System and method for distribution of identity based key material and certificate

A network node, the network node comprising:

• a key pair generation circuit,
• wherein the key pair generation circuit generates a public key and a corresponding private key,
• wherein the public key is arranged for encryption according to an asymmetric-key cryptographic scheme,
• wherein the private key is arranged for decryption according to the asymmetric-key cryptographic scheme,
• a communication circuit,
• wherein the communication circuit sends the public key to a certificate authority device,
• wherein the communication circuit receives a certificate and encrypted local key material,
• wherein the network node has an identifier that is generated by applying an identity forming function to the certificate,
• wherein the identity forming function comprises a cryptographic hash function,
• wherein the local key material is generated by applying a local key material generation algorithm of an identity-based key pre-distribution scheme on root key material and the identifier of the network node,
• a decryption circuit,
• wherein the decryption circuit decrypts the received encrypted local key material using the private key to obtain the local key material,
• a key storage,
• wherein the key storage stores the local key material and the private key, and
• a certificate storage,
• wherein the certificate storage stores the certificate;
• wherein the network node selects a nonce,
• wherein the communication circuit sends the nonce to a certificate authority device,
• wherein the communication circuit receives a certificate authority certificate and an authentication token from the certificate authority device,
• wherein the authentication token is based on the nonce and a shared key,
• wherein the shared key is based on the identifier of the network node,
• wherein the network node generates the shared key from the certificate authority certificate and local key material of the network node, and
• wherein the network node verifies the authentication token based on the generated shared key.

A certificate authority device comprising:

• a communication circuit,
• wherein the communication circuit receives a public key from a network node,
• a key storage,
• wherein the key storage stores root key material for an identity:
• based key pre-distribution scheme,
• a local key material circuit,
• wherein the local key material circuit generates local key material specific for the network node by applying a local key material generation algorithm of the identity-based key pre-distribution scheme on the root key material and an identifier of the local node,
• wherein the identifier is obtained by applying an identity forming function to a certificate of the network node,
• wherein the identity forming function comprises a cryptographic hash function, and
• an encryption circuit,
• wherein the encryption circuit encrypts at least the local key material specific for the network node by the public key of the network node,
• wherein the communication circuit sends the encrypted local key material to the network node;
• wherein the communication circuit receives a nonce from the network node,
• wherein the certificate authority device obtains a certificate authority certificate and certificate authority local key material generated for an identifier obtained from the certificate authority certificate by an identity circuit,
• wherein the certificate authority device generates a shared key from the network node identifier and the certificate authority local key material,
• wherein the certificate authority device computes an authentication token from the nonce and the shared key, and
• wherein the communication circuit of the certificate authority device sends the certificate authority certificate and authentication token to the network node for verification by the network node.

A network node method, the network node method comprising:

• generating a public key and a corresponding private key,
• wherein the public key is arranged for encryption according to an asymmetric-key cryptographic scheme,
• wherein the private key is arranged for decryption according to the asymmetric-key cryptographic scheme,
• sending the public key to a certificate authority device
• receiving a certificate and encrypted local key material,
• wherein the network node has an identifier obtainable by applying an identity forming function to the certificate,
• wherein the identity forming function comprises a cryptographic hash function,
• wherein the local key material is generated by applying a local key material generation algorithm of an identity-based key pre-distribution scheme on root key material and the first identifier,
• decrypting the received encrypted local key material using the private key to obtain the local key material,
• storing the local key material, the private key, and the certificate,
• selecting a nonce,
• sending the nonce to the certificate authority device,
• receiving a certificate authority certificate and an authentication token from the certificate authority device,
• wherein the authentication token is based on the nonce and a shared key,
• wherein the shared key is based on the identifier of the network node,
• generating the shared key from the certificate authority certificate and local key material of the network node, and
• verifying the authentication token based on the generated shared key.

A certificate authority method, the certificate authority method comprising

• receiving a public key from a network node,
• generating local key material specific for the network node by applying a local key material generation algorithm of the identity-based key pre-distribution scheme on root key material and an identifier,
• wherein the root key material is arranged for an identity:
• based key pre-distribution scheme,
• wherein the identifier is obtained by applying an identity forming function to a certificate of the network node,
• wherein the identity forming function comprises a cryptographic hash function,
• encrypting at least the local key material specific for the network node by the public key of the network node,
• sending the encrypted local key material to the network node
• receiving a nonce from the network node,
• obtaining a certificate authority certificate and certificate authority local key material generated for an identifier obtained from the certificate authority certificate by an identity circuit,
• generating a shared key from the network node identifier and the certificate authority local key material,
• computing an authentication token from the nonce and the shared key, and
• sending the certificate authority certificate and authentication token to the network node for verification by the network node.