Access key for a field device

A method for unlocking a field device of automation technology using an access key, comprising:

• 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 of the access key;
• ascertaining the identification feature of the field device for which the access key is to be provided;
• generating the access key such that it includes at least one hash value formed at least from the individual key read-out from the database using the ascertained identification feature, wherein the access key controls accessing the field device including parameters of the field device;
• inputting the access key to the field device;
• calculating in the field device a comparison hash value based on an individual key stored in the field device;
• comparing the comparison hash value with the access key hash value;
• and
• enabling or performing at least one function of the field device when the comparison hash value agrees with the access key hash value.

A system of automation technology, comprising:

• a plurality of field devices, each field device including an internal memory in which an individual key is stored and further including a computing unit configured to:
• receive an access key including at least one hash value;
• control access to the field device based upon an access key;
• calculate a comparison hash value based on the individual key;
• compare the hash value of the access key with the comparison hash value;
• and
• enable or perform at least one function of the field device when the comparison hash value agrees with the hash value of the input access key;
• a database of a field device manufacturer in which the individual keys are stored together with, in each case, an identification feature of the field device;
• and
• receive, by an access key generating unit, an individual key and an identification feature for a field device;
• receive, by the access key generating unit, a bitmask or a representative for the bitmask;
• calculate, by the access key generating unit, a hash value formed at least from the field device's individual key, the field device's identification feature, an offset value, and the bitmask or the representative for the bitmask;
• generate, by the access key generating unit, an access key for the field device, wherein the access key includes the hash value;
• and
• provide, from the access key generating unit, the access key for the field device.