Data Encryption and Decryption Using Hill Cipher Method and Self Repetitive Matrix

Since times immemorial, security of data to maintain its confidentiality, proper access control, integrity and availability has been a major issue in data communication. As soon as a sensitive message was etched on a clay tablet or written on the royal walls, then it must have been foremost in the sender’s mind that the information should not get intercepted and read by a rival. Codes, hence, form an important part of our history, starting from the paintings of Da Vinci and Michelangelo to the ancient Roman steganographic practices the necessity of data hiding was obvious

Cloud Computing in the Quantum Era

Cloud computing has become the prominent technology of this era. Its elasticity, dynamicity, availability, heterogeneity, and pay as you go pricing model has attracted several companies to migrate their businesses' services into the cloud. This gives them more time to focus solely on their businesses and reduces the management and backup overhead leveraging the flexibility of cloud computing. On the other hand, quantum technology is developing very rapidly. Experts are expecting to get an efficient quantum computer within the next decade. This has a significant impact on several sciences including cryptography, medical research, and other fields. This paper analyses the reciprocal impact of quantum technology on cloud computing and vice versa

Collision Attack on GRINDAHL

Hash functions have been among the most scrutinized cryptographic primitives in the previous decade, mainly due to the cryptanalysis breakthroughs on MD-SHA family and the NIST SHA3 competition that followed. GRINDAHL is a hash function proposed at FSE 2007 that inspired several SHA3 candidates. One of its particularities is that it follows the RIJNDAEL design strategy, with an efficiency comparable to SHA2. This paper provides the first cryptanalytic work on this scheme and we show that the 256-bit version of GRINDAHL is not collision resistant. Our attack uses byte-level truncated differentials and leverages a counterintuitive method (reaching an internal state where all bytes are active) in order to ease the construction of good differential paths. Then, by a careful utilization of the freedom degrees inserted every round, and with a work effort of approximatively $2^{112}$ hash computations, an attacker can generate a collision for the full 256-bit version of GRINDAHL

Finding Bit-Based Division Property for Ciphers with Complex Linear Layers

The bit-based division property (BDP) is the most effective technique for finding integral characteristics of symmetric ciphers. Recently, automatic search tools have become one of the most popular approaches to evaluating the security of designs against many attacks. Constraint-aided automatic tools for the BDP have been applied to many ciphers with simple linear layers like bit-permutation. Constructing models of complex linear layers accurately and efficiently remains hard. A straightforward method proposed by Sun et al. (called the S method), decomposes a complex linear layer into basic operations like COPY and XOR, then models them one by one. However, this method can easily insert invalid division trails into the solution pool, which results in a quicker loss of the balanced property than the cipher itself would. In order to solve this problem, Zhang and Rijmen propose the ZR method to link every valid trail with an invertible sub-matrix of the matrix corresponding to the linear layer, and then generate linear inequalities to represent all the invertible sub-matrices. Unfortunately, the ZR method is only applicable to invertible binary matrices (defined in Definition 3).To avoid generating a huge number of inequalities for all the sub-matrices, we build a new model that only includes that the sub-matrix corresponding to a valid trail should be invertible. The computing scale of our model can be tackled by most of SMT/SAT solvers, which makes our method practical. For applications, we improve the previous BDP for LED and MISTY1. We also give the 7-round BDP results for Camellia with FL/FL−1, which is the longest to date.Furthermore, we remove the restriction of the ZR method that the matrix has to be invertible, which provides more choices for future designs. Thanks to this, we also reproduce 5-round key-dependent integral distinguishers proposed at Crypto 2016 which cannot be obtained by either the S or ZR methods

Rtl Implementation Of Secure Hash Algorithm 3 (Sha-3) Towards Smaller Area

Secure data transfer has been the most challenging task for Internet of Things (IoT) devices. Data integrity must be ensured before and after the data transmission. Cryptographic hash functions are generally the basis of a secure network and used for data integrity verification. Cryptographic hash functions carried out processes such as identity verification, file integrity checking, secure key passing, and source code version control. Among all of the cryptography measures, Secure Hash Algorithm 3 (SHA-3) is the newest and secure cryptographic hash algorithm in the current electronic industry. In the previous Intel Microelectronic SHA-3 design, the synthesized area of the design is large due to many intermediate states and logics of the step mapping functions. The objective of this project is to design a synthesizable SHA-3 with 256-bits hash output and 1600-bits state array with lower area compared to Intel Microelectronic SHA-3. This research implements the SHA-3 in ways such that all the step mapping algorithms are logically combined to only use the input lanes of the state array to eliminate the intermediate logics and reduces the area size. Functionality verification is done using the test case provided by National Institute Standards and Technology (NIST). Two squeezing phases are tested to ensure the functionality of design. Final design of SHA-3 in this research can achieve area reduction by 12.57%, the cell count reduction by 24.35%, the critical path length reduction by 18.84%, and reduction of the clock cycles needed to generate the hash output by 75%. In conclusion, the SHA-3 with smaller area and higher performance has been designed and is possible to cater the needs of IoT application

Dial C for Cipher

We introduce C, a practical provably secure block cipher with a slow key schedule. C is based on the same structure as AES but uses independent random substitution boxes instead of a fixed one. Its key schedule is based on the Blum-Blum-Shub pseudo-random generator, which allows us to prove that all obtained security results are still valid when taking into account the dependencies between the round keys. C is provably secure against several general classes of attacks. Strong evidence is given that it resists an even wider variety of attacks. We also propose a variant of C with simpler substitution boxes which is suitable for most applications, and for which security proofs still hold

Brute Force Cryptanalysis

The topic of this contribution is the cryptanalytic use of spurious keys, i.e. non-target keys returned by exhaustive key search. We show that the counting of spurious keys allows the construction of distinguishing attacks against block ciphers that are generically expected to start working at (marginally) lower computational cost than is required to find the target key by exhaustive search. We further show that if a brute force distinguisher does return a strong distinguishing signal, fairly generic optimizations to random key sampling will in many circumstances render the cost of detecting the signal massively lower than the cost of exhaustive search. We then use our techniques to quantitatively characterize various non-Markov properties of round-reduced Speck32/64. We fully compute, for the first time, the ciphertext pair distribution of 3-round Speck32/64 with one input difference $\Delta$ without any approximations and show that it differs markedly from Markov model predictions; we design a perfect distinguisher for the output distribution induced by the same input difference for 5-round Speck32/64 that is efficient enough to process millions of samples on an ordinary PC in a few days; we design a generic two-block known-plaintext distinguisher against Speck32/64 and show that it achieves 58 percent accuracy against 5-round Speck, equivalent e.g. to a linear distinguisher with $\approx 50$ percent bias. Turning our attention back to differential cryptanalysis, we show that our known-plaintext distinguisher automatically handles the 5-round output distribution induced by input difference $\Delta$ as well as the perfect differential distinguisher, but that no significant additional signal is obtained from knowing the plaintexts. We then apply the known-plaintext brute force distinguisher to 7-round Speck32/64 with fixed input difference $\Delta$, finding that it achieves essentially the same distinguishing advantage as state-of-the-art techniques (neural networks with key averaging). We also show that our techniques can precisely characterize non-Markov properties in longer differential trails for Speck32/64

Attacks on Hash Functions based on Generalized Feistel -- Application to Reduced-Round Lesamnta and Shavite-3-512

International audienceIn this paper we study the strength of two hash functions which are based on Generalized Feistels. We describe a new kind of attack based on a cancellation property in the round function. This new technique allows to efficiently use the degrees of freedom available to attack a hash function. Using the cancellation property, we can avoid the non-linear parts of the round function, at the expense of some freedom degrees. Our attacks are mostly independent of the round function in use, and can be applied to similar hash functions which share the same structure but have different round functions. We start with a 22-round generic attack on the structure of Lesamnta , and adapt it to the actual round function to attack 24-round Lesamnta (the full function has 32 rounds). We follow with an attack on 9-round SHAvite-3 512 which also works for the tweaked version of SHAvite-3 512

Attacks on Hash Functions based on Generalized Feistel - Application to Reduced-Round Lesamnta and SHAvite-3_{512}

In this paper we study the strength of two hash functions which are based on Generalized Feistels. Our proposed attacks themselves are mostly independent of the round function in use, and can be applied to similar hash functions which share the same structure but have different round functions. We start with a 22-round generic attack on the structure of Lesamnta, and adapt it to the actual round function to attack 24-round Lesamnta. We then show a generic integral attack on 20-round Lesamnta (which can be used against the block cipher itself). We follow with an attack on 9-round SHAvite-3_{512} which is the first cryptanalytic result on the hash function (which also works for the tweaked version of SHAvite-3_{512})