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With the development of network technology, cloud computing as an emerging network technology has drawn more and more attention. At the same time, the security and efficiency of cloud computing technology has become major issues restricting the rapid development and popularization of cloud computing technology. By exploring the security of cloud computing service model, this study puts forward the architecture of a service model based on cloud computing. In order to implement the service model safely, a hybrid encryption algorithm is designed to ensure that data cannot be easily stolen during transmission and storage. Besides, this thesis also discusses different implementation mechanisms on data security storage, isolation and backup.

Wireless sensor networks (WSNs) are largely deployed in different sectors and applications, and Elliptic Curve Cryptography (ECC) is proven to be the most feasible PKC for WSN security. ECC is believed to provide same level of security such as RSA with a much shorter key length, and thus they seem to be ideal for applications with small resources such a sensor network, smartcard, RFID, etc. However, like any other cryptographic primitive, ECC implementations are vulnerable to Power Analysis Attacks (PAAs) that may reveal the secret keys by exploiting leaked power consumption from running cryptographic devices (e.g. smart cards, mobile phones etc.). In this paper, we present a comprehensive study of major PAAs and its countermeasures on ECC cryptosystems. In addition, this paper describes critical concerns to be considered in designing PAAs on ECC particular for WSNs, and illustrates the need to conduct, in the near future, intensive researches for the development of these specific PAAs.

While the elliptic curve cryptosystem (ECC) is getting more popular in securing numerous systems, implementations without consideration for side-channel attacks are susceptible to critical information leakage. This paper proposes new power attack countermeasures for ECC over Koblitz curves. Based on some special properties of Koblitz curves, the proposed methods randomize the involved elliptic curve points in a highly regular manner so the resulting scalar multiplication algorithms can defeat the simple power analysis attack and the differential power analysis attack simultaneously. Compared with the previous countermeasures, the new methods are also noticeable in terms of computational cost.

We propose a fast scalar multiplication method using a change-of-basis matrix to prevent power analysis attacks on Koblitz curves. Our method assures the fastest execution time without offline computation compared with previous countermeasures against power analysis attacks. Using the change-of-basis matrix, the Frobenius endomorphism of Koblitz curves is executed in the normal basis representation, whereas point addition is executed in the polynomial basis. In addition, we restrict the range of the number of additions. Even though we do not conceal the number perfectly, the algorithm remains secure with a security parameter chosen carefully. These techniques enable our method to prevent SPA with little computational overhead. For DPA prevention, we introduce randomness with negligible overhead. Timings results show that the proposed method is as efficient as a sliding window method.

We present the first physical side-channel attack on elliptic curve cryptography running on a PC. The attack targets the ECDH public-key encryption algorithm, as implemented in the latest version of GnuPG. By measuring the target's electromagnetic emanations, the attack extracts the secret decryption key within seconds, from a target located in an adjacent room across a wall. The attack utilizes a single carefully chosen ciphertext, and tailored time-frequency signal analysis techniques, to achieve full key extraction.

We present public-key cryptographic protocols for key exchange, digital signatures, and encryption whose security is based on the presumed intractability of solving the principal ideal problem, or equivalently, the distance problem, in the real model of a hyperelliptic curve. Our protocols represent a significant improvement over existing protocols using real hyperelliptic curves. Theoretical analysis and numerical experiments indicate that they are comparable to the imaginary model in terms of efficiency, and hold much more promise for practical applications than previously believed.

We present a novel combined attack against ECC implementations that exploits specially crafted, but valid input points. The core idea is that after fault injection, these points turn into points of very low order. Using side channel information we deduce when the point at infinity occurs during the scalar multiplication, which leaks information about the secret key. In the best case, our attack breaks a simple and differential side channel analysis resistant implementation with input/output point validity and curve parameter checks using a single query.

We present a new side-channel attack path threatening state-of-the-art protected implementations of elliptic curves embedded scalar multiplications. Regular algorithms such as the double-and-add-always and the Montgomery ladder are commonly used to protect the scalar multiplication from simple side-channel analysis. Combining such algorithms with scalar and/or point blinding countermeasures lead to scalar multiplications protected from all known attacks. Scalar randomization, which consists in adding a random multiple of the group order to the scalar value, is a popular countermeasure due to its efficiency. Amongst the several curves defined for usage in elliptic curves products, the most used are those standardized by the NIST. As observed in several previous publications, the modulus, hence the orders, of these curves are sparse, primarily for efficiency reasons. In this paper, we take advantage of this specificity to present new attack paths which combine vertical and horizontal side-channel attacks to recover the entire secret scalar in state-of-the-art protected elliptic curve implementations.

We present a new side-channel attack against VEST, a set of four stream ciphers which reached the second phase of the eSTREAM project (the European stream cipher project). The proposed attacks target the counter part of the ciphers, composed of 16 short-length nonlinear feedback shift registers (NLFSR) independently updated. Our aim is to retrieve the whole initial state of the counter (163 to 173 bits) which is a part of the keyed state. The first attack is directly adapted from previous works on differential side-channel attacks. The second attack is brand new. It involves a unique measurement thus it can be seen as a simple side-channel attack. However, it requires some signal processing so we call it Refined Simple Power Analysis. As we expect full recovery of the initial state with minimal complexity, one should carefully consider implementing any VEST cipher in an embedded device.

We investigate the security of several cryptosystems based on the Chinese remainder theorem (CRT) against side channel attack (SCA). Novak first proposed a simple power analysis against the CRT part using the difference of message modulo p and modulo q. In this paper we apply Novak’s attack to the other CRT-based cryptosystems, namely Multi-Prime RSA, Multi-Exponent RSA, Rabin cryptosystem, and HIME(R) cryptosystem. Novak-type attack is strictly depending how to implement the CRT. We examine the operations related to CRT of these cryptosystems, and show that an extended Novak-type attack is effective on them. Moreover, we present a novel attack called zero-multiplication attack. The attacker tries to guess the secret prime by producing ciphertexts that cause a multiplication with zero during the decryption, which is easily able to be detected by power analysis. We examine the zero-multiplication attack on the above cryptosystems. Finally, we propose countermeasures against these attacks. The proposed countermeasures are based on the ciphertext blinding, but they require no inversion operation. The overhead of the proposed scheme is only about 1% to 5% of the whole decryption.

Various attacks are proposed against different ECDSA implementations: the key-related data are acquired through cache side channels, and then processed to recover the private key. For each cache side channel attack, the requirements of the data qualified for sequent processing vary greatly, and the success probability of private key recovery relies on both the acquired data and the parameters of data processing. So it is difficult to tell, for a certain ECDSA implementation, (a) how many signatures does a cache side channel attack need to recover the private key? or which attack performs the best? and (b) what kind of threat level exists due to potential side channel attacks, if the ECDSA implementation runs for a number of signatures on an unprotected system with cache side channels? Currently, there is no quantitative metric to fairly answer the questions. Such a metric to evaluate cache side channel attacks, will provide a reference for the adversaries to choose the suitable attack, and also for the defenders to set up protections for the certain ECDSA implementation (e.g., updating the private key after it has been used for a certain number of signatures). In this paper, we design an evaluation approach to quantitatively compare the cache side channel attacks against ECDSA. The expected minimum number of signatures needed for at least one successful private key recovery, is proposed as the metric, and this metric considers both the data requirements and the success probability. We apply the approach to evaluate various cache side channel attacks against ECDSA. By calculating the metric, we obtain (a) for each attack, the optimal parameters with the minimum number of signatures needed, and (b) for each ECDSA implementation, the minimum number of signatures that will be enough for at least one successful private key recovery of some cache side channel attacks.

Unprotected implementations of cryptographic primitives are vulnerable to physical attacks. While the adversary only needs to succeed in one out of many attack methods, the designers have to consider all the known attacks, whenever applicable to their system, simultaneously. Thus, keeping an organized, complete and up-to-date table of physical attacks and countermeasures is of paramount importance to system designers. This paper summarises known physical attacks and countermeasures on Elliptic Curve Cryptosystems. For implementers of elliptic curve cryptography, this paper can be used as a road map for countermeasure selection in the early design stages.

To ensure patient’s privacy and protect data exchanged in Telecare Medicine Information Systems (TMIS), several authenticated key agreement schemes were proposed. In this paper, we propose an elliptic curve instantiation of Abdalla and Pointcheval’s Simple Password-Based Encrypted Key Exchange Protocol (SPEKE) including an additional key confirmation step. The proposal is based on short passwords without requiring a complex (PKI). So, it is more suitable to authenticate medical devices and secure medical data exchanged through (RFID) technology, or to ensure remote authenticated key exchanges between patients and servers in TMIS. In addition, we discuss the different security aspects of the proposed protocol, including resistance against side channel attacks in real-world implementations.

This work presents the first differential side channel analysis to exploit photonic emissions. We call this form of analysis Differential Photonic Emission Analysis (DPEA). After identifying a suitable area for the analysis, our system captures photonic emissions from switching transistors and relates them to the program running in the chip. The subsequent differential analysis reveals the secret key. We recovered leakage from the datapath’s driving inverters of a proof of concept AES-128 implementation. We successfully performed DPEA and were able to recover the full AES secret key from the photonic emissions. The system costs for an attack are comparable to power analysis techniques and the presented approach allows for AES key recovery in a relevant amount of time. Thus, this work extends the research on the photonic side channel and emphasizes that the photonic side channel poses a serious threat to modern secure ICs.

This work deals with the energy-efficient, high-speed and high-security implementation of elliptic curve scalar multiplication, elliptic curve Diffie-Hellman (ECDH) key exchange and elliptic curve digital signatures on embedded devices using Four $\mathbb {Q}$ Q and incorporating strong countermeasures to thwart a wide variety of side-channel attacks. First, we set new speed records for constant-time curve-based scalar multiplication, DH key exchange and digital signatures at the 128-bit security level with implementations targeting 8, 16 and 32-bit microcontrollers. For example, our software computes a static ECDH shared secret in $\sim$ ∼ 6.9 million cycles (or 0.86 seconds @8 MHz) on a low-power 8-bit AVR microcontroller which, compared to the fastest Curve25519 and genus-2 Kummer implementations on the same platform, offers 2x and 1.4x speedups, respectively. Similarly, it computes the same operation in $\sim$ ∼ 495 thousand cycles on a 32-bit ARM Cortex-M4 microcontroller, achieving a factor-1.9 speedup when compared to the fastest Curve25519 implementation targeting another Cortex-M4 platform. A similar speed performance is observed in the case of digital signatures. Second, we engineer a set of side-channel countermeasures taking advantage of Four $\mathbb {Q}$ Q 's rich arithmetic and propose a secure implementation that offers protection against a wide range of sophisticated side-channel attacks, including differential power analysis (DPA). Despite the use of strong countermeasures, the experimental results show that our Four $\mathbb {Q}$ Q software is still efficient enough to outperform implementations of Curve25519 that only protect against timing attacks. Finally, we perform a differential power analysis evaluation of our software running on an ARM Cortex-M4, and report that no leakage was detected with up to 10 million traces. These results demonstrate the potential of deploying Four $\mathbb {Q}$ Q on low-power applications such as protocols for the Internet of Things.

This work deals with the energy-efficient, high-speed and high-security implementation of elliptic curve scalar multiplication and elliptic curve Diffie-Hellman (ECDH) key exchange on embedded devices using Four\(\mathbb {Q}\) and incorporating strong countermeasures to thwart a wide variety of side-channel attacks. First, we set new speed records for constant-time curve-based scalar multiplication and DH key exchange at the 128-bit security level with implementations targeting 8, 16 and 32-bit microcontrollers. For example, our software computes a static ECDH shared secret in \(\sim \)6.9 million cycles (or 0.86 s @8 MHz) on a low-power 8-bit AVR microcontroller which, compared to the fastest Curve25519 and genus-2 Kummer implementations on the same platform, offers 2\(\times \) and 1.4\(\times \) speedups, respectively. Similarly, it computes the same operation in \(\sim \)496 thousand cycles on a 32-bit ARM Cortex-M4 microcontroller, achieving a factor-2.9 speedup when compared to the fastest Curve25519 implementation targeting the same platform. Second, we engineer a set of side-channel countermeasures taking advantage of Four\(\mathbb {Q}\)’s rich arithmetic and propose a secure implementation that offers protection against a wide range of sophisticated side-channel attacks. Finally, we perform a differential power analysis evaluation of our software running on an ARM Cortex-M4, and report that no leakage was detected with up to 10 million traces. These results demonstrate the potential of deploying Four\(\mathbb {Q}\) on low-power applications such as protocols for IoT.

This work deals with the design and implementation of pairing based cryptographic hardware and its security analysis against side-channel and fault attacks.

This work addresses the problem of information leakage of cryptographic devices, by using the reconfiguration technique allied to an RNS based arithmetic. The information leaked by circuits, like power consumption, electromagnetic emissions and time to compute may be used to find cryptographic secrets. The results issue of prototyping shows that our coarse grained reconfigurable architecture is robust against power analysis attacks.

This work addresses the problem of hardware attacks against cryptographic circuits. The most dangerous side-channel attack: the differential power analysis (DPA) is discussed, as well the state of art countermeasures. Then new reconfigurable system on chip resistant against DPA attacks is proposed. Results shows that our architecture is efficient against DPA attacks, but also outcomes the performance of classical implementation of modular exponentiation, for key size exceeding 2048 bits, with a reasonable extra area overhead