Digital message encryption and authentication - 2002

A method and system for performing digital message encryption and signature encoding for use in, for example, communications and digital information storage systems. For secure communication of digital messages it is neccessary to both encrypt the message and the sign the message with a digital signature scheme to allow for authentification by the receiver. In order to the computational efficiency and reduce communications overhead in secure communications, a method and system, referred to as "signcryption", are provided in which the process of encyption and authentification are combined. The principles of public key cryptography are utilised, although any suitable keyed encryption algorithm can be employed for the message encoding. Examples of signcryption include the ElGamal, Schnorr and Digital Signature Standard. Messages to multiple separate recipients can be efficiently dealt with, and because of the low computational and communications overheads the signcryption method is particularly applicable for use in smart cards and for highly secure and authenticated key transport over ATM.