| 摘要 |
A receiver comprises a security processor and a first memory that stores software code or second stage authentication key and a signature for the software or the second stage key. The receiver also stores a plurality of verification keys (PUAK). When the receiver is switched on or reset, the software or second stage key and the signature are loaded from the first memory. The security processor then loads a PUAK and uses it to verify the signature. In case of successful verification, the software code or second stage key is used and the verification method ends; it is then possible to activate CA specific functions in the receiver. However, if the verification is unsuccessful, then it is verified if there are untried PUAKs. If there are no untried signatures, then the verification has failed and the software cannot be verified; the verification method ends. If there are untried signatures, then the next PUAK is loaded.
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