Nonlinearity

The purpose of this paper is to investigate the relationship between the inflation and inflation uncertainty in Iran. Using mixed models of self-exciting threshold autoregressive (SETAR) and generalized autoregressive conditional heteroskedasticity (GARCH), the inflation behaviors are examined for the period 1990M05-2013M10. This approach allows testing the hypotheses of Friedman-Ball, Pourgerami-Maskus, Cukierman-Meltzer, and Holland during different inflationary regimes. The results indicate that an increase in Iran’s inflation leads to higher inflation uncertainty, as predicted by Friedman-Ball Hypothesis, while the other three hypotheses are not confirmed. Positive unidirectional causality from inflation to uncertainty seems to be significant only in periods of relatively higher inflation, but not in periods of low inflation. The finding is important because it confirms the existence of regime-dependent effect of inflation on public’s expectations about future inflation; that, in trend, it reduces economic activity and misallocates resources. This is a new insight about asymmetric behaviour of inflation in Iran that has noteworthy implications for policy-makers, especially for price stabilizing and inflation targeting. JEL Classifications: C22, E31.

Substitution-boxes (S-boxes) are very important nonlinear components used for achieving strong confusion for enhancing cryptographic security in most of the block ciphers. Designing cryptographically strong S-boxes has been a major research domain for the designers of symmetric crypto systems. In the proposed research work, Bat Algorithm based swarm technique is proposed to design strong S-boxes.  Cryptographic strong S-boxes are obtained by the developed swarm technique. Authors analyze cryptographic strength of the obtained S-box by evaluating properties like Bijectivity, Nonlinearity, Bit-Independence Criterion, Linear Probability and Differential Uniformity. The obtained performance parameters for the designed new S-box by the swarm technique are compared with some recently reported S-boxes in the literature. The designed S-box has good cryptographic strength. The designed S-box has good cryptographic strength like nonlinearity = 110.75 and average Strict Avalanche Criterion (SAC) value = 0.506. For the constructed S-box, most of the Differential uniformity components are 4 and shows uniform distribution approximately. The proposed new S-box is also free from the fixed points.