Code and data for "From hyperchaotic expansion to stream-cipher failure: observability bounds, finite-precision dynamics and cryptanalysis of a coupled torus map"

Online Resource 1 for the manuscript "From hyperchaotic expansion to stream-cipher failure: observability bounds, finite-precision dynamics and cryptanalysis of a coupled torus map" (submitted to Nonlinear Dynamics). Contents: C and Python source code of the SCUT-4D map (real, integer and floating-point realisations), frozen coupling tables with SHA-256 manifest and test vectors, scripts for Lyapunov spectra, functional graphs and cycle statistics, observability computations, interval-propagation and guess-and-determine state recovery, statistical tests and all figures, together with the raw per-trial results and pinned package versions (requirements.txt). README.md lists the commands that regenerate every number and figure of the manuscript. Scope: the attacks target only the purpose-built SCUT-4D interfaces defined in the manuscript, with deliberately small research parameters; they are not attacks on any other published or deployed scheme.