Patent Document ID: 9473463
Application ID: 14445799

Base Claim:
1. A method comprising: caching concurrently, by a computing device, a first set of control words and a first set of entitlement control messages (ECMs) associated with the first set of control words; encrypting a transport stream, for a first service, using a first control word of the first set of control words during a first cryptographic period; encrypting the transport stream, for the first service, using a second control word of the first set of control words different from the first control word during a second cryptographic period, wherein the second cryptographic period occurs after the first cryptographic period; encrypting the transport stream, for the first service, using the first control word of the first set of control words during a third cryptographic period, wherein the third cryptographic period occurs after the first cryptographic period and the second cryptographic period; inserting into the transport stream, for the first service, a first ECM, of the first set of ECMs, corresponding to the first control word; and sending, to a device downstream from the computing device, the transport stream.

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Claim 7:
7. The method of claim 1 , further comprising: after sending to the device downstream from the computing device a last ECM of the first set of ECMs, sending, by the computing device and to the device downstream from the computing device, the first ECM of the first set of ECMs used to calculate the first control word for use during another cryptographic period different from the first cryptographic period.