A Low-Power Elliptic Curve Pairing Crypto-Processor for Secure Embedded Blockchain and Functional Encryption

Multi-input functional encryption, MIFE, is a powerful generalization of functional encryption that allows computation on encrypted data coming from multiple different data sources. In a recent work, Agrawal, Goyal, and Tomida (CRYPTO 2021) constructed MIFE for the class of quadratic functions. This was the first MIFE construction from bilinear maps that went beyond inner product computation. We advance the state-of-the-art in MIFE, and propose new constructions with stronger security and broader functionality. Stronger Security: In the typical formulation of MIFE security, an attacker is allowed to either corrupt all or none of the users who can encrypt the data. In this work, we study MIFE security in a stronger and more natural model where we allow an attacker to corrupt any subset of the users, instead of only permitting all-or-nothing corruption. We formalize the model by providing each user a unique encryption key, and letting the attacker corrupt all non-trivial subsets of the encryption keys, while still maintaining the MIFE security for ciphertexts generated using honest keys. We construct a secure MIFE system for quadratic functions in this fine-grained corruption model from bilinear maps. Our construction departs significantly from the existing MIFE schemes as we need to tackle a more general class of attackers. Broader Functionality: The notion of multi-client functional encryption, MCFE, is a useful extension of MIFE. In MCFE, each encryptor can additionally tag each ciphertext with appropriate metadata such that ciphertexts with only matching metadata can be decrypted together. In more detail, each ciphertext is now annotated with a unique label such that ciphertexts encrypted for different slots can now only be combined together during decryption as long as the associated labels are an exact match for all individual ciphertexts. In this work, we upgrade our MIFE scheme to also support ciphertext labelling. While the functionality of our scheme matches that of MCFE for quadratic functions, our security guarantee falls short of the general corruption model studied for MCFE. In our model, all encryptors share a secret key, therefore this yields a secret-key version of quadratic MCFE, which we denote by SK-MCFE. We leave the problem of proving security in the general corruption model as an important open problem.

Elliptic curves cryptography was introduced independently by Victor Miller (Miller, 1986) and Neal Koblitz (Koblitz, 1987(Koblitz, ) in 1985. .At that time elliptic curve cryptography was not actually seen as a promising cryptographic technique.As time progress and further research and intensive development done especially on the implementation side, elliptic curve cryptography is now being implemented widely.Elliptic curves cryptography offers smaller key size, bandwidth savings and faster in implementations when compared to the RSA (Rivest-Shamir-Adleman) cryptography which based its security on the integer factorization problem.The most interesting feature of the elliptic curves is the group structure of the points generated by the curves, where points on the elliptic curves form a group.The security of elliptic curves cryptography relies on the elliptic curves discrete logarithm problem.The elliptic curve discrete logarithm problem is analogous to the ordinary algebraic discrete logarithm problem, l = g x , where given the l and g, it is infeasible to compute the x.Elliptic curve discrete logarithm problem deals with solving for n the relation P = nG.Given the point P and the point G, then it is very hard to find the integer n.To implement the discrete logarithm problem in elliptic curve cryptography, the main task is to compute the order of group of the curves or in other words the number of points on the curve.Computation to find the number of points on a curve, has given rise to several point counting algorithms.The Schoof and the SEA (Schoof-Elkies-Atkin) point counting algorithms will be part of the discussion in this chapter.This chapter is organized as follows: Section 2, gives some preliminaries on elliptic curves, and in section 3, elliptic curve discrete logarithm problem is discussed.Some relevant issues on elliptic curve cryptography is discussed in section 4, in which the Diffie-Hellman key exchange scheme, ElGamal elliptic curve cryptosystem and elliptic curve digital signature scheme are discussed here accompanied with some examples.Section 5 discussed the two point counting algorithms, Schoof algorithm and the SEA (Schoof-Elkies-Atkin) algorithm.Following the discussion in section 5, section 6 summaries some similarities and the differences between these two algorithms.Section 7 gives some brief literature on these two point counting algorithms.Finally, section 8 is the concluding remarks for this chapter. Elliptic curvesElliptic curves obtained their name from their relation to elliptic integrals that arise from the computation of the arc length of ellipses (Lawrence & Wade, 2006).Elliptic curves are www.intechopen.com Cryptography and Security in Computing1 1 2 3 4 2 2 4 Fig. 1.1. 2(1 ) (1 ) yx x x   www.intechopen.com

In a traditional public key encryption system, data is encrypted to a particular individual who is fixed by a public key, and the revealed information is all-or-nothing. Functional encryption (FE) gives a new way of sharing encrypted data, with fine-grained control over revealed information on encrypted data. In FE, a secret key enables a user to learn a specific function of the encrypted data and nothing else. Attribute-based encryption (ABE) can specify a wide variety of receiver sets by using relation between key and cipher text parameters. This survey for a wide audience will first give the notions of FE, ABE (and attribute-based signatures (ABS)), and describe several practical applications of FE schemes on dual pairing vector spaces (DPVS). The cryptosystems are implemented by using a pairing operation on an elliptic curve, which has achieved many new applications including FE in recent years. We also give a brief summary of the mathematical mechanism, e.g., The algorithm, parameter selection, and underlying security.

The elliptic curve cryptography is almost used in the literature to develop the public key cryptosystems. A new general-purpose symmetric key cryptosystem using elliptic prime curves is proposed in this paper. For a given prime number P, there are many elliptic prime curves on which each point in the quadrant (0,0) to (P-1,P-1) lays. The set of minimum number of eligible elliptic prime curves for a given prime number P constitutes a lookup table that is the secret key of the proposed cryptosystem. The sender can pick up one eligible elliptic curve for each 2n-bit plaintext block. The sender sends two integers cipher for each 2n-bit plaintext block with encryption rate = 0.8. Moreover, a small prime number can be used efficiently with high security and good robustness against brute force attack.

A promising direction for constructing cryptographically stable pseudo-random sequence generators is an application of transformations in a group of points of elliptic and hypereliptic curves. This will allow building evidence-stable crypto algorithms, the problem of finding the private key in which is associated with solving a theoretically complex elliptic curve discrete logarithm problem. This paper proposes a method for generating pseudo-random sequences of the maximal period using transformations on elliptic curves. This method consists in the application of recurrent transformations with sequential formation of elements of points group of elliptic curves. This allows providing the maximum period of pseudo-random sequences with the reduction of the problem of finding the private key to the solution of the theoretically complex elliptic curve discrete logarithm problem. The block diagram of the device for generating pseudo-random sequences and the scheme for generating the internal states of the generator are given. We also present the results of statistical testing of some generators, which show that the generated sequences are indistinguishable in a statistical sense from truly random ones.KeywordsPseudo-random sequencesElliptic curvesMaximum period

PCAS: Cryptanalysis and improvement of pairing-free certificateless aggregate signature scheme with conditional privacy-preserving for VANETs

Attribute-based blind signature is used to realize the blind signature of messages by multiple people, and it is suitable for electronic payment services in the cloud. Most existing attribute-based blind signature schemes have complex bilinear pairing operations in the process of signature and verification, which leads to low algorithm efficiency. To solve this problem, in this study, an efficient pairing-free attribute-based blind signature scheme based on ordered binary decision diagram is proposed, and the security analysis of the new scheme is given under the difficulty of the elliptic curve discrete logarithm problem (ECDLP). The proposed scheme is based on elliptic curve cryptography (ECC). In this scheme, scalar multiplication on the elliptic curve, which is relatively lightweight, is used to replace bilinear pairing with a large computational cost in traditional attribute-based blind signature schemes. The computational overhead in the signature and verification processes is reduced, making the solution more suitable for resource-constrained cloud terminal user scenarios. On the other hand, in order to improve the computational efficiency of the attribute-based blind signature scheme, a more expressive and computationally efficient ordered binary decision diagram (OBDD) structure is used to construct the access structure of the signer. The OBDD access structure can simultaneously support the positive and negative values of attributes in the access structure at the same time. Compared with existing attribute-based blind signature schemes, the proposed scheme has better performance and storage, and meets the needs of resource-constrained cloud end users.

With the explosion of networks and the huge amount of data transmitted along, securing data content is becoming more and more important. Data encryption is widely used to ensure security in open networks such as the internet. This paper presents the implementation of stream cipher, where the key stream is generated based on the properties of Linear Feedback Shift Register and cyclic Elliptic Curve over a finite prime field. In this paper we illustrate the process of encryption/decryption of an image in spatial domain and also encrypt key file parameters needed for generating the key stream to other parties using Elliptic Curve Cryptography. Therefore the encrypted key file parameters are only transmitted and not the entire full-length key. Since Elliptic Curve Cryptography is replacing RSA for key exchange and Elliptic Curve based stream cipher offers a good choice for encryption in real time application. The strength of the proposed cipher lies in the generation of random sequence using Linear Feedback Shift Register over GF(p), difficulty of Elliptic Curve Discrete Logarithmic Problem and the entire key need not be transmitted in the encryption process. This paper also discusses the security aspects of the proposed cipher which is secure against all kinds of attacks.

Background: Today’s developing era data and information security plays an important role in unsecured communication between Internet of Things (IoT) elements. As the technologies are developing huge amount of information are exchanged with each other which increases the demand of a secure encryption standards. Objectives: To protect the information transmission between nodes in the perceptual layer of IoT, security is to be enhanced such that the Men in Middle (MIM) attack of information by intruders in the communication link is not possible. Methods/Statistical analysis: The security method is implemented using the concept of symmetric, asymmetric and hash algorithms between the sender and receiver. Elliptic Curve Cryptography (ECC) is performed for encrypting and sharing the Advanced Encryption Standard (AES) secret key between the sender and receiver. Elliptic Curve digital signature are added with the encrypted data for validation in transmission. Secured Hash Algorithm (SHA) is considered for generating Elliptical Curve Digital Signature Algorithm (ECDSA). All the algorithms are combined to enhance the security. Findings: Elliptic Curve Cryptography is generally applied for encrypting and sharing the secret key between the sender and receiver when Advanced Encryption Standard is used for encryption/decryption of data. A highly efficient architectures for asymmetric key encryption is applied with symmetric key encryption for encrypting the data transmitted between the devices present in the perceptual layers in the IoT. Due to security issues NIST selected SHA-3 Keccak-f[1600] algorithm. An authentication process based on ECC is applied to perceptual layer involving initialization and authentication phase apart from encryption and signature generation. Sender combines the encrypted data and key with signature together before transmitting to the receiver. The receiver verifies the signature and decrypts the key and obtains original information. Hence it is very difficult for the man in middle to access the information exchanged between the Perceptual Layer devices. Application/Improvements: This generally doesn’t require an innovative technique but an approach to develop the method implemented successfully in the perceptual layer of Internet of Things. The key is encrypted and decrypted using a novel ECC algorithm with improved ECDSA.

Elliptic curve cryptography (ECC) is based in one of the hardest arithmetic problems, the elliptic curve discrete logarithm problem, making ECC a reliable cryptographic technique. In addition to this advantage, ECC requires shorter keys compared to other public key algorithms, which suggests its use in low-end systems such as smart cards because of its efficiency and limited hardware requirements. Currently the leading smart card technology is Java card. Though both Java 2 standard edition (J2SE) 5.0 and Java card (JC) 2.2.1 include classes and interfaces making ECC available to Java programs, they are not complete, making it necessary to use additional, non-standard packages if the programmer wants to use ECC for different operations (digital signature, data encryption and decryption, etc.). In the present work, we provide a complete review of the state of the art of ECC in J2SE and Java card, with a complete list of operations available in both standard implementations and proprietary packages.

Nowadays there are more key technologies, such as cloud computing, big data, blockchain, and different techniques that process the data via a well-established purpose. The security of data should be a significant aspect of any type of system, therefore the systems should implement security techniques that solve this aspect. A relatively new encryption technique is searchable encryption, which enables the user to submit search queries based on chosen criteria (for example, keywords) to the cloud server on which the encrypted data (in the form of encrypted documents) is stored. Another emerging technology is blockchain, a decentralized approach for data sharing, based on a direct communication between two peers. To protect the data and its integrity, blockchain uses cryptographic mechanisms and strong mathematics computations as challenges that need to be solved by the nodes that adheres to the blockchain network. In this paper, we propose a searchable encryption scheme, which can be used in the cloud environment, based on elliptic curves and symmetric bilinear mapping for its algorithms and blockchain to store the indexes structure and to process the search query. Using elliptic curves, the proposed scheme is efficient, as it is proven in the literature that elliptic curve cryptography is usually faster than other encryption systems with the same level of security.

Due to reduced key size, Elliptic Curve Cryptography (ECC) was utilized in this study for tenant authentication, data encryption, and decryption. The proposed ECC-based authentication technique efficiently defends against many related threats while allowing authorized users access to confidential data. The authors choose the exact and ideal values of elliptic curves to provide more secure data encryption by combining nature-inspired optimizations like the Moth Search Algorithm (MSA) with ECC. The DNS encryption and the ECC encryption technique are combined in the proposed encryption and decryption method. Analysis of the proposed method's security shows that it is effective against certain types of attacks, including denial-of-service attacks, spoofing attacks, reaction attacks, and simple both the selected ciphertext attack and text attacks.

A pairing over an elliptic curve E(F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pm</sub> ) to an extension field of F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pmk</sub> has begun to be attractive in cryptosystems, where k is called the embedding degree. The cryptosystems using a pairing are called the pairing-based cryptosystems. The embedding degree k is also an indicator of the relationship between the elliptic curve discrete logarithm problem (ECDLP) and the discrete logarithm problem (DLP), where ECDLP over E(F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pm</sub> ) is reduced to DLP over F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pmk</sub> . An elliptic curve is determined by j-invarient or order, however the explicit condition between these parameters and an embedding degree has been described only in some degrees. In this paper, we investigate a new condition of the existence of elliptic curves with pre-determined embedding degrees, and present some examples of the elliptic curves over 160-bit, 192-bit and 224-bit F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pm</sub> .

This paper examines the cryptographic security of fixed versus random elliptic curves over the field GF(p). Its basic assumption is that a large precomputation to aid in breaking the elliptic curve discrete logarithm problem (ECDLP) can be made for a fixed curve. We take this into account when examining curve security as well as considering a variation of Pollard's rho method where computations from solutions of previous ECDLPs can be used to solve subsequent ECDLPs on the same curve. We present a lower bound on the expected time to solve such ECDLPs using this method, as well as an approximation of the expected time remaining to solve an ECDLP when a given size of precomputation is available. We conclude that adding 5 bits to the size of a fixed curve to avoid general software attacks and an extra 6 bits to avoid attacks on special moduli and a parameters provides an equivalent level of security.

The reach of algebraic curves in cryptography goes far beyond elliptic curve or public key cryptography yet these other application areas have not been systematically covered in the literature. Addressing this gap, Algebraic Curves in Cryptography explores the rich uses of algebraic curves in a range of cryptographic applications, such as secret sh