Access key for a field device

A method for providing an access key for a field device of automation technology, wherein the access key controls accessing of the field device, includes: producing an individual key; storing the individual key in a database together with an identification feature of the field device; storing the individual key in the field device which is to be unlocked based on an input access key; ascertaining at least the identification feature of the field device for which the access key is to be provided; and forming/producing/generating the access key, such that it includes at least one hash value, wherein the hash value is formed at least from the individual key read-out from the database with the assistance of the ascertained identification feature.