| 摘要 |
<p>A modem unit and the like receive packets sent from a base station apparatus and receives packets sent from other terminal apparatuses. A processing unit processes the received packets. For the packets received by the modem unit and the like from the base station apparatus, a private key complying with a public key cryptosystem is used for a digital signature, whereas a symmetric key complying with a symmetric key cryptosystem is used for data. For the packets received from the other terminal apparatuses, a symmetric key complying with the symmetric key cryptosystem is used for the digital signature.</p> |
