Variable Bit Permutations: Linear Characteristics and Pure VBP-Based Cipher

Abstract

This paper describes linear characteristics of the variable bit permutations (VBP) that are used in the form of the data-dependent permutations. This primitive suites well to the design of fast cheap-hardware-oriented ciphers. Because of the existence of one characteristic with bias ? we discuss possibility to design a pure VBP-based block ciphers that are indistinguishable from a random transformation. We present design of the cipher which is based only on VBP, fixed permutations, and XOR operations. Performed analysis has shown that the designed pure VBP-based block cipher is secure against differential and linear attacks confirming the efficiency of the VBP as cryptographic primitive.

Keywords

• Variable bit permutations
• data-dependent permutations
• linear analysis
• fast block cipher