Authentication technology using QZSS

Abstract

We address in this paper about authentication of QZSS L1C/A signal using QZSS L1SAIF signal by developing an anti-spoofing methodology. The methodology is based on transmitting a signature data embedded into L1SAIF navigation message. The signature data is generated by using a part of L1C/A navigation message to generate Reference Authentication NAV Data (RAND). The RAND data is further encoded by LDPC based on a H-matrix. The LDPC encoded data is called signature data and is formatted to make it compatible with L1SAIF navigation message structure. This data is broadcasted from QZSS L1SAIF with a new message ID for authentication purpose. The receiver receives this message and decodes the authentication message into RAND and LDPC parity bits. Based on the information of RAND, the receiver gets corresponding H-matrix and other data from Authentication Data Center (ADC). These data from ADC is used to perform LDPC encoding to received RAND data. If the parity bits from this encoding are the same as the parity bits received by the receiver from L1SAIF signal are the same, it is concluded that the signals (L1C/A and L1SAIF) are authentic. Since, this method is based on using L1C/A navigation message for RAND and L1SAIF for broadcasting the signature data, it can also be implemented to other satellite systems like GPS L1C/A, MSAS, EGNOS and GAGAN.