A method and system for authenticating messages received from users across multiple remote devices are provided. A residential gateway authenticates a user using a modified digest authentication scheme by storing a sequence number in the nonce field. Access encryption keys and sequence number spaces may be assigned based on user or on user/remote device pairs. When sequence number spaces are assigned based on user, and the user uses multiple remote devices to access the residential gateway, the sequence number space may be divided into mini-sequence number spaces for each of the multiple remote devices. Access encryption may be two-tiered, such that a secondary key is generated based on a user's primary key, and the secondary key is only valid for a limited amount of time before it expires and a new secondary key must be generated.