Janusz Stoklosa

Involutional Block Cipher for Limited Resources

We propose a scalable block cipher which is an involutional SPN. We use one S-box which is an involution and a bit permutation which also is an involution. As a result we received a totally involutional cipher. It means that we use the same network, and especially the same S-box and the same permutation P in the encryption and decryption data processing. PP-1 is a symmetric block cipher designed for platforms with very limited resources, especially with restricted amount of memory needed to store its components.

Scalable PP-1 block cipher

Scalable PP-1 block cipher A totally involutional, highly scalable PP-1 cipher is proposed, evaluated and discussed. Having very low memory requirements and using only simple and fast arithmetic operations, the cipher is aimed at platforms with limited resources, e.g., smartcards. At the core of the ciphers processing is a carefully designed S-box. The paper discusses in detail all aspects of PP-1 cipher design including S-box construction, permutation and round key scheduling. The quality of the PP-1 cipher is also evaluated with respect to linear cryptanalysis and other attacks. PP-1s concurrent error detection is also discussed. Some processing speed test results are given and compared with those of other ciphers.

The FSR-255 family of hash functions with a variable length of hash result

In the paper a family of cryptographic hash functions with a variable length of hash result, called the FSR-255 family, is presented. The hash functions are defined by some processing structures based on seventeen 15-stage nonlinear feedback shift registers. The feedback functions can be modified by the user to customize the hash function. An algorithm for computing the hash result of length r≤255 is given. It was successfully tested against the birthday attack: no collisions have been found. The FSR-255 family hardware implementation is presented at the level of logical structure. The circuit is designed for implementing as a full custom ASIC, and is optimized to increase the processing rate. The device is capable of working on-line, and can be customized by the user.

Generating Bent Functions

In the paper a method of efficient generation of random bent functions is presented. Obtaining a random bent function is not a straight forward process, since the introduction of bent functions in the most of published works studied their construction and gave algorithms for their generation. Drawing such functions at random from a set of all the Boolean functions is not feasible for n-argument functions for n higher than 4. On the other hand, all the known algorithms for constructing bent functions have deterministic dependencies which introduce certain low complexity problems and significantly narrow the range of bent functions that can be generated with each algorithm (bent function class). We describe a new method of obtaining random bent functions without constraints described above. The algorithm for generating bent functions operates in the Algebraic Normal Form domain. This approach allows for generation of bent functions of arbitrary order and even some special nonlinear requirements as homogeneity.

Evaluation of PP-1 Cipher Resistance against Differential and Linear Cryptanalysis in Comparison to a DES-like Cipher

In the paper we present an involutional block cipher PP-1, which is a scalable SPN. The cipher has very low memory requirements and uses only simple and fast arithmetic operations. The paper discusses in detail the PP-1 cipher design, including the S-box construction, the permutation and the round key scheduling. The quality of the PP-1 cipher is evaluated with respect to differential and linear cryptanalysis. Its quality is compared to the quality of a comparative algorithm with the same block length, as well as to the quality of the class of balanced Feistel ciphers, and in particular to DES quality.

A Cryptographic Mobile Agent Implementing Secure Personal Content Delivery Protocol

This paper describes a proposal of a protocol for secure personal content delivery based on a cryptographic mobile agent. The proposed protocol allows a controlled and secured delivery of personal content (e.g., photo, text message, etc.) to the target device. Furthermore, the protocol is enhanced with time-based constraints in order to impose control over point in time when the content becomes available. The preliminary analysis of the protocol is presented and also some practical applications are discussed. The idea of cryptographic mobile agents is briefly explained to give the reader an understanding of the properties of such agents. The research is based upon leading agent standard, the Foundation for Intelligent Physical Agents, and the protocol is specified using Agent Unified Modeling Language. The paper also describes a prototype of mobile agent implementing the proposed protocol.

Parameterized Hash Functions

In this paper we describe a family of highly parameterized hash functions. This parameterization results in great flexibility between performance and security of the algorithm. The three basic functions, HaF-256, HaF-512 and HaF-1024 constitute this hash function family. Lengths of message digests are 256, 512 and 1024 bits respectively. The paper discusses the details of functions structure. The method used to generate function S-box is also described in detail.

Mobile Agent-Based Digital Rights Management Scheme Implementation

This paper describes an application of cryptographic mobile agents to implement a simple Digital Rights Management (DRM) scheme. The scheme is designed upon a combination of mobile clueless agents, a threshold scheme and one-time passwords. The main goal of the scheme was to make it secure yet lightweight and easy to deploy and to maintain. The scheme is derived from Open Mobile Alliance’s DRM system, which is a leading DRM standard for mobile devices. We describe here the architecture and the implementation of the scheme together with the results of the experiments. The reference implementation was done in Java and tested on JADE agent platform. The experiments were conducted on a distributed system consisting of various machines running different operating systems. We measured the performance of the proposed scheme to assess its usability for real-life applications.

Random Generation of S-Boxes for Block Ciphers

In the paper results of experiments in designing S-boxes and nonlinear Boolean functions as their components are presented. We discuss deterministic algorithms for the construction of bent functions and we formulate our algorithm for random generation of perfect nonlinear functions. We present results of experiments performed on S-boxes and we compare them with results obtained using deterministic methods.