## 2 Overviews of Both the 5G AKA Protocol and the 5G-IPAKA Protocol
### The 5G AKA Protocol
Similarly, the UE cannot find whether \(SUCI\) is a replayed message because \(AUTN\) does not contain the challenge of the UE (i.e., \(x\)), which is included in \(SUCI\) generated by the UE. * Mutual authentication between the UE and the SN cannot be established. The UE cannot authenticate the SN because \(AUTN\) does not contain \(SNN\). Similarly, the SN cannot authenticate the UE for the following three reasons. Firstly, the SN does not verify \(SUCI\), \(AUTN\), \(HXRES^{*}\), \(RES^{*}\), and \(AUTS\). Secondly, the second received message of the SN does not contain \(SUPI\) to match with \(SUCI\) in the first received message of the SN. Finally, the last received message of the SN does not contain \(RAND\), meaning that \(SUPI\) in the last received message of the SN cannot match the UE's identity in \(AUTN\) and \(HXRES^{*}\), which are included in the second received message of the SN. * \(K_{SEAF}\) cannot reach an agreement. The last received message of the SN does not contain \(RAND\), so this message can be a replayed message, meaning that \(K_{SEAF}\) on the SN is not equal to \(K_{SEAF}\) on the HN. As a result, \(K_{SEAF}\) on the SN is also not equal to \(K_{SEAF}\) on the UE. * Location privacy of the UE can be compromised. Because \(AUTN\) does not contain the challenge of the UE (i.e., \(x\)), the first received message of the UE can be a replayed message. If \(SQN\subset AUTN\) is in the correct range, then the location of the UE can be compromised by reidentifying \(RES^{*}\). If \(SQN\subset AUTN\) is not in the correct range, then the location privacy of the UE can be compromised by identifying the \"Synchronizationfailure\" indication. That is to say, when the first received message of the UE is replayed, the legitimate UE responds to \(RES^{*}\) or a \"Synchronization failure\" indication, but any other UE responds to a \"MAC failure\" indication. As a result, the location privacy of the legitimate UE can be compromised. * DoS attacks against the SN can be formed. Because the received messages of the SN do not contain the challenge of the SN, these messages can be some replayed messages. As a result, the penetrator can impersonate both the UE and the HN to complete the entire 5G AKA protocol with the SN, forming DoS attacks against the SN. * Attacks based on MAC failure can be performed. Firstly, the penetrator can forge or tamper with the first received message of the UE to make the UE respond to a \"MAC failure\" indication, resulting in authentication failure. Secondly, the penetrator can directly send a \"MAC failure\" indication to the SN, causing authentication failure. Finally, the penetrator can also replay a \"MAC failure\" indication between the SN and the HN, causing authentication failure. * Perfect forward secrecy cannot be provided. In the latest version of the 5G AKA protocol, if \(K\) is leaked, then the penetrator can calculate \(K_{AUSF}\) and \(K_{SEAF}\) based on those messages transmitted in the past run of the protocol. As a result, the penetrator can decrypt those encrypted communication messages transmitted in the past run of the protocol. Therefore, the latest version of the 5G AKA protocol cannot provide perfect forward secrecy.