Abstract This paper proposes and evaluates a new bipartite post-quantum digital signature protocol based on Winternitz chains and an oracle. Mutually mistrustful Alice and Bob are able to agree and sign a series of documents in a way that makes it impossible (within the assumed security model) to repudiate their signatures. The number of signatures supported by a single public key is still limited, though by a large number. However, the security of the signature scheme is not diminished by repeated application, so when the capacity of a public key is exhausted the last transaction can be used to agree a new key. Some ramifications are discussed, security parameters evaluated and an application area delineated for the proposed concept.

Abstract This paper proposes an architecture and a protocol suite for a permissioned blockchain for a local IoT network. The architecture is based on a sealed Sequencer and a Fog Server running (post-quantum) Guy Fawkes protocols. The blocks of the blockchain are stored in networked Content Addressable Storage alongside any user data and validity proofs. We maintain that a typical IoT device can, despite its resource limitations, use our blockchain protocols directly, without a trusted intermediary. This includes posting and monitoring transactions as well as off-chain (post-quantum) emergency communications without an explicit public key.

Abstract This paper studies known indexing structures from a new point of view: minimisation of data exchange between an IoT device acting as a blockchain client and the blockchain server running a protocol suite that includes two Guy Fawkes protocols, PLS and SLVP. The PLS blockchain is not a cryptocurrency instrument; it is an immutable ledger offering guaranteed non-repudiation to low-power clients without use of public key crypto. The novelty of the situation is in the fact that every PLS client has to obtain a proof of absence in all blocks of the chain to which its counterparty does not contribute, and we show that it is possible without traversing the block’s Merkle tree. We obtain weight statistics of a leaf path on a sparse Merkle tree theoretically, as our ground case. Using the theory we quantify the communication cost of a client interacting with the blockchain. We show that large savings can be achieved by providing a bitmap index of the tree compressed using Tunstall’s method. We further show that even in the case of correlated access, as in two IoT devices posting messages for each other in consecutive blocks, it is possible to prevent compression degradation by re-randomising the IDs using a pseudorandom bijective function. We propose a low-cost function of this kind and evaluate its quality by simulation, using the avalanche criterion.

This poster will present a coordination language for distributed computing and will discuss its application to cluster computing. It will introduce a programming technique of cluster computing whereby application components are completely dissociated from the communication/coordination infrastructure (unlike MPI-style message passing), and there is no shared memory either, whether virtual or physical (unlike Open-MP). Cluster computing is thus presented as something that happens as late as the assembly stage: components are integrated into an application using a new form of network glue: Single-Input, Single-Output (SISO) asynchronous, no deterministic coordination.

We propose weakly-constrained stream and block codes with tunable pattern-dependent statistics and demonstrate that the block code capacity at large block sizes is close to the the prediction obtained from a simple Markov model published earlier. We demonstrate the feasibility of the code by presenting original encoding and decoding algorithms with a complexity log-linear in the block size and with modest table memory requirements. We also show that when such codes are used for mitigation of patterning effects in optical fibre communications, a gain of about 0.5 dB is possible under realistic conditions, at the expense of small redundancy (≈10%).

We propose a two-layered approach for exploiting different forms of concurrency in complex systems: we specify computational components in our functional array language SAC, which exploits data parallel properties of array processing code. The declarative stream processing language S-Net is used to orchestrate the collaborative behaviour of these components in a streaming network. We illustrate our approach by a hybrid implementation of a sudoku puzzle solver as a representative for more complex search problems.

We present information-theory analysis of the tradeoff between bit-error rate improvement and the data-rate loss using skewed channel coding to suppress pattern-dependent errors in digital communications. Without loss of generality, we apply developed general theory to the particular example of a high-speed fiber communication system with a strong patterning effect

Recent work on extracting features of gaps in handwritten text allows a classification of these gaps into inter-word and intra-word classes using suitable classification techniques. In the previous work, we apply 5 different supervised classification algorithms from the machine learning field on both the original gap dataset and the gap dataset with the best features selected using mutual information. In this paper; we improve the classification result with the aid of a set of feature variables of strokes preceding and following each gap. The best classification result attained suggests that the technique we employ is particularly suitable for digital ink manipulation at the level of words.

Recent work on extracting features of gaps in handwritten text allows a classification into inter-word and intra-word classes using suitable classification techniques. In this paper, we apply 5 different supervised classification algorithms from the machine learning field on both the original dataset and a dataset with the best features selected using mutual information. The classifiers are compared by employing McNemar's test. We find that SVMs and MLPs outperform the other classifiers and that preprocessing to select features works well.

A type system with atomic subtyping and a special form of operator overloading, which we call offset-homomorphism is proposed. A set of operator overloadings is said to be offset-homo-morphic when for each pair of overloadings the coercion function realises a homomorphism of types and at the same time certain conditions on the operator type signature are satisfied. We demonstrate that offset-homomorphic overloading has sufficient power for supporting a comprehensive set of array operations in a declarative language. The problem of inferring the least types in our type system is proven to be equivalent to the shortest path problem for weighted, directed graphs with non-negative cycle weights, which has a computationally efficient solution.

This paper describes the principles of an original adaptive interconnect for a computational cluster. Torus topology (2D or 3D) is used as a basis but nodes are allowed to effectively migrate along the torus cycles. An optoelectronic scheme which makes such migrations possible with only local synchronisation is outlined. Between the instances of migration the interconnect behaves as a direct packet routing network which constantly monitors its traffic parameters. A decentralised predictive algorithm is applied periodically to decide whether the current topology is consistent with the predominant traffic flow and if it is not a reconfiguration to a better-matched topology occurs. We present simulation results that show that on some standard computational benchmarks a significant speedup is possible as a result of automatic matching between the effective topology of the application's message passing infrastructure and that of the interconnect.

A comprehensive formalization of data-parallel (DP) symmetries in an imperative language paradigm without nesting is presented, which includes translation, affine and access symmetries. A subtyping system which takes these symmetries into account is discussed. A multi-component type is introduced, with type inclusion in each component reflecting a diminished symmetry of a supertype compared to any of its subtypes. It is possible to use the proposed type scheme in a DP language compiler to deduce access information from unannotated programs.

Received July 1993. revised September 1993.