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Security efficiency and hardware efficiency are equally important when designing a block cipher. In this paper, we propose a new block cipher that uses string transformations and requires less memory and fewer computational resources, making it suitable for highly constrained environments. We compare the performance of our design with AES-128 and quasigroup-based block cipher INRU in the cipher block chaining (CBC) mode of operation using the National Institute of Standards and Technology (NIST) test suite. We then analyze our design against the standard linear, differential, and algebraic attacks. Choosing suitable S-boxes and a quasigroup of a smaller order does not compromise the security of the cipher, but the storage space is reduced compared with AES-128 and INRU. [ABSTRACT FROM AUTHOR]

In this paper, we present a new test for stream ciphers named the 'Bit Inclusion Test (BIT)'. This test provides an enhancement to the conventional avalanche test for stream ciphers. This test is efficient and includes the conventional avalanche test. Additionally, it can capture the shortcomings which escape the conventional avalanche test. We also demonstrate, with examples, how BIT is capable of going deeper into the structure of crypto-algorithms and detecting internal biases which make an algorithm susceptible to cryptanalytic attacks. [ABSTRACT FROM AUTHOR]

'Rotation and shift' based diffusion functions are used in modern ciphers especially in ARX (Addition, Rotation, and XOR) based designs. They are preferred over other alternatives as they are efficient and lightweight. Usually, such diffusion functions map an n-bit block to another n-bit block. One of the requirements for an n-bit to n-bit diffusion function is that, it should be invertible. In this paper, we present mathematical models for different classes of 'rotation and shift' based diffusion functions and explore their invertibility. We derive sufficient conditions under which diffusion functions of these classes are invertible. [ABSTRACT FROM AUTHOR]

The security of block ciphers solely depends on the S-boxes used in their design. Hence, for a secure block cipher, S-boxes should be chosen very thoughtfully. n-ary quasigroups of different orders and for different values of n are being used to design various cryptographic primitives. In the literature, many algorithms based on the quasigroups have been proposed for the generation of S-boxes of order 4. However, in this article, we propose a general method for the construction of symmetric S-boxes of even order using ternary quasigroups of order 4 with certain properties. These S-boxes give strong resistance against linear, differential, algebraic, and DPA attacks and hence provide good cryptographic properties. [ABSTRACT FROM AUTHOR]

The period of a binary sequence generated by feedback with carry shift register (FCSR) depends on the connection integer (q) of the register. We define FCSR primes as primes generating maximum possible period sequences when used as connection integer of an FCSR. Hence, to design good FCSR pseudorandom generators, one needs suitable feedback primes. The authors of this article study some properties about these primes and give algorithms to generate some of them. The first algorithm is somewhat straightforward and is based on the criterion given in Arnault and Berger. We propose two new algorithms for the efficient generation of FCSR primes. Comparison between these algorithms, supported by experimental and analytical results is presented. Further, we address the question of quantification of such primes and derive some explicit bounds. [ABSTRACT FROM AUTHOR]

GOST-R 34.11-94 is a Russian standard cryptographic hash function that was introduced in 1994 by the Russian Federal Agency for the purposes of information processing, information security, and digital signature. Mendel et al. (2008) and Courtois and Mourouzis (2011) found attacks on the compression function of the GOST-R structure that were basically weaknesses of the GOST-R block cipher (GOST 28147–89, 1989). Hence in 2012, it was updated to GOST-R 34.11-2012, which replaced the older one for all its applications from January 2013. GOST-R 34.11-2012 is based on a modified Merkle-Damgård construction. Here we present a modified version of GOST-R 34.11-2012 (Modified GOST-R (MGR) hash). The design of the MGR hash is based on wide-pipe construction, which is also a modified Merkle-Damgård construction. MGR is much more secure as well as three times faster than GOST-R 34.11-2012. Advanced Encryption Standard (AES)-like block ciphers have been used in designing the compression function of MGR because AES is one of the most efficient and secure block ciphers and has been evaluated for more than 14 years. A detailed statistical analysis with a few other attacks on MGR is incorporated into this paper. [ABSTRACT FROM AUTHOR]

Cryptographic properties of permutations viz non-linearity, affine equivalence, and mode transform have been studied in the literature, treating them as bijections on ℤn. In this article, the authors consider them as bijection on an arbitrary finite commutative ring with unity. Treating them this way, they achieve a generalization of the above mentioned properties. The authors also propose an algorithm for computing non-linearity in their generalized scenario, which is faster compared to the direct approach in many cases. [ABSTRACT FROM PUBLISHER]

Momordica dioica is an important summer vegetable crop in India and is dioecious. DNA bulks of six male and six female accessions of M. dioica were subjected to random amplified polymorphic DNA (RAPD) marker analysis using 40 primers, of which 22 primers responded for amplification. Of these, ten primers generated reproduction type-specific amplification of DNA fragments at the bulk level. This number was reduced to three RAPD primers when re-tested, individually, with six male and six female accessions. One random decamer primer, OPA-01, produced two unique amplified fragments in all female plants, while two other primers, OPB-04 and OPC-08, generated distinct amplified fragments in both male and female plants. Three amplified fragments (OPB-04430, OPC-081135, and OPC-08578) were unique to all six male accessions, while five amplified fragments (OPA-011560, OPA-01880, OPB-04880, OPB-04800, and OPC-081230) appeared uniquely and uniformly in all six female accessions. Southern hybridisation analysis was performed using five of these sex-specific amplified fragments (OPA-01880, OPB-04880, OPB-04430, OPC-08578, and OPC-081230) as probes with Eco RI and Hind III double-digested DNA of all male and female accessions. Southern hybridisation analysis with the OPC-08578 probe showed a unique hybridisation pattern for all six male accessions, as with the respective RAPD marker, whereas the other probes showed complex hybridisation patterns. Further, inheritance studies also confirmed the presence of a homologous restriction fragment targeted by this probe in F1 progenies, as expected. Hence, OPC-08578 could be used as a marker to ascertain the sex of M. dioica plants at an early stage of development. [ABSTRACT FROM AUTHOR]

The objective of the present investigation was to study the spontaneous self-assembling behavior of stearic acid in the presence of its monoglyceride and to evaluate its potential to be used as drug delivery vehicle. The interesting feature of this system lies in spontaneous formation of vesicles on hydration of molten mixture of stearic acid (SA) and glyceryl monostearate (GMS) without using any solvent. The 1H NMR spectrum of a sample was devoid of signals from fatty acid side chain protons, suggesting that upon interaction between SA and GMS, it adopts an orientation in which fatty acid side chains exists in hydrophobic domains separated from hydrophilic headgroup. A single endothermic event of optimized formulation was obtained as the inflection point of the jump heat capacity at 57°C. To evaluate its feasibility to be used as drug delivery vehicle, ciprofloxacin HCl (CFn) was chosen as a model drug. The entrapment efficiency of CFn was found to be 13 ± 3% and 32 ± 4.2% when the formulation was prepared at pH 5.5 and 9.5, respectively. When viewed through polarizing filter, discernible Maltese cross was observed describing bilayer structure. The viscosity profile demonstrates that the both of the formulation follow Newtonian flow. The size of the vesicles was found to be in the range of 1-3 µm. In a 24 hours study period the VES-1c and VES-2c formulation released 95.8% and 82.3% of the drug, respectively. The formulation was found to be resistant towards osmotic stress. These formulations were found to be biocompatible when studied against J774 macrophages. [ABSTRACT FROM AUTHOR]

The main purpose of the present study was to investigate different cationic submicron emulsions as potential delivery for oral administration. Different submicron emulsion based formulations were prepared by standard procedures incorporating Chitosan, stearylamine, and protamine as charge inducer. Saquinavir (SQ) laden emulsions were characterized in terms of globule size, zeta potential, entrapment efficiency, release profile, cytotoxicity, LDH release, and stability studies. The prepared formulations were stable in terms of mean globule size, drug content, and tended to retain their cationic charge. Pay load efficiency was found to be pretty high (≈ 95–99%) in various formulations prepared. Sustained release phenomenon was more prominent in the case of chitosan emulsions (CE) followed by stearylamine emulsion (SE), Protamine emulsion (PE), and then plain emulsion (E) containing no charge inducer. The total amounts of drug released in 24 hr from CE, SE, PE, and E were 46%, 52%, 56%, and 62%, respectively. The induction of positive charge in emulsions resulted in enhanced absorption of drug through intestinal membrane. The apparent permeability coefficient through the intestinal sac was in the order of CE > SE > PE > E. The permeation flux of SQ through CE (1.0 μg/min) was more than twice compared to plain emulsion (0.46 μg/min) while it was almost three times (0.3 μg/min) compared to control. However, protamine based emulsion didn’t confer significant improvement in absorption when compared to plain emulsion formulation. By this study it can be concluded that induction of positive charge on submicron emulsions can be effective for improving oral absorption of drug safely, as it is evinced with low LDH release into the medium when intestinal tissue is treated with submicron emulsion. [ABSTRACT FROM AUTHOR]

Low entrapment of drugs into liposomes is a serious challenge in their commercial application. 6-Mercaptopurine (6-MP), an antineoplastic agent, is such a drug with low entrapment efficiency (EE). We devised their lipophilic derivatization as a means of enhancing EE by covalently coupling 6-MP with glyceryl monostearate (GMS) via a succinic anhydride spacer. This prodrug had an improved partition coefficient value of 25.16 compared to 1.22 for free drug, confirming higher lipophilicity. A hydrolysis rate study of prodrug indicated 2.90%, 12.5%, 24.1%, and 25.1% hydrolysis in phosphate buffered saline (PBS) (pH 7.4) and 10%, 20%, and 30% serum, respectively. Liposomes of phosphatidylcholine (PC)/sphingomyelin, cholesterol, and dicetyl phosphate bearing drug or prodrug were prepared by shaking by hand and sonication methods. The EE was found to increase from 1.92% for free drug to 91.8% for drug-conjugate. An in vitro cell line toxicity study on L1210 leukemia cells showed improved performance of liposome-encapsulated drug-conjugate compared to free drug. The plasma drug level profile following administration of free drug and the liposomal formulation containing prodrug (HE liposome) manifested a higher sustained level of the latter, which was further improved in case of sphingomyelin-containing liposomes (STHE liposome). The pharmacokinetic parameters revealed an increase in half-life, from 61 min to 120 min for the HE liposomes and 296 min for the STHE liposomes. Therefore, increased entrapment was made possible through lipophilic derivatization, and it was subsequently tested in vivo. [ABSTRACT FROM AUTHOR]

A new derivative of erythrocyte ghosts - reverse biomembrane vesicles (RBVs) - was developed, loaded with doxorubicin HCl (Dox RBVs), and extensively characterized both in vivo and in vitro. The formulation of reverse biomembrane is based on budding of membrane into the ghost interiors (endocytosis) leading to accumulation of small vesicles within each parent ghost. The system was evaluated in vitro for entrapment efficiency, membrane orientation, vesicle size, release profile, and centrifugal stress. The stability studies were performed at 4°C by assessing the effect on vesicle size and leakage after 7, 15, and 21 days. The stability study showed negligible leakage and no appreciable change in vesicle size after storage for several days-an indication of good stability of RBVs formulation. The formulation and process variables were optimized to obtain vesicles of 1.2-1.8 μm. The amount of doxorubicin entrapped in RBVs was 0.75 mg/ml of packed vesicles. The in vitro release profile showed 52.86% of drug release in 16 hr. A membrane orientation study revealed inversion of membrane surface because only 10% of sialic acid was accessible on trypsin treatment. The plasma clearance data revealed an increase in halflife and bioavailability of drug. Tissue concentration data suggest that liver and spleen remain the major organs for clearance of these drug-loaded RBVs, which suggests preferential uptake by the reticuloendothelial system. On the whole, this vesicle system proved to be of potential application in cancer chemotherapy. [ABSTRACT FROM AUTHOR]