| 摘要 |
<p>The invention comprises a pseudo random number generator employed to create and encryption key stream. Multiple known key sequences are loaded into memories 304A-D. Segments of each of these sequences are read out in a non linear order and then combined in order to create the key stream. In the embodiments the invention reads multiple segments from a random number loaded into a further memory 302. These segments may step through the random number by differing amounts for each key sequence. The reading points may be calculated using a time dependent formula. The random number segments read out are then used to address the key sequences and the segments of the key sequences read out are combined (e.g. by XOR operations) to produce the output pseudorandom key stream. This can then be combined with the plain text (e.g. in another XOR operation).</p> |
