Parallel Collision Search with Cryptanalytic Applications

The concept of public key cryptography was first introduced by Diffie and Hellman in 1976 using discrete logarithm problem as base of difficulty. In 1985, T. ElGamal proposed public key cryptosystem scheme based on discrete logarithm problem. Elliptic curve cryptosystems were first proposed in 1985 independently by Neil Koblitz and Victor Miller. Elliptic curve cryptosystems are unique in using elliptic curve groups for arithmetic. This cryptosystem is based on discrete logarithm problem in the group of points of an elliptic curve defined over a finite field. The discrete logarithm problem in an elliptic curve group appears to be much harder than the discrete logarithm problem in other groups. Hence elliptic curves cryptosystem can match the security of other cryptosystems while using smaller key. In this paper we will discuss a VLSl implementation of elliptic curves cryptosystem for ElGamal encryption scheme.

We show that finding an efficiently computable injective homomorphism from the XTR subgroup into the group of points over GF(p2) of a particular type of supersingular elliptic curve is at least as hard as solving the Diffie–Hellman problem in the XTR subgroup. This provides strong evidence for a negative answer to the question posed by Vanstone and Menezes at the Crypto 2000 Rump Session on the possibility of efficiently inverting the MOV embedding into the XTR subgroup. As a side result we show that the Decision Diffie–Hellman problem in the group of points on this type of supersingular elliptic curves is efficiently computable, which provides an example of a group where the Decision Diffie–Hellman problem is simple, while the Diffie–Hellman and discrete logarithm problems are presumably not. So-called distortion maps on groups of points on elliptic curves that play an important role in our cryptanalysis also lead to cryptographic applications of independent interest. These applications are an improvement of Joux’s one round protocol for tripartite Diffie–Hellman key exchange and a non-refutable digital signature scheme that supports escrowable encryption. We also discuss the applicability of our methods to general elliptic curves defined over finite fields which includes a classification of elliptic curve groups where distortion maps exist.

We discuss analogs based on elliptic curves over finite fields of public key cryptosystems which use the multiplicative group of a finite field. These elliptic curve cryptosystems may be more secure, because the analog of the discrete logarithm problem on elliptic curves is likely to be harder than the classical discrete logarithm problem, especially over ${\text {GF}}({2^n})$. We discuss the question of primitive points on an elliptic curve modulo p, and give a theorem on nonsmoothness of the order of the cyclic subgroup generated by a global point.

Elliptic curve cryptosystem (ECC) was proposed by Miller [10] and Koblitz [9] which relies on the difficulty of elliptic curve discrete logarithmic problem (ECDLP). It is gaining wide acceptance as an alternative to the conventional public key cryptosystem such as RSA [24], DSA [25], DH [26]. Also it is noted that the wireless sensor networks (WSN) based on the rapid progress of wireless communications and embedded micro electro mechanical systems technologies are becoming important part in our daily life. The security of the WSN becomes one of the major concerns in its applications. Even ECC prominently offers great potential benefits for WSN security there is still a lot of work needs to be done due to WSN has very restraint running conditions such as limited energy source, capability of computing, etc. It is well known that scalar multiplication operation in ECC accounts for about 80% of key calculation time on wireless sensor network motes. In this paper we present an optimized dynamic window based on our previous research works. The whole quality of service (QoS) has been improved under this algorism in particularly the power consuming is more efficiently. The simulation results showed that the average calculation time, due to fuzzy conditions decreased from previous 26 to current 9 as a whole the calculation time, decreased by approximately 18% in comparison to our previous algorithms in an ECC wireless sensor network [23].

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

Digital Images for seamless transmission over mobile network are required to be ensured with authentication and increasing concern for their integrity, originality and non repudiation qualities. In this paper, a novel approach of digital signature scheme of an image is introduced. The proposed scheme consists of three main steps. First, pixel selection, second, pixel values digest through hash function, and finally, creation of digital signature using elliptic curve cryptography based on public key cryptosystem. In this process, the sender uses the private key for hash value encryption, and the recipient uses the public key for signature verification. Instead of directly sending an original image to the recipients, the embedded copy is sent with signed digital signature for authentication.

Recently, various user authentication schemes have successfully drawn researchers' attention and been studied widely in order to guarantee secure communication for wireless sensor networks (WSNs). This paper proposes a new biometric-based authenticated key agreement scheme using Elliptic Curve Cryptosystem (ECC) for WSN to minimize the complexity of computational costs between the sensor node and the GW-node and fit low-power sensor network environments. Compared with previous schemes, the newly proposed scheme has the following more practical characteristics: (1) it provides secure session key agreement function by adopting elliptic curve cryptosystem, (2) it can reduce the total execution time and memory requirement due to the elliptic curve cryptography, (3) it is not only secure against well-known cryptographical attacks but also provides perfect forward secrecy, and (4) it does not require the user password and uses only hash function. Analysis results show that the proposed scheme is extremely suitable for use in WSNs since it provides security, reliability, and efficiency.

In this paper, we propose a secure two-factor remote user authentication protocol using Elliptic curve cryptography. The proposed protocol provides the mutual authentication of participants, session key agreement and user anonymity. The security of our proposed protocol is based on one way hash function and elliptic curve cryptosystem and it is secure against all relevant security attacks. Compared with other relevant protocol, the security analysis and performance evaluation show that our proposed protocol can provide high level of security with less communication and computation cost. In addition, the BAN logic is applied to demonstrate the validity of the proposed protocol.

In this digital world, communication systems have witnessed abundant usage of media over the platforms. Among these, providing security in transmission of images is highly important, and attained a lot of research interest due to its high consideration in both the industry and the academic community. This paper proposes a hybrid asymmetric image encryption algorithm using Elliptic curve cryptosystem (ECC), Hadamard transform and Hill cipher algorithms. Based on the Diffie–Hellman public key exchange method a point on the elliptic curve is selected and agreed between both the sender and receiver. The key relies upon the ECC and it is difficult to resolve the ECDLP to get it. The proposed algorithm involves two stages of encryption, primarily, the XOR function is applied on the Elliptic curve Diffie-Hellman (ECDH) shared secret key and the hadamard image. In the subsequent stage, ECC is combined with the hill cipher algorithm. Encryption and decryption uses self-invertible key matrix, hence the process of finding inverse key becomes redundant during decryption which improves the speed of execution. It also enhances the security and efficiency compared to original hill cipher method. The results are compared with other ECC methods proves that the current cryptosystem attains large key space, highly key sensitive, low correlation and can resist against differential and statistical attacks.

Recently, a fast and secure hash function SFHA - 256 has been proposed and claimed as more secure and as having a better performance than the SHA - 256. In this paper an improved version of SFHA - 256 is proposed and analyzed using two parameters, namely the avalanche effect and uniform deviation. The experimental results and further analysis ensures the performance of the newly proposed and improved SFHA-256. From the analysis it can be concluded that the newly proposed algorithm is more secure, efficient, and practical.

The acceleration of cryptographic applications on embedded devices is a topic of increasingly importance, due to their massive use. In this paper, the efficiency of these devices when operating as cryptographic accelerators is assessed, using a two-tiered parallelism model, where not only multi-core, but also Single Instruction Multiple Data (SIMD) parallelism is exploited to increase the throughput of modular multiplications. In addition, the applicability of the developed parallel modular multiplications are tested for the Rivest-Shavir-Adleman (RSA) and Elliptic Curve (EC) cryptosystems. The relative efficiency of the two-tiered model for implementing cryptosystems on general purpose processors and embedded devices is analysed and experimentally evaluated. It can be concluded that it is possible to achieve the same levels of execution enhancement on both platforms. Moreover, speedups of up to 7.3 and 3.9 are obtained for the RSA and EC cryptosystems on the ARM A15 quad-core processor, respectively.

Elliptic curve cryptosystem — The answer to strong, fast public-key cryptography for securing constrained environments

Since their invention in the mid 1980s, Elliptic Curve Cryptosystems (ECC) have become an alternative to common Public-Key (PK) cryptosystems such as, e.g., RSA. The utilization of Elliptic Curves (EC) in cryptography is very promising because of their resistance against powerful index-calculus attacks. Providing a similar level of security as RSA, ECC allows for efficient implementation due to a significantly smaller bit size of the operands. It is widely accepted that the only feasible way to attack actual cryptosystems, if at all, is the application of dedicated hardware. In times of continuous technological improvements and increasing computing power, the question of the security of ECC against attacks based on special-purpose hardware and, in particular based on recently emerged low-cost FPGAs, arises.This work presents the first architecture with a corresponding FPGA implementation of an attack against ECC over prime fields. We describe an FPGA-based multi-processing hardware architecture for the Pollard-Rho method which is, to our knowledge, currently the most efficient attack against ECC. The implementation is running on a contemporary low-cost FPGA which allows for a much better cost-performance ratio than conventional CPUs. With the implementation at hand, a fairly accurate estimate about the cost of an FPGA-based attack can be given. We will extrapolate the results on actual ECC key lengths (128 bits and above) and estimate the expected runtimes for a successful attack. Since FPGA-based attacks are out of reach for key lengths exceeding 128 bits, we provide estimates for an ASIC design.Based on our results, currently used elliptic curve cryptosystems (160 bit and above) are infeasible to break with available computational and financial resources. However, some of the security standards proposed by the SECG in [2, 3] become subject to attacks based on low-cost FPGAs.

In this paper we present a comparative performance analysis of nine blind signature schemes that have been proposed since 1983 until 2008, spanning a total of 25 years of active research in this topic. We give a short description of all the schemes studied and their main components. This includes customary arithmetic building blocks such as modular exponentiation, elliptic curve scalar multiplication, bilinear pairing computation and a special hash function that maps arbitrary input strings to elliptic curve points (the so-called map-to-point hash function). We developed a C language library that implements all the nine schemes selected and then conducted timing tests on a Pentium IV processor working at 2.0 GHz, which allow us to report a software performance comparison of those methods when using a cryptographic strength equivalent to 80 security bits.

An elliptic curve cryptosystem (ECC) is one of public key cryptosystem, whose security is based on elliptic curve discrete logarithm problem (ECDLP). An elliptic curve is uniquely determined by mathematical parameters such as j-invariant of an elliptic curve. By giving trace of elliptic curve, t, a definition field \(\mathbb F_{p}\), and discriminant D, an elliptic curve with order \(\sharp {E(\mathbb F_{p})} = n\) is determined. Therefore it is an open problem to determine explicit relations between the mathematical parameters and the embedding degrees k. Hirasawa and Miyaji presented concrete relations between the mathematical parameters and the embedding degrees. In this research, a new explicit relation between elliptic-curve parameters and embedding degrees is investigated by generalizing their research.