner when given to another person. We may give our house key to a trusted friend to take care of our matters while we are away. We may give keys to someone responsible for maintaining or working in a particular building.

Keys to vehicles are given to people who have proven themselves responsible drivers. The readings today focus on this kind of trust—the trust that conveys authority and responsibility. In the first reading, the symbol is specifically that of a key; but the second reading and the Gospel also speak of trust and leadership as they refer to the earthly church that Jesus established.

Original source can be found here.