1. A key management device for electronic memories, comprising: a keyword memory for simultaneously storing a plurality of digital keywords; a key selection device which is connected to the keyword memory; a central memory unit, which contains first memory cells for storing markers and second memory cells for storing encrypted data words; an addressing unit for addressing the first and second memory cells of the central memory unit; an encryption unit, which is connected to the second memory cells and the keyword memory; and a decryption unit, which is connected to the second memory cells and the keyword memory; wherein the key selection device generates an assignment between a digital keyword stored in the keyword memory and the data word encrypted with said keyword.