Privacy preserving authentication and key agreement protocol for apparatus-to-apparatus communication

A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the following:

• obtaining a first identifier associated with the apparatus, wherein the first identifier is different from a second identifier associated with the apparatus;
• providing one or more messages to at least one further apparatus of a set of one or more apparatuses, wherein at least one of the one or more messages comprises key information of the apparatus and is associated with the first identifier associated with the apparatus;
• and
• determining a session key of a communication session associated with the apparatus and at least one further apparatus, based on one or more messages received from at least one further apparatus of the set of one or more apparatuses, wherein at least one of the messages comprises key information of the respective further apparatus and is associated with a first identifier associated with the respective further apparatus
• wherein the apparatus is associated with a public key and the public key can be determined based on the first identifier associated with the apparatus and a first hash function,
• wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform at least one message of the one or more messages provided to at least one further apparatus of the set of one or more apparatuses:
• determining a hash value based on the respective message and a second hash function;
• determining a signature based on the hash value, the public key and a private key associated with the apparatus;
• and
• providing the signature to the further apparatus associated with the respective message.

An apparatus comprising:

• at least one processor;
• and
• at least one memory including computer program code;
• the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:
• obtaining a first identifier associated with the apparatus, wherein the first identifier is different from a second identifier associated with the apparatus;
• providing one or more messages to at least one further apparatus of a set of one or more apparatuses, wherein at least of the one or more messages comprises key information of the apparatus and is associated with the first identifier associated with the apparatus;
• and
• determining a session key of a communication session associated with the apparatus and at least one further apparatus, based on one or more messages received from at least one further apparatus of the set of one or more apparatuses, wherein at least one of the messages comprises key information of the respective further apparatus and is associated with a first identifier associated with the respective further apparatus,
• wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform verifying at least one message of the one or more received message,
• wherein said verifying comprises:
• determining a hash value based on the respective message and a second hash function;
• and
• verifying the respective message based on a signature associated with the message and based on the hash value and a public key associated with the further apparatus associated with the message;
• wherein the public key can be determined based on the first identifier associated with the apparatus and a first hash function.

An apparatus comprising:

• at least one processor;
• and
• at least one memory including computer program code;
• the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:
• obtaining a first identifier associated with the apparatus, wherein the first identifier is different from a second identifier associated with the apparatus;
• providing one or more messages to at least one further apparatus of a set of one or more apparatuses, wherein at least of the one or more messages comprises key information of the apparatus and is associated with the first identifier associated with the apparatus;
• and
• determining a session key of a communication session associated with the apparatus and at least one further apparatus, based on one or more messages received from at least one further apparatus of the set of one or more apparatuses, wherein at least one of the messages comprises key information of the respective further apparatus and is associated with a first identifier associated with the respective further apparatus,
• wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform:
• communicating securely with one or more apparatuses of the at least one further apparatus during the communication session based on the determined session key, wherein the apparatus and the at least one further apparatus represent a group associated with the communication session;
• and revoking the group based on at least one of an expiration date associated with the session key of the communication session, and/or a change of membership in the group, wherein said revoking the group comprises determining a new session key;
• if the expiration date associated with the session key is expired and there are changes of the membership in the group:
• providing one or more messages to at least one further apparatus of the set of one or more apparatuses, wherein at least one of the one or more messages comprises key information of the apparatus and is associated with the first identifier associated with the apparatus;
• and
• determining the new session key of the communication session associated with the apparatus and the at least one further apparatus, based on one or messages received from at least one further apparatus of the set of one or more apparatuses, wherein at least one of the one or more messages comprises key information of the respective further apparatus and is associated with a first identifier associated with the respective further apparatus, wherein the apparatus and the at least one further apparatus are members of the group after the membership in the group has changed.