Implementation of Algorithms for Identity Based Encryption and Decryption

The rapid development of network technology has brought new challenges to data security. As the first gateway of a certain mobile internet system, access authentication is an essential step that guarantees the internal security of the network. However, there are some problems in traditional cryptosystem-based authentication mechanisms, such as certificate management problem and centralized key escrow problem. Centralized storage of user information is restricted by the server, the security of the server is not within the user’s control, the stability of the server cannot be guaranteed, and personal privacy on the server may be leaked. In this paper, we focus on the private key escrow problem caused by the Private Key Generator (PKG) in Identity-Based Cryptosystems (IBC) mechanism and propose a Blockchain-assisted user public-private key generation scheme (BAKG) which introduces the blockchain to improve the robustness and reliability of key management. In BAKG, the user’s private key is determined by itself through combining the partial private keys from different PKGs, which prevents the risk of private key exposure caused by a single PKG. Meanwhile, based on the theory of the Combined Public Key (CPK) algorithm, we have designed a feasible blockchain-based key generation logic and developed a prototype authentication system based on the above concept. We further analyze the security of BAKG and the analytical results show that BAKG can meet various security requirements. In addition, according to the performance evaluation results, BAKG has good performance in both read/write consensus and different key length calculations, which means it has good potential for lightweight authentication applications.KeywordsBlockchainAuthenticationIdentity-Based CryptosystemsCombine public key

The objective of the PKA encryption scheme is to complement, or replace, existing Public Key Infrastructures (PKI) [1]. In this scheme, the initialization step is based on the secure exchange of addressable cryptographic tables between the communicating parties. These tables are generated either with random numbers, or with arrays of addressable Physical Unclonable Function (PUFs). The subsequent communications between the parties can therefore occurs over untrusted channels, by exchanging dynamically generated public keys. Private keys are, generated independently with all communicating parties using their cryptographic tables, and the shared public keys. The private keys are combined with methods such as the Advanced Encryption Standard (AES) to encrypt and decrypt the communication between users. The generation of private keys is done without mathematical computations that are potentially vulnerable to quantum computers using algorithms such as the one developed by Shor [2]. PKA is fast and requires approximately 800 CPU clock cycles. We implemented, and tested the PKA dynamic key exchange scheme in legacy systems to secure PC-to-PC communication, and PC to smart card communication with AES.

In 1984, Shamir proposed the concept of the ID-based cryptosystem (IBC). Instead of generating and publishing a public key for each user, the ID-based scheme permits each user to choose his name or network address as his public key. This is advantageous to public-key cryptosystems because the public-key verification is so easy and direct. In such a way, a large public key file is not required. Since new cryptographic schemes always face security challenges and many integer factorization and discrete logarithm based cryptographic systems have been deployed, therefore, the purpose of this paper is to design a transformation process that can transfer the entire integer factorization problem and discrete logarithm problem based cryptosystems into the ID-based systems rather than re-invent a new system. We consider the security against a conspiracy of some entities in the proposed system and show the possibility of establishing a more secure system. Rapid advances in computer technology and the development of the Internet are changing the way, we conduct our daily and business lives. Secrecy is an important issue with respect to sensitive data transferred over insecure public channels. In an open network environment, secret session key needs to be shared between two users before it establishes a secret communication. While the number of users in the network is increasing, key distribution will become a serious problem. In 1976, Diffie and Hellman (4) introduced the concept of the public key distribution system (PKDS). In the PKDS, each user needs to select a secret key and compute a corresponding public key and store in the public directory. The common secrete session key, which will be shared between two users can then be determined by either user, based on his own secret key and the partner's public key. Although the PKDS provides an elegant way to solve the key distribution problem, the major concern is the authentication of the public keys used in the cryptographic algorithm. Many attempts have been made to deal with the public key authentication issue. Kohnfelder (5) used the RSA digital signature scheme to provide public key certification. His system involves two kinds of public key cryptography: one is in modulo p, where p is a large prime number; the other is in modulo N, where N = pq, and p and q are large primes. Blom (7) proposed a symmetric key generation system (SKGS) based on secret sharing schemes. The problems of SKGS however, are the difficulty of choosing a suitable threshold value and the requirement of large memory space for storing the secret shadow of each user. In 1984, Shamir (1) introduced the concept of an identity. In this system, each user needs to visit key authentication center (KAC) and identify himself before joining the network. Once a user's identity is accepted, the KAC will provide him with a secret key.

Blockchain is an up-and-coming technology, and it is exploring its existence in all our day-to-day lives, particularly for business applications. Due to this, security has become a major and a higher priority concern during the transaction process of data, cryptocurrency, etc. Achieving integrity, authentication, and non-repudiation with blockchain technology through digital signatures are the factors for its success. Hence, we imply a novel hybrid chaotic map–based proactive RSA/digital signature scheme for a better securable transaction of blocks compared to earlier works. Faster encryption and decryption could be expected by this novel approach. This could surely be resistant to brute force attacks, chosen plain text attacks and chosen cipher text attacks. OPENMP and OPENSSL libraries could be employed for good performance and security in a multicore platform. Chaotic map theory has its unique characteristics in the design of highly secure asymmetric encryption and decryption processes, with lesser computational cost in lesser time. The strength of RSA lies in the prime factorization of larger prime numbers in the generation of public and private keys. RSA has a severe backlog in computational time; while the length of the prime number is longer, to ensure higher security, the longer one is preferable. Hence to speedup the factorization process, chaotic mapping theory has been synchronized with the RSA cryptosystem. Second, chaotic mapping theory provides an enhanced avalanche effect, which leads to a two-factor RSA encryption process. Chaotic maps are highly sensitive to initial values and control parameters. The unique feature of inclusion of chaotic maps is that any slight change in the initial conditions of the plain text would cause a remarkable deviation in the message digest. This nature would make the hacker limit their prediction ability. Computational time, cost, and level of resistance to attacks are the factors to be considered to measure the efficiency of our new approach when compared to other RSA approaches. The work was simulated using MATLAB and it is proved that that the proposed RSA with hybrid GLT chaotic maps is 1.53 times and 1.27 times faster than the existing ones.

Provably secure identity-based authenticated key agreement protocols with malicious private key generators

Hierarchical Identity-Based Encryption (HIBE) is a generalization of Identity-Based Encryption (IBE) that mirrors an organizational hierarchy, however, the residual key escrow problem has still remained. This paper introduces a new scheme, based on the security notion of anonymous ciphertext indistinguishability against key generation center (ACI-KGC) security proposed by Chow, to remove the inherent key escrow problem. The scheme employs multiple Identity Certification Authorities (ICAs) which can ensure that the Private Key Generators (PKGs) distribute private key without knowing the list of user’s identity information, so as to prevent malicious PKGs from decrypting message on behalf of user or maliciously make user’s private key public. Security analysis shows that the scheme can solve the key escrow with keeping the high-efficiency and security of HIBE system. In contrast to Chen’s T-HIBE and Chow’s scheme, to generating the user’s private key, our scheme does not require the multiple KPAs or the complex interactive protocol which take too much extra computation costs. And comparing with GS-HIBE, our scheme focuses on solving the key escrow problem with outstanding performance and security of HIBE system.

In Identity-Based Encryption (IBE) system, the Private Key Generator (PKG) holds the master secret key and is responsible for generating private keys for the users. This incurs the key-escrow problem, i.e. the PKG can decrypt any user' any ciphertexts without any possible detection. Also, compromising the master secret key will enable an adversary to do anything to the whole system, and having the master secret key be unavailable implies that new users cannot obtain private keys from the PKG, and existing users cannot get their private keys back from the PKG when they lost them. To address the key-escrow problem and protect the master secret key as much as possible with strong security and availability, distributed PKG protocols supporting threshold policy have been adopted in some IBE schemes. In this paper, we propose a distributed PKG protocol that supports the policy to be any monotonic access structures. Also, we propose the first distributed PKG protocol that supports the dynamic changes of the PKGs and the policy, while remaining the master secret key unchanged. The two protocols do not need any third party acting as a trusted dealer to present, and the master secret key should never be generated or resided in any one single site. The protocols are applicable to a generic IBE template, which covers many existing important IBE schemes. When applied to this generic type of IBE schemes, the two distributed PKG protocols do not affect the encryption and decryption algorithms, and only each user knows his own private key.

Identity-based revocation system (IBRS) generates the ciphertext with a revoked identity list such that only the non-revoked identities can use their private keys to decrypt this ciphertext. IBRS can be efficiently applied in some practical applications, such as the pay-TV systems when the number of revoked identities are much less than the non-revoked ones. However, since IBRS is based on identity-based cryptography, it also suffers from the inherent key escrow problem where the private key generator (PKG) has full control of each user’s private key. As a consequence, it is hard to judge whether a pirated private key is generated by the PKG or the suspected user. There is no study on IBRS fulfilling accountability in literature to date. In this paper, we introduce the notion of accountable authority IBRS (A-IBRS), which provides accountability in IBRS schemes. In an A-IBRS, the aforementioned problem can be alleviated and resolved. Furthermore, a full black-box A-IBRS can distinguish the creator of a black box between the PKG and the associated user and the dishonest PKG is allowed to access the decryption results of the user private key. We formalize the definition and security models of the full black-box A-IBRS schemes. Then, we present a concrete full black-box A-IBRS scheme with constant-size master public key and private key. Finally, we prove the security of our scheme under the defined security models without random oracle.

In traditional public key signature, the public key of a signer is essentially a random string selected from a given set. It is infeasible to prove that a party is indeed the signer for a given signature. In general, the public key of a user needs a management authority to authenticate it. It results in that traditional public key cryptosystem (PKC) requires high maintenance cost for certificate management. Although, identity based cryptosystem (IBC) reduces the overhead of management, it suffers from the drawback of key escrow. Certificate-based cryptosystem combines the advantage of both PKC and IBC as it avoids the usage of certificates and does not suffer from key escrow. Recently, Liu et.al proposed an efficient Certificate-based signature and showed that the scheme was secure in the random oracles. Unfortunately, this paper shows that the scheme is insecure and discusses the flaws in their security proof. Then the corresponding attacks are given. To overcome the flaws, an improved scheme is proposed and the result shows that the scheme is provable secure against two game attacks of certificate-based signature in the random oracle model. The security is closely related to the computational Diffie-Hellman problem.KeywordsSecurity analysisattackimproved schemethe CDH problemcertificate-based signature

With the continuous development of quantum technology, the quantum signature as an application of quantum cryptography has received great attention. In this paper, we propose a public-key quantum group blind signature scheme based on single-qubit rotations. In this scheme, the group manager generates a public key. Each group member randomly generates his own private key according to the public key. The signer uses his private key and random sequence to generate the signature. The verifier uses the public key to verify the correctness of the quantum signature. The public and private keys can be reused, which simplifies the key management of the signature system. In this scheme, the random sequence is used to enhance the security of the scheme. At the same time, the quantum efficiency is improved by using single-qubit rotations. The security analysis shows that our scheme can ensure the security of the keys, the unforgeability and the non-deniability of the signature.

Data exchange has been rapidly increased recently by increasing the use of mobile networks. Sharing information (text, image, audio and video) over unsecured mobile network channels is liable for attacking and stealing. Encryption techniques are the most suitable methods to protect information from hackers. Hill cipher algorithm is one of symmetric techniques, it has a simple structure and fast computations, but weak security because sender and receiver need to use and share the same private key within a non-secure channel. Therefore, a novel hybrid encryption approach between elliptic curve cryptosystem and hill cipher (ECCHC) is proposed in this paper to convert Hill Cipher from symmetric technique (private key) to asymmetric one (public key) and increase its security and efficiency and resist the hackers. Thus, no need to share the secret key between sender and receiver and both can generate it from the private and public keys. Therefore, the proposed approach presents a new contribution by its ability to encrypt every character in the 128 ASCII table by using its ASCII value direct without needing to assign a numerical value for each character. The main advantages of the proposed method are represented in the computation simplicity, security efficiency and faster computation.

Currently, the pervasive cooperation of a group of Unmanned Aerial Vehicles (UAVs) has gained a lot of attention and use for its low price and widespread availability. For drones from different network domains to cooperate with each other, temporary Internet of Drones (IoD) is needed. The collaboration with drones requires frequent identity verification. However, owing to unreliable environment and weak connectivity of the IoD. Unmanned aerial vehicles (UAVs) are weak in energy, computing, cross-domain and memory resources. It is very difficult to design an efficient and the complete authentication scheme without abundant computing and memory resources. The conventional authentication methods are not suitable for IoD, Public Key Infrastructure (PKI) needs online and high bandwidth resources, at the same time, the construction and operation and maintenance costs of certificate authority (CA) are very high; Identity-Based Cryptograph (IBC) using a lot of operational resources, is a “heavy” algorithm, and in different domains (private key distribution from different Private Key Generator (PKG)) is difficult to authenticate each other. This paper proposes a two-layer lightweight key management scheme based on Unified Multi-domain Identity (UMI), which implement cross-domain authentication, effectively reduce the computing and traffic brought by public key certificate verification which is especially suitable for UAVs network. Finally, through verification, the scheme has better performance and security than other schemes.KeywordsUnmanned aerial vehicles (UAVs)Key authenticationPublic-key cryptographyInternet of Drones (IoD)

In 1984 Adi Shamir requested a solution for a novel public-key encryption scheme, called identity-based encryption (IBE). The original motivation for IBE was to help the deployment of a public-key infrastructure. The idea of an IBE scheme is that the public key can be any arbitrary string, for example, an email address, a name or a role. An IBE scheme does not need to download certificates to authenticate public keys as in a public-key infrastructure (PKI). A public key in an identity-based cryptosystem is simply the receiver’s identity, e.g. an email address. As often, when new technology occurs, the focus is on the functionality of the technology and not on its security. In this paper we briefly review about identity-based encryption and decryption. Later on we show that IBE schemes used for secure emailing render spamming far easier for spammers compared to if a PKI certificate approach is used.KeywordsWireless Sensor NetworkDestination NodeAdvance Encryption StandardCertificate AuthorityData Encryption StandardThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Chien et al. (2009) proposed an e-will system on the Internet using an identity-based cryptosystem. They claimed that their e-will system was secure enough to be used in practice since their system conforms to R.O.C. (Taiwan) Civil Law. However, we found several problems of Chien et al.'s scheme. First, the Trust Authority knows or can easily compute the user's private key. Therefore, it does not provide the non-repudiation property and it does not conform to the Electronic Signatures Act and the relevant regulations in the R.O.C. (Taiwan) government. Second, their scheme does not provide any long-term validation method of digital signatures. Therefore, we may fail to check the validity of the testator's will after death. To solve these problems, we propose a novel e-will system based on Government Public Key Infrastructure (GPKI) that can be used in practice.

In this paper, we propose two authenticated key distribution protocols and one conference key protocol using identity-based, self-certified public keys. These proposed protocols have the following properties:(i) No extra public key certificates and computational efforts are required for verification of authenticity for public keys.(ii) Key establishment and validation of the desired public keys are integrated in a logically single step.(iii) Each registering user can use his derived private key to check the validity of his public key issued by the system authority.(iv) The system authority cannot access to users' private keys. Hence, all private keys cannot be compromised in case of disruption or corruption of the system authority.(v) The proposed protocols provide the security property of key authentication whereby one user is assured that no other user aside from specifically identified user (s) may gain access to the derived shared key/conference key.