Patent ID: 7426274

Claim:
A pseudo random number generator comprising: a cipher unit to generate a sequence of ciphering bits to cipher a stream of data including at least video data; and a state machine coupled to the cipher unit to also use the ciphering unit to generate a plurality of pseudo random numbers based on selected ones of said cipher bits wherein the state machine is equipped to transition to a continuous clocking state that includes, upon power on or reset, causing the cipher unit to be continuously clocked to introduce entropy into the cipher unit, wherein the state machine operates in one of four states: a continuous clocking state (E 0 ), a first cipher bit taking state (E 1 ), an output state (E 2 ), a second cipher bit taking state (E 3 ), and an active state (also referred to as the authenticated state), and during operating the state machine enters state E 0 upon power on and while in state E 0 , the state machine causes the cipher unit to be continuously clocked to incorporate entropy into the cipher unit, from state E 0 , the state machine transitions to state E 1 , first cipher bit taking state, upon receipt of a request for a first pseudo random number, after clocking the cipher units for n clocks, where n is an integer, in state E 1 , the state machine causes a number of output ciphering bits of the cipher unit to be taken and stored into a temporary storage location for output, from state E 1 , the state machine enters state E 2 , upon storing the taken ciphering bits, in state E 1 , the state machine causes the stored ciphering bits to be output as the requested pseudo random number, in state E 3 , the state machine causes a number of the output ciphering bits of the cipher unit to be taken and stored into a temporary storage location for output, in the active state, the cipher unit is used to generate ciphering bits to cipher the video before transmitting to a video receiving device and the cipher unit is not available for pseudo random number generation, from the active state, the state machine transitions back to E 0 , the continuous clocking state, if the authentication unit is notified of the video receiving device becoming unauthorized of becoming detached from the video source device.