METHOD AND APPARATUS FOR RANDOM ACCESSIBLE ENCRYPTION AND DECRYPTION BY USING A HIERARCHICAL TREE STRUCTURE OF STREAM CIPHER MODULE

摘要

PURPOSE: An apparatus for random accessible encryption and decryption by using a hierarchical tree structure of a stream cipher module and a method thereof are provided to improve the computation speed by comparing with the block cipher scheme. CONSTITUTION: A mapping unit(730) receives plain text stream, and maps the location of a specific bit and the location of the encoded bit. A random number generator(720) outputs random number sequence used for the encoding of the specific bit according to the location of the specific bit to a calculation unit(740). The calculation unit receives the plain text stream and random number sequence, and performs an exclusive OR operation.