Abstract: A method for key generation is arranged in a client processor device, by means of which a second public client key Pc? of the client is generated. The public key Pc? is formed by a calculation, or sequence of calculations, which does not contain any operation whose result depends exclusively on the nonce s and at least one public value, or the public key Pc? being formed by a calculation, or sequence of calculations, where into each operation in which the nonce s enters, at least one non-public value enters the first private client key kc or the second private client key kc?, for example as a result of the calculation Pc?=(kc?·s)·G+(kc?·kc)·Pt.