Method and apparatus for providing an adaptable security level in an electronic communication

#The present invention relates to a method and apparatus for providing an adaptable security level in an electronic communication.

#In electronic communications, it is often necessary to prevent an eavesdropper from intercepting a message. It is also desirable to have an indication of the authenticity of a message, that is a verifiable identification of the sender. These goals are usually achieved through the use of cryptography. Private key cryptography requires sharing a secret key prior to initiating communications. Public key cryptography is generally preferred as it does not require such a shared secret key. Instead, each correspondent has a key pair including a private key and a public key. The public key may be provided by any convenient means, and does not need to be kept secret.

#There are many variations in cryptographic algorithms, and various parameters that determine the precise implementation. In standards for wireless communications, it has been customary to set these parameters in advance for each frame type. However, this approach limits the flexibility of the parameters.

#An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which:

#FIG. 1 is a schematic representation of a communication system;

#FIG. 2 is a schematic representation of an information frame exchanged in the communication system of FIG. 1;

#Referring to FIG. 1, a communication system 10 includes a pair of correspondents 12, 14 connected by a communication link 16. Each correspondent 12, 14 includes a respective cryptographic unit 18, 20.

#Each correspondent 12, 14 can include a processor 22, 24. Each processor may be coupled to a display and to user input devices, such as a keyboard, mouse, or other suitable devices. If the display is touch sensitive, then the display itself can be employed as the user input device. A computer readable storage medium (not shown) is coupled to each processor 22, 24 for providing instructions to the processor 22, 24 to instruct and/or configure processor 22, 24 to perform steps or algorithms related to the operation of each correspondent 12, 14, as further explained below. The computer readable medium can include hardware and/or software such as, by way of example only, magnetic disks, magnetic tape, optically readable medium such as CD ROM's, and semi-conductor memory such as PCMCIA cards. In each case, the medium may take the form of a portable item such as a small disk, floppy diskette, cassette, or it may take the form of a relatively large or immobile item such as hard disk drive, solid state memory card, or RAM provided in a support system. It should be noted that the above listed example mediums can be used either alone or in combination.

#In order to transfer data between the correspondents 12, 14, a packet stream 30 is assembled at one of the correspondents in accordance with a defined protocol. The packet stream 30 is shown schematically in FIG. 2 and is composed of one or more frames 31, each of which has a header 32 and data 34. In some protocols, the packet may itself be organised as a frame with a header 32a and the data 34a consisting of a collection of individual frames. The header 32 is made up of a string of bits and contains control information at specified locations within the bit stream.