# A Practical and Efficient Node Blind SignCryption Scheme for the IoT Device Network
## 2 Related Work and Security Definitions  
### Related Work  
In this section, we discuss the related research proposed in [1; 2; 3; 4]. In [1], the authors propose a \(\mathcal{CPAS}\) scheme for the vehicular sensor network and assume that there exists two TAs, where one is a tracing Authority (TRA for short) and the other is a public key generation center (PKG for short) for tracing the identity and key pairs of all vehicles, respectively. The TRA can produce a pseudo-ID for all vehicles after it has verified the real identity from them. The PKG also can generate the key-pairs for these vehicles. If there is a dispute in the protocol, the TRA can determine the real identity of the pseudo-ID key-pair through the help of the PKG. At this time, each vehicle does not show its real identity through the above scheme's methodology. On the other hand, we can discover that the total efficiency computation of this scheme is \(3 Pa+1 SM\) for signature verification operation and \(3 Pa+(n+1)SM\) for \(n\) signatures batch verification, where \(Pa\) is a pairing operation and \(SM\) is a symmetric encrypting operation. We consider that the pairing operation is demanding for comparing our scheme with others in Table 1 for Internet of Things (IoT for short) devices. From the efficiency comparison in Table 1, we can see that our approach is much more efficient than [1]. In [2], we observed that authors also claim their scheme is more efficient than those in other articles [3; 4]. However, this paper [2] is still slower than our proposed approach in Table 1.  
On one hand, from the data authentication aspect, the gateway is unaware of what the sensor node's data are in our approach. The sensor node will blind the forward data first before sending these data to the gateway. On the other hand, the gateway also provides its own random parameters during the signature generation of the offline-sign-cryption phase. This means that each signature is generated by the gateway's signing parameters and the sensor node's parameters after the above offline-sign-cryption and online-sign-cryption phases. Meanwhile, our approach can guarantee the situation where the signer cannot fully control the signature generation and provide the unlinkability to the signature. In [3], the authors provide an efficient sign-cryption methodology between the traditional public key crypto-system to the identity-based crypto-system and vice versa. This can be applied in the multireceiver construction for the IoT device network and provides a general prototype for this crypto-system transformation. We think that this idea is effective and suitable for the IoT device to transfer sensing data to another crypto-system construction. However, the sensing node still requires great computation effort on the paring operation and can cause a performance bottleneck on these sensor nodes. We also see in [3] that its computation cost is about \(3\ Pa\), where \(Pa\) is a pairing operation on a large prime number \(q\). Finally, in [4], the authors claim their approach is only about \(4\ Mu+2\ Pa\), where \(Mu\) is the modular multiplication and \(Pa\) is the paring operation. After converting to the final computation approximately, we discover that this scheme still costs \(409\ Mu\) more than ours in Table 1. In this approach, our contribution is to construct an efficient methodology that can generate a signature and encryption based on the QR at the same time and also preserve a concrete security proof on well-known hard problems such as the RSA factoring problem [11].