Blockchain Privacy Protection Based on Post Quantum Threshold Algorithm

With the rapid increase in demand for data trustworthiness and data security,distributed data storage technology represented by blockchain has received unprecedented attention.These technologies have been suggested for various uses because of their remarkable ability to offer decentralization,high autonomy,full process traceability,and tamper resistance.Blockchain enables the exchange of information and value in an untrusted environment.There has been a significant increase in attention to the confidentiality and privacy preservation of blockchain technology.Ensuring data privacy is a critical concern in cryptography,and one of the most important protocols used to achieve this is the secret-sharing method.By dividing the secret into shares and distributing them among multiple parties,no one can access the secret without the cooperation of the other parties.However,Attackers with quantum computers in the future can execute Grover’s and Shor’s algorithms on quantum computers that can break or reduce the currently widely used cryptosystems.Furthermore,centralized management of keys increases the risk of key leakage.This paper proposed a post-quantum threshold algo-rithm to reduce the risk of data privacy leakage in blockchain Systems.This algorithm uses distributed key management technology to reduce the risk of individual node private key leakage and provide post-quantum security.The proposed privacy-preserving cryptographic algorithm provides a post-quantum threshold architecture for managing data,which involves defining users and interaction processes within the system.This paper applies a linear secret-sharing solution to partition the private key of the Number Theory Research Unit(NTRU)algorithm into n parts.It constructs a t–n threshold that allows recovery of the plaintext only when more than t nodes participate in decryption.The characteristic of a threshold makes the scheme resistant to collusion attacks from members whose combined credibility is less than the threshold.This mitigates the risk of single-point private key leakage.During the threshold decryption process,the private key information of the nodes will not be leaked.In addition,the fact that the threshold algorithm is founded on the NTRU lattice enables it to withstand quantum attacks,thus enhancing its security.According to the analysis,the proposed scheme provides superior protection compared to currently availablemethods.This paper provides postquantum security solutions for data security protection of blockchain,which will enrich the use of blockchain in scenarios with strict requirements for data privacy protection.

Robust Threshold Guillou-Quisquater Signature Scheme

The deficiencies of the first threshold Guilbu-Quisquater signature schemepresented by Li-San Liu, Cheng-Kang Chu and Wen-Guey Tzeng arc analysiscd at first, and then a newthreshold Guillou-Quisquater signature scheme is presented. The new scheme isunforgeable and robustagainst any adaptive adversary if the base Guillou-Quisquater signature scheme is unforgeable underthe chosen message attack and computing the discrete logarithm modulo a prime is hard This schemecan also achieve optimal resilience. However, the new scheme does not need the assumption that N isthe product of two safe primes. The basie signature scheme underlying the new scheme is exactlyGuillou-Quisqualtr signature scheme, and the additional strong computation assumption introduced bythe first threshold Guillou-Quisquater scheme is weaken.

Complex Threshold Key Management for Ad Hoc Network

A complex threshold key management framework has been proposed, which canaddress the challenges posed by the unique nature of Ad hoc network. Depending on the cooperation ofthe controller and participation nodes, this scheme should be efficient in the operationenvironmental alteration and toleianl faults of node, which take the advantages of the benefits ofboth key management approaches and alleviate their limitations. For the cooperation of thecontroller and participation nodes, a (t, n) threshold Elliptic curve sign-encryption scheme withthe specified receiver also has been proposed. Using this threshold sign-encryption scheme, the keymanagement distributes the trust between a controller and a set of participation nodes.

Trusted Routing Based on Identity-Based Threshold Signature for Opportunistic Networks

In opportunistic Networks,compromised nodes can attack social context-based routing protocols by publishing false social attributes information.To solve this problem,we propose a security scheme based on the identity-based threshold signature which allows mobile nodes to jointly generate and distribute the secrets for social attributes in a totally self-organized way without the need of any centralized authority.New joining nodes can reconstruct their own social attribute signatures by getting enough partial signature services from encounter opportunities with the initial nodes.Mobile nodes need to testify whether the neighbors can provide valid attribute signatures for their routing advertisements in order to resist potential routing attacks.Simulation results show that:by implementing our security scheme,the network delivery probability of the social context-based routing protocol can be effectively improved when there are large numbers of compromised nodes in opportunistic networks.

A New Communication Scheme for Threshold Certificate Authority in Ad Hoc Networks

We present a new approach to reduct the com--munication overhead caused bythreshold cryptography using modified multicast protocol and certificate proxy technology. Servernodes maintain a few multicast groups proactively. A client wanting to updateits certificatemulticasts its request to a server nocks group through its certificate proxy. At periodic intervals,server nodes refresh their shares of the private key of certificate authority using multicast.

SLID: A Secure Lowest-ID Clustering Algorithm

In order to solve security problem of clustering algorithm, we proposed amethod to enhance the security of the well-known lowest-ID clustering algorithm. This method isbased on the idea of the secret sharing and the (k, n) threshold cryptography, Each node, whetherclusterhead or ordinary member, holds a share of the global certificate, and any k nodes cancommunicate securely. There is no need for any clusterhead to execute extra functions more thanrouting. Our scheme needs some prior configuration before deployment, and can be used in criticalenvironment with small scale. The security-enhancement for Lowest-ID algorithm can also be appliedinto other clustering approaches with minor modification. The feasibility of this method wasverified bythe simulation results.

Efficient and Robust Two-Party RSA Key Generation

An efficient two party RSA secret key sharing generation scheme based on a homomorphic encryption, which is semantically secure under the prime residuosity assumption, is proposed in this paper. At the stage of computing RSA modulo N, an initial distributed primality test protocol is used to reduce the computation complexity and increase the probability of N being a two-prime product. On the other aspect, the homomorphic encryption based sharing conversion protocols is devised and adopted in multi-party computing modulus N and secret key d. Comparing to any sharing conversion protocols based on oblivious transfer protocol, the homomorphic encryption based sharing conversion protocols are of high performance. Our scheme resists the passive attack and since a method of verifying the sharing was introduced in, the scheme can resists any cheating behaviors too. Security proof, computation complexity and communication complexity analysis are given at last.

A threshold key escrow scheme based on public key cryptosystem

In key escrow field it is important to solve the problem thatuser's secret key completely depends on the trusted escrow agency. In 1995, some methods of solving the problem were presented. But these methods are no better than that of directly using threshold cryptography. In this paper, we present a common pattern of threshold key escrow scheme based on public key cryptosystem, and a detailed design based on the improved RSA algorithm is given. The above problem is solved by this scheme.

Reaching consensus for membership dynamic in secret sharing and its application to cross-chain

The communication efficiency optimization,censorship resilience,and generation of shared randomness are inseparable from the threshold cryptography in the existing Byzantine Fault Tolerant(BFT)consensus.The membership in consensus in a blockchain scenario supports dynamic changes,which effectively prevents the corruption of consensus participants.Especially in cross-chain protocols,the dynamic access to different blockchains will inevitably bring about the demand for member dynamic.Most existing threshold cryptography schemes rely on redefined key shares,leading to a static set of secret sharing participants.In this paper,we propose a general approach to coupling blockchain consensus and dynamic secret sharing.The committee performs consensus confirmation of both dynamic secret sharing and transaction proposals.Our scheme facilitates threshold cryptography membership dynamic,thus underlying support for membership dynamic of threshold cryptographybased BFT consensus schemes.We instantiate a dynamic HotStuff consensus to demonstrate the effectiveness of the scheme.After the correctness and security proof,our scheme achieves the secrecy and integrity of the threshold key shares while ensuring consensus liveness and safety.Experimental results prove that our scheme obtains dynamic membership with negligible overhead.