Security Design Pattern for Login System through Authentication using Modified Sha-384 Algorithm

The research has been carried out to develop secure login system by authenticating the login using modified SHA-384 algorithm. It derives 896-bit hash value for the password entered by the user in the user registration form and saves the credentials entered by the user in system’s database. Results obtained are evaluated by resolving the general attacks confirmed that the modified SHA-384 algorithm was more secured compared to the original SHA-384 algorithm as it was not broken using generic attacks such as brute force, rainbow table and other cracking tools available online such as Cain and Abel. The performance of the modified algorithm was measured with only 2 ms additional execution time from SHA-384.

Tightness of the Suffix Keyed Sponge Bound

Generic attacks are a vital ingredient in the evaluation of the tightness of security proofs. In this paper, we evaluate the tightness of the suffix keyed sponge (SuKS) bound. As its name suggests, SuKS is a sponge-based construction that absorbs the key after absorbing the data, but before producing an output. This absorption of the key can be done via an easy to invert operation, like an XOR, or a hard to invert operation, like a PRF. Using SuKS with a hard to invert absorption provides benefits with respect to its resistance against side-channel attacks, and such a construction is used as part of the authenticated encryption scheme Isap. We derive two key recovery attacks against SuKS with easy to invert key absorption, and a forgery in case of hard to invert key absorption. The attacks closely match the terms in the PRF security bound of SuKS by Dobraunig and Mennink, ToSC 2019(4), and therewith show that these terms are justified, even if the function used to absorb the key is a PRF, and regardless of whether SuKS is used as a PRF or a MAC.

Xoodyak, a lightweight cryptographic scheme

In this paper, we present Xoodyak, a cryptographic primitive that can be used for hashing, encryption, MAC computation and authenticated encryption. Essentially, it is a duplex object extended with an interface that allows absorbing strings of arbitrary length, their encryption and squeezing output of arbitrary length. It inherently hashes the history of all operations in its state, allowing to derive its resistance against generic attacks from that of the full-state keyed duplex. Internally, it uses the Xoodoo[12] permutation that, with its width of 48 bytes, allows for very compact implementations. The choice of 12 rounds justifies a security claim in the hermetic philosophy: It implies that there are no shortcut attacks with higher success probability than generic attacks. The claimed security strength is 128 bits. We illustrate the versatility of Xoodyak by describing a number of use cases, including the ones requested by NIST in the lightweight competition. For those use cases, we translate the relatively detailed security claim that we make for Xoodyak into simple ones.

Analyzing the Linear Keystream Biases in AEGIS

AEGIS is one of the authenticated encryption designs selected for the final portfolio of the CAESAR competition. It combines the AES round function and simple Boolean operations to update its large state and extract a keystream to achieve an excellent software performance. In 2014, Minaud discovered slight biases in the keystream based on linear characteristics. For family member AEGIS-256, these could be exploited to undermine the confidentiality faster than generic attacks, but this still requires very large amounts of data. For final portfolio member AEGIS-128, these attacks are currently less efficient than generic attacks. We propose improved keystream approximations for the AEGIS family, but also prove upper bounds below 2−128 for the squared correlation contribution of any single suitable linear characteristic.

Weak Keys in the Rekeying Paradigm: Application to COMET and mixFeed

In this paper, we study a group of AEAD schemes that use rekeying as a technique to increase efficiency by reducing the state size of the algorithm. We provide a unified model to study the behavior of the keys used in these schemes, called Rekey-and-Chain (RaC). This model helps understand the design of several AEAD schemes. We show generic attacks on these schemes based on the existence of certain types of weak keys. We also show that the borderline between multi-key and single-key analyses of these schemes is not solid and the analysis can be performed independent of the master key, leading sometimes to practical attacks in the multi-key setting. More importantly, the multi-key analysis can be applied in the single key setting, since each message is encrypted with a different key. Consequently, we show gaps in the security analysis of COMET and mixFeed in the single key setting, which led the designers to provide overly optimistic security claims. In the case of COMET, full key recovery can be performed with 264 online queries and 264 offline queries in the single-key setting, or 246 online queries per user and 264 offline queries in the multi-key setting with ∼ 0.5 million users. In the case of mixFeed, we enhance the forgery adversarial advantage in the single-key setting with a factor of 267 compared to what the designers claim. More importantly, our result is just a lower bound of this advantage, since we show that the gap in the analysis of mixFeed depends on properties of the AES Key Schedule that are not well understood and require more cryptanalytic efforts to find a more tight advantage. After reporting these findings, the designers updated their security analyses and accommodated the proposed attacks.

Substitution Attacks against Message Authentication

This work introduces Algorithm Substitution Attacks (ASAs) on message authentication schemes. In light of revelations concerning mass surveillance, ASAs were initially introduced by Bellare, Paterson and Rogaway as a novel attack class against the confidentiality of encryption schemes. Such an attack replaces one or more of the regular scheme algorithms with a subverted version that aims to reveal information to an adversary (engaged in mass surveillance), while remaining undetected by users. While most prior work focused on subverting encryption systems, we study options to subvert symmetric message authentication protocols. In particular we provide powerful generic attacks that apply e.g. to HMAC or Carter–Wegman based schemes, inducing only a negligible implementation overhead. As subverted authentication can act as an enabler for subverted encryption (software updates can be manipulated to include replacements of encryption routines), we consider attacks of the new class highly impactful and dangerous.

Quantum Security Analysis of AES

In this paper we analyze for the first time the post-quantum security of AES. AES is the most popular and widely used block cipher, established as the encryption standard by the NIST in 2001. We consider the secret key setting and, in particular, AES-256, the recommended primitive and one of the few existing ones that aims at providing a post-quantum security of 128 bits. In order to determine the new security margin, i.e., the lowest number of non-attacked rounds in time less than 2128 encryptions, we first provide generalized and quantized versions of the best known cryptanalysis on reduced-round AES, as well as a discussion on attacks that don’t seem to benefit from a significant quantum speed-up. We propose a new framework for structured search that encompasses both the classical and quantum attacks we present, and allows to efficiently compute their complexity. We believe this framework will be useful for future analysis.Our best attack is a quantum Demirci-Selçuk meet-in-the-middle attack. Unexpectedly, using the ideas underlying its design principle also enables us to obtain new, counter-intuitive classical TMD trade-offs. In particular, we can reduce the memory in some attacks against AES-256 and AES-128.One of the building blocks of our attacks is solving efficiently the AES S-Box differential equation, with respect to the quantum cost of a reversible S-Box. We believe that this generic quantum tool will be useful for future quantum differential attacks. Judging by the results obtained so far, AES seems a resistant primitive in the post-quantum world as well as in the classical one, with a bigger security margin with respect to quantum generic attacks.

Functional Graphs and Their Applications in Generic Attacks on Iterated Hash Constructions

We provide a survey about generic attacks on cryptographic hash constructions including hash-based message authentication codes and hash combiners. We look into attacks involving iteratively evaluating identical mappings many times. The functional graph of a random mapping also involves iteratively evaluating the mapping. These attacks essentially exploit properties of the functional graph. We map the utilization space of those properties from numerous proposed known attacks, draw a comparison among classes of attacks about their advantages and limitations. We provide a systematic exposition of concepts of cycles, deep-iterate images, collisions and their roles in cryptanalysis of iterated hash constructions. We identify the inherent relationship between these concepts, such that case-by-case theories about them can be unified into one knowledge system, that is, theories on the functional graph of random mappings. We show that the properties of the cycle search algorithm, the chain evaluation algorithm and the collision search algorithm can be described based on statistic results on the functional graph. Thereby, we can provide different viewpoints to support previous beliefs on individual knowledge. In that, we invite more sophisticated analysis of the functional graph of random mappings and more future exploitations of its properties in cryptanalysis.