| 摘要 |
A method and apparatus processes a video image signal to generate one or more random number generator seeds. Preferably, the video image signal represents a scene that is both unpredictable and "live". As a result, potential interceptors of signals encrypted with a random number sequence derived from the seed will find it difficult, if not impossible, to determine the random number sequence. To further obscure the random number sequence from potential interceptors, a seed derived by processing a first video image signal is determined and is stored. Then, a second video image signal is received and a third video image signal is received. A difference is determined between the third video image signal and the second video image signal. If the difference exceeds a threshold (indicating that the scene represented by the video image signals is "live"), then the third video image signal is processed to generate a seed. Alternately, if the difference does not exceed the threshold, then a random number generator seed derived by processing the third video image signal may be more easily determined by an interceptor. In this instance, a previously determined seed is provided as a determined seed.
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