Trusted ring

A method for generating an authentication key at a device, possibly for providing a digital signature, permits authentication of an output from a ring of peers (e.g. IoT devices). It comprises generating a respective security credential for each peer, at least one credential being generated based on at least one feature of the peer device. ICMetrics (Integrated Circuit Metrics) techniques may be used to generate the credentials, wherein feature values related to network configuration, device connectivity or contacts are inputted to a key generation algorithm to produce public/private keys Pr, Pb. A ring key is generated, possibly depending on peer security credentials, and the authentication key is generated in dependence on the ring key, a security credential of a first peer and respective security credentials of at least one other peer. A tolerance value may indicate the number of peers required to process the ring key, and the ring key may be a function of a polynomial of an order one less than the tolerance value. The authentication key may be generated by generating a verification function and XORing it with the ring key. This method may be used for committing a transaction on a permissioned blockchain.