| 摘要 |
<p>The present invention relates to a method of an apparatus for encrypting and decrypting information signals to prevent the unauthorized use thereof. The signals are normally arranged as a succession of lines of active information, with each line having a line timing reference. The method of encryption comprises the steps of individually time shifting the active information portion of at least some of the lines of the signals with respect to the line timing reference by selected amounts, and providing an indication of the time shifting performed to enable subsequent decrypting. The decrypting method comprises the steps of providing an indication of the time shifting performed on a given line and restoring the original time relationship between the line timing reference and the line of information.</p> |
