In one embodiment, a method for using credentials for a mobile node to protect the transfer of posture data is provided. A network access device receives a message from a mobile node for access to a network. The message includes posture data encrypted using credentials for the mobile node. The credentials may be found in a storage card that is used to identify the mobile node. The network access device determines decryption information for the mobile node. For example, the credentials for the mobile node may be stored in a home location register (HLR) and are retrieved. The posture data is then decrypted using the credentials. The posture data is processed in a network admission control procedure for allowing access to the network. For example, a policy for access to the network may be installed based on the posture data.