A method of securing network authentication information at a data processing device includes determining a boot source from which to boot the device and comparing the boot source to an expected source. If the boot source is not the expected source, access to the network authentication information is inhibited, such as by disabling access to the portion of memory that stores the authentication information. Further, if the boot source is the expected source, boot code authentication information is retrieved from memory and verified during the boot sequence. If the device authentication information is not authenticated, access to the network authentication information is inhibited. Accordingly, access to the network authentication information is allowed only if the data processing device is booted from an expected source, and only if the boot code is authenticated, thereby reducing the likelihood of unauthorized access to the network authentication information.