scholarly journals Lattice Based Mix Network for Location Privacy in Mobile System

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Kunwar Singh ◽  
C. Pandu Rangan ◽  
A. K. Banerjee
Keyword(s):  
Polynomial Time ◽  
Location Privacy ◽  
Quantum Computer ◽  
Quantum Algorithm ◽  
Public Key ◽  
Mobile System ◽  
The Public ◽  
Diffie Hellman ◽  
Cryptographic Primitive ◽  
Time Quantum

In 1981, David Chaum proposed a cryptographic primitive for privacy calledmix network(Mixnet). A mixnet is cryptographic construction that establishes anonymous communication channel through a set of servers. In 2004, Golle et al. proposed a new cryptographic primitive called universal reencryption which takes the input as encrypted messages under the public key of the recipients not the public key of the universal mixnet. In Eurocrypt 2010, Gentry, Halevi, and Vaikunthanathan presented a cryptosystem which is an additive homomorphic and a multiplicative homomorphic for only one multiplication. In MIST 2013, Singh et al. presented a lattice based universal reencryption scheme under learning with error (LWE) assumption. In this paper, we have improved Singh et al.’s scheme using Fairbrother’s idea. LWE is a lattice hard problem for which till now there is no polynomial time quantum algorithm. Wiangsripanawan et al. proposed a protocol for location privacy in mobile system using universal reencryption whose security is reducible to Decision Diffie-Hellman assumption. Once quantum computer becomes a reality, universal reencryption can be broken in polynomial time by Shor’s algorithm. In postquantum cryptography, our scheme can replace universal reencryption scheme used in Wiangsripanawan et al. scheme for location privacy in mobile system.

scholarly journals BESTIE: Broadcast Encryption Scheme for Tiny IoT Equipment

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1389
Author(s):  
Jiwon Lee ◽  
Jihye Kim ◽  
Hyunok Oh
Keyword(s):  
The Other ◽  
Public Key ◽  
Broadcast Encryption ◽  
Encryption Scheme ◽  
The Public ◽  
Private Key ◽  
Diffie Hellman ◽  
The Standard Model ◽  
Encryption Decryption ◽  
Subset Difference

In public key broadcast encryption, anyone can securely transmit a message to a group of receivers such that privileged users can decrypt it. The three important parameters of the broadcast encryption scheme are the length of the ciphertext, the size of private/public key, and the performance of encryption/decryption. It is suggested to decrease them as much as possible; however, it turns out that decreasing one increases the other in most schemes. This paper proposes a new broadcast encryption scheme for tiny Internet of Things (IoT) equipment (BESTIE), minimizing the private key size in each user. In the proposed scheme, the private key size is O(logn), the public key size is O(logn), the encryption time per subset is O(logn), the decryption time is O(logn), and the ciphertext text size is O(r), where n denotes the maximum number of users, and r indicates the number of revoked users. The proposed scheme is the first subset difference-based broadcast encryption scheme to reduce the private key size O(logn) without sacrificing the other parameters. We prove that our proposed scheme is secure under q-Simplified Multi-Exponent Bilinear Diffie-Hellman (q-SMEBDH) in the standard model.

scholarly journals Survey on Asymmetric Key Cryptographic Algorithms

2020 ◽  
pp. 404-408
Author(s):  
Sabitha S ◽  
Binitha V Nair
Keyword(s):  
Public Key Cryptography ◽  
Public Key ◽  
The Public ◽  
Private Key ◽  
Design And Implementation ◽  
Diffie Hellman ◽  
Encryption And Decryption ◽  
Cryptographic Algorithms ◽  
Symmetric Key ◽  
Symmetric Key Cryptography

Cryptography is an essential and effective method for securing information’s and data. Several symmetric and asymmetric key cryptographic algorithms are used for securing the data. Symmetric key cryptography uses the same key for both encryption and decryption. Asymmetric Key Cryptography also known as public key cryptography uses two different keys – a public key and a private key. The public key is used for encryption and the private key is used for decryption. In this paper, certain asymmetric key algorithms such as RSA, Rabin, Diffie-Hellman, ElGamal and Elliptical curve cryptosystem, their security aspects and the processes involved in design and implementation of these algorithms are examined.

scholarly journals Polynomial-time quantum algorithm for the simulation of chemical dynamics

2008 ◽  
Vol 105 (48) ◽  
pp. 18681-18686 ◽  
Author(s):  
I. Kassal ◽  
S. P. Jordan ◽  
P. J. Love ◽  
M. Mohseni ◽  
A. Aspuru-Guzik
Keyword(s):  
Polynomial Time ◽  
Quantum Algorithm ◽  
Chemical Dynamics ◽  
Time Quantum

Quantum Chemistry on Quantum Computers: A Polynomial-Time Quantum Algorithm for Constructing the Wave Functions of Open-Shell Molecules

2016 ◽  
Vol 120 (32) ◽  
pp. 6459-6466 ◽  
Author(s):  
Kenji Sugisaki ◽  
Satoru Yamamoto ◽  
Shigeaki Nakazawa ◽  
Kazuo Toyota ◽  
Kazunobu Sato ◽  
...  
Keyword(s):  
Quantum Chemistry ◽  
Polynomial Time ◽  
Quantum Algorithm ◽  
Open Shell ◽  
Wave Functions ◽  
Quantum Computers ◽  
Time Quantum

scholarly journals Efficient quantum algorithms for the hidden subgroup problem over semi-direct product groups

2007 ◽  
Vol 7 (5&6) ◽  
pp. 559-570
Author(s):  
Y. Inui ◽  
F. Le Gall
Keyword(s):  
Direct Product ◽  
Polynomial Time ◽  
Efficient Algorithm ◽  
Quantum Algorithms ◽  
Quantum Algorithm ◽  
Black Box ◽  
Hidden Subgroup Problem ◽  
Time Quantum ◽  
Subgroup Problem

In this paper, we consider the hidden subgroup problem (HSP) over the class of semi-direct product groups $\mathbb{Z}_{p^r}\rtimes\mathbb{Z}_q$, for $p$ and $q$ prime. We first present a classification of these groups in five classes. Then, we describe a polynomial-time quantum algorithm solving the HSP over all the groups of one of these classes: the groups of the form $\mathbb{Z}_{p^r}\rtimes\mathbb{Z}_p$, where $p$ is an odd prime. Our algorithm works even in the most general case where the group is presented as a black-box group with not necessarily unique encoding. Finally, we extend this result and present an efficient algorithm solving the HSP over the groups $\mathbb{Z}^m_{p^r}\rtimes\mathbb{Z}_p$.

scholarly journals Implementation of a New Strongly-Asymmetric Algorithm and Its Optimization

Cryptography ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 21
Author(s):  
Koki Jimbo ◽  
Satoshi Iriyama ◽  
Massimo Regoli
Keyword(s):  
General Framework ◽  
Key Agreement ◽  
Public Key ◽  
Security Level ◽  
The Public ◽  
High Speeds ◽  
Diffie Hellman ◽  
New Public ◽  
Public Keys ◽  
Free Parameters

A new public key agreement (PKA) algorithm, called the strongly-asymmetric algorithm (SAA-5), was introduced by Accardi et al. The main differences from the usual PKA algorithms are that Bob has some independent public keys and Alice produces her public key by using some part of the public keys from Bob. Then, the preparation and calculation processes are essentially asymmetric. This algorithms has several free parameters more than the usual symmetric PKA algorithms and the velocity of calculation is largely dependent on the parameters chosen; however, the performance of it has not yet been tested. The purpose of our study was to discuss efficient parameters to share the key with high speeds in SAA-5 and to optimize SAA-5 in terms of calculation speed. To find efficient parameters of SAA-5, we compared the calculation speed with Diffie–Hellman (D-H) while varying values of some parameters under the circumstance where the length of the secret shared key (SSK) was fixed. For optimization, we discuss a more general framework of SAA-5 to find more efficient operations. By fixing the parameters of the framework properly, a new PKA algorithm with the same security level as SAA-5 was produced. The result shows that the calculation speed of the proposed PKA algorithm is faster than D-H, especially for large key lengths. The calculation speed of the proposed PKA algorithm increases linearly as the SSK length increases, whereas D-H increases exponentially.

scholarly journals A Certificateless Noninteractive Key Exchange Protocol with Provable Security

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Xuefei Cao ◽  
Lanjun Dang ◽  
Yingzi Luan ◽  
Wei You
Keyword(s):  
Random Oracle Model ◽  
Random Oracle ◽  
Key Exchange ◽  
Public Key ◽  
Communication Overhead ◽  
Key Exchange Protocol ◽  
The Public ◽  
Diffie Hellman ◽  
Message Exchange ◽  
Certificateless Public Key Cryptosystem

In this paper, we propose a certificateless noninteractive key exchange protocol. No message exchange is required in the protocol, and this feature will facilitate the applications where the communication overhead matters, for example, the communications between the satellites and the earth. The public key certificate is removed as well as the key escrow problem using the certificateless public key cryptosystem. The security of the protocol rests on the bilinear Diffie–Hellman problem, and it could be proved in the random oracle model. Compared with previous protocols, the new protocol reduces the running time by at least 33.0%.

scholarly journals A Visual Cryptographic Technique for Transferring Secret Image in Public Cloud

2020 ◽  
Vol 9 (3) ◽  
pp. 2257-2260
Keyword(s):  
Computational Cost ◽  
Visual Cryptography ◽  
Public Key ◽  
Public Cloud ◽  
Secret Key ◽  
The Public ◽  
Secret Image ◽  
Private Key ◽  
Diffie Hellman ◽  
Client System

The use of “Asymmetric Cryptography” provides the way to avail the feature of non-repudiation, encryption of data and defining the user digital identity to map with the authenticating user in the Public Cloud. A security technique is to be provided for the data even before it is stored on the Cloud. The public key certificate can be transferred into key server for encrypting the data by other users or devices in the public cloud. By using OpenPGP standard (PGP)/GNU Privacy Guard (GnuPG), public key certificate and the private key certificate can be generated by the user in the client system itself. The client private key can never be moved out from the client system and users only responsibility is to decrypt their data like images. This methodology will be very much suitable for authenticating, transferring, accessing and storing the images in the Public Cloud. The computational cost for encrypting the whole image with public key will be huge and so the hybrid methodology is proposed with visual cryptography technique and Elliptic-Curve Diffie–Hellman (ECDH) methodology. This paper proposes secure transfer of secret image by using visual cryptography technique and thereby modifying any one of the visual shares into encrypted data with ECDH secret key and finally converted those two shares into base64 format. The proposed algorithm is implemented by using the Python language and their results are discussed with sample images.

Key Management

2011 ◽  
pp. 88-113
Author(s):  
Chuan-Kun Wu
Keyword(s):  
Secret Sharing ◽  
Key Management ◽  
Key Agreement ◽  
Public Key ◽  
Key Escrow ◽  
The Public ◽  
Cryptographic Algorithm ◽  
Diffie Hellman ◽  
Public Networks ◽  
Active Attacks

In secure communications, key management is not as simple as metal key management which is supposed to be in a key ring or simply put in a pocket. Suppose Alice wants to transmit some confidential information to Bob over the public networks such as the Internet, Alice could simply encrypt the message using a known cipher such as AES, and then transmit the ciphertext to Bob. However, in order to enable Bob to decrypt the ciphertext to get the original message, in traditional cipher system, Bob needs to have the encryption key. How to let Alice securely and efficiently transmit the encryption key to Bob is a problem of key management. An intuitive approach would be to use a secure channel for the key transmission; this worked in earlier years, but is not a desirable solution in today’s electronic world. Since the invention of public key cryptography, the key management problem with respect to secret key transmission has been solved, which can either employ the Diffie-Hellman key agreement scheme or to use a public key cryptographic algorithm to encrypt the encryption key (which is often known as a session key). This approach is secure against passive attacks, but is vulnerable against active attacks (more precisely the man-in-the-middle attacks). So there must be a way to authenticate the identity of the communication entities. This leads to public key management where the public key infrastructure (PKI) is a typical set of practical protocols, and there is also a set of international standards about PKI. With respect to private key management, it is to prevent keys to be lost or stolen. To prevent a key from being lost, one way is to use the secret sharing, and another is to use the key escrow technique. Both aspects have many research outcomes and practical solutions. With respect to keys being stolen, another practical solution is to use a password to encrypt the key. Hence, there are many password-based security protocols in different applications. This chapter presents a comprehensive description about how each aspect of the key management works. Topics on key management covered by this chapter include key agreement, group-based key agreement and key distribution, the PKI mechanisms, secret sharing, key escrow, password associated key management, and key management in PGP and UMTS systems.

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