Towards an auditable cryptographic access control to high-value sensitive data

We discuss the challenge of achieving an auditable key management for cryptographic access control to high-value sensitive data. In such settings it is important to be able to audit the key management process - and in particular to be able to provide verifiable proofs of key generation. The auditable key management has several possible use cases in both civilian and military world. In particular, the new regulations for protection of sensitive personal data, such as GDPR, introduce strict requirements for handling of personal data and apply a very restrictive definition of what can be considered a personal data. Cryptographic access control for personal data has a potential to become extremely important for preserving industrial ability to innovate, while protecting subject's privacy, especially in the context of widely deployed modern monitoring, tracking and profiling capabilities, that are used by both governmental institutions and high-tech companies. However, in general, an encrypted data is still considered as personal under GDPR and therefore cannot be, e.g., stored or processed in a public cloud or distributed ledger. In our work we propose an identity-based cryptographic framework that ensures confidentiality, availability, integrity of data while potentially remaining compliant with the GDPR framework

Using SAT solvers to finding short cycles in cryptographic algorithms

A desirable property of iterated cryptographic algorithms, such as stream ciphers or pseudo-random generators, is the lack of short cycles. Many of the previously mentioned algorithms are based on the use of linear feedback shift registers (LFSR) and nonlinear feedback shift registers (NLFSR) and their combination. It is currently known how to construct LFSR to generate a bit sequence with a maximum period, but there is no such knowledge in the case of NLFSR. The latter would be useful in cryptography application (to have a few taps and relatively low algebraic degree). In this article, we propose a simple method based on the generation of algebraic equations to describe iterated cryptographic algorithms and find their solutions using an SAT solver to exclude short cycles in algorithms such as stream ciphers or nonlinear feedback shift register (NLFSR). Thanks to the use of AIG graphs, it is also possible to fully automate our algorithm, and the results of its operation are comparable to the results obtained by manual generation of equations. We present also the results of experiments in which we successfully found short cycles in the NLFSRs used in KSG, Grain-80, Grain-128 and Grain-128a stream ciphers and also in stream ciphers Bivium and Trivium (without constants used in the initialization step)

Scalable method of searching for full-period Nonlinear Feedback Shift Registers with GPGPU. New List of Maximum Period NLFSRs.

This paper addresses the problem of efficient searching for Nonlinear Feedback Shift Registers (NLFSRs) with a guaranteed full period. The maximum possible period for an $n$-bit NLFSR is $2^n-1$ (all-zero state is omitted). %but omitting all-0 state makes the period $2^n-1$ in their longest cycle of states. A multi-stages hybrid algorithm which utilizes Graphics Processor Units (GPU) power was developed for processing data-parallel throughput computation.Usage of abovementioned algorithm allows to give an extended list of n-bit NLFSR with maximum period for 7 cryptographically applicable types of feedback functions

The search of square m-sequences with maximum period via GPU and CPU

This paper deals with the efficient parallel search of square m-sequences on both modern CPUs and GPUs. The key idea is based on applying particular vector processor instructions with a view to maximizing the advantage of Single Instruction Multiple Data (SIMD) and Single Instruction Multiple Threads (SIMT) execution patterns. The developed implementation was adjusted to testing for the maximum-period of m-sequences of some particular forms. Furthermore, the early abort sieving strategy based on the application of SAT-solvers were presented. With this solution, it is possible to search m-sequences up to degree 32 exhaustively