| 摘要 |
A device for creating ciphertext from plaintext comprises: (a) receiving means for receiving a plaintext data stream; (b) storing means for, storing data representative of an Oommen-Rueda Tree (figure 1); (c) processing means for processing the plaintext data stream on a character by character basis, and for repeatedly traversing the stored Oommen-Rueda Tree for each character of plaintext to be processed, each such traversal being between the root and that leaf corresponding to that symbol of plaintext then being processed; (d) recording means for recording the Assignment Values of the branches of the Oommen-Rueda Tree traversed during the processing of the plaintext data stream. The receiving means, the storing means and the recording means are in communication with the processing means. A device for decoding ciphertext comprises: (a) receiving means for receiving a ciphertext data stream; (b) storing means for storing data representative of the Oommen-Rueda Tree utilized by the Encoder; (c) processing means for i) processing the ciphertext data stream on a character by character basis; for ii) repeatedly traversing the stored Oommen-Rueda Tree between the root and leaves of the Oommen-Rueda Tree, the choice of branch to traverse being determined by the comparison of the character of ciphertext then being processed and the Assignment Value of such branch; for iii) selecting the next character of ciphertext for processing to determine the next branch to be traversed, until a leaf is reached, whereupon the plaintext character associated with the leaf is recorded, and the processing continues from the root; and for iv) repeating the above steps (i),(ii) and (iii) until all ciphertext to be processed has been processed; (d) recording means for recording the plaintext associated with each of the leaves reached during processing. The receiving means, the storing means and the recording means are in communication with the processing means. |
