A method and arrangement is disclosed for providing a user, not previously having an individual subscription with a network operator, with credentials for secure access to network services. The arrangement includes a gateway, associated with a subscription for network services, having means for generating and exporting to a user entity personalized user security data derived from security data related to the subscription. In particular, the derivation of credentials is based on a function that is shared between network and gateway and further conveniently makes use of bootstrapping on keying material from the subscription authentication. Pre-registered user identities are assigned trusted users who, thereafter, can download credentials and authenticate for service access. The invention may be implemented at a public place for providing temporary visitors network access whereby trust may exemplary be established by presenting a credit card.