Abstract: A method carried out by a first device includes initiating an authentication session for authenticating a user of the first device with N second devices and with a third device, obtaining an asymmetric key pair comprising a public key and a private key, obtaining an identifier for the authentication session from the third device, transmitting the identifier and the public key to the second devices, receiving first data from the user and carrying out user authentication with the third device based on the first data, obtaining a respective challenge from each of the second devices, for each challenge, signing the challenge with the private key and sending the signed challenge to the respective second device the challenge was received from, receiving a message indicative of successful user authentication from each second device.