1. Computing system comprising: a token reader; a trusted device which is physically and logically protected from unauthorised modification, the trusted device having therein a device memory, and a device interface adapted for communication with the token reader; and a security token having therein a token processor and a token memory; wherein validation information is stored in the device memory and a secret is stored in the token memory, and whereby on provision of validation information from the device memory to the token memory, and satisfactory completion of a validation process by the token processor, the security token is adapted to provide the secret to the device memory.