A method and apparatus which permits access, by intermediate nodes between source and destination nodes, to selected information such as transport level information, normally included in a payload of a packet upon which encrypting security processing has been performed according to an encrypting security protocol. In the present invention, prior to performing encrypting security processing on the packet, according to the security protocol, information related to selected information normally included in a payload of the packet is stored in a field in the header of the packet where the field is not subject to the encrypting security processing. Thereafter, encrypting security processing according to the security protocol is performed on the packet. The packet including the header having stored therein information corresponding to the selected information normally included in the payload and the payload upon which encrypting security processing has been performed is then transmitted on the packet switched network to its destination. Since the information related to the selected information normally included in the payload of the packet is stored in the header of the packet, access to the selected information by the intermediate nodes between source and destination nodes in a packet switched network is possible.