| 摘要 |
<p>A method of obtaining descrambling information at a receiver, the descrambling information for enabling descrambling of scrambled content, the method comprising: using a provider verification key to access a software image, said software image having been secured by a provider using a provider signature key corresponding to the provider verification key; receiving a secured version of the descrambling information; using the accessed software image to obtain virtual descrambling information from the secured version of the descrambling information; providing the virtual descrambling information and said provider verification key as inputs to a cryptographic function to produce a given output comprising said descrambling information, wherein the cryptographic function has the property that it is infeasible to determine a key pair including a signature key and a verification key associated with the signature key, and another virtual descrambling information, such that the determined verification key and the another virtual descrambling information map to the given output of the cryptographic function.</p> |
