For communicating securely between electronic devices using symmetric key encryption, a first electronic device transfers to a second electronic device metadata with positional information which indicates the position of a first cryptographic key in a cryptographic key hierarchy. The second electronic device derives the first cryptographic key by way of a one-way function from a second cryptographic key stored in the second electronic device, using the positional information received from the first electronic device. Subsequently, the first electronic device and the second electronic device communicate data securely with symmetric key encryption using the first cryptographic key.