| 摘要 |
A method and apparatus for providing information about an encrypted signal transmitted by a satellite in a satellite navigation system are disclosed. A data sequence of the encrypted signal as transmitted is obtained, a signal sample is extracted from the data sequence, the signal sample including a part of the data sequence having a length less than a total length of the data sequence, and the signal sample and information about when the data included in the signal sample was transmitted by the satellite are transmitted, as the encrypted signal information, to a receiver for use in the satellite navigation system. A method and apparatus for authenticating an unencrypted signal based on the encrypted signal information are also disclosed. In particular, a time offset between an internal clock of the receiver and an internal clock of the satellite is obtained based on the unencrypted signal, the encrypted signal information is received, a portion of the received encrypted signal is identified that is expected to correspond to the signal sample based on the obtained time offset, the identified portion is correlated with the signal sample, and it is determined that the received unencrypted signal is authentic if a predetermined threshold correlation is obtained. |
