Warden of the Keys

From Tolkien Gateway

Warden of the Keys was a high office of Minas Tirith in Gondor.

At the time of the War of the Ring, the position was filled by Húrin the Tall, who gained the epithet "of the Keys". At the coronation of Aragorn, he opened a barricade (laid in place of the destroyed gate) at the gatehouse of Minas Tirith for the new king. Other than that, what other tasks and responsibilities belonged to this office remains unknown.[1]