Method and apparatus for generating pseudo random numbers in a video device having an embedded cipher unit
First Claim
1. In a video device, a method comprising:
- continuously clocking a cipher unit, upon power on or reset;
in response to a subsequent request after n clock cycles for a first pseudo random number taking a first plurality of output bits of the cipher unit and storing the first output bits;
upon storing the first output bits, outputting the stored first output bits as the first pseudo random number; and
transitioning to a selected one of the continuously clocking state, another output taking state, and an authenticated state depending on whether upon provision of the first pseudo random number, an indication of an unsuccessful authentication using the first pseudo random number, another request for a second pseudo random number, or an indication of a successful authentication using the first pseudo random number is received.
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Accused Products
Abstract
A video source device includes a cipher unit. The video source device uses the cipher unit to generate cipher bits for ciphering video to be transmitted to protect the video from unauthorized copying. The video source device authenticates video receiving devices using a symmetric ciphering/deciphering process that requires the video source device to generate and provide the video receiving device with a pseudo random number as the seed/basis number for the symmetric ciphering/deciphering process. The video source device is further provided with a state machine that controls the cipher unit to generate the required pseudo random number for the video source devices, thereby eliminating the need of having to provide separate circuitry to generate the required pseudo random numbers.
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Citations
11 Claims
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1. In a video device, a method comprising:
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continuously clocking a cipher unit, upon power on or reset;
in response to a subsequent request after n clock cycles for a first pseudo random number taking a first plurality of output bits of the cipher unit and storing the first output bits;
upon storing the first output bits, outputting the stored first output bits as the first pseudo random number; and
transitioning to a selected one of the continuously clocking state, another output taking state, and an authenticated state depending on whether upon provision of the first pseudo random number, an indication of an unsuccessful authentication using the first pseudo random number, another request for a second pseudo random number, or an indication of a successful authentication using the first pseudo random number is received. - View Dependent Claims (2, 3, 4)
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5. A video apparatus comprising:
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a cipher unit to generate a sequence of ciphering bits to cipher video to be transmitted by the video apparatus; and
a state machine coupled to the cipher unit to also use the ciphering unit to generate pseudo random numbers to authenticate video receiving devices attached to said video apparatus. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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Specification