SKSAF: Operationalization of a Seed/Key Security Assessment Framework for Heterogeneous Automotive Diagnostic Environments

The Seed/Key Security Assessment Framework (SKSAF), introduced conceptually in a companion paper, provides a four-phase methodology for evaluating seed/key authentication implementations in automotive OBD diagnostic protocols. This paper presents the full operationalization of SKSAF, with four methodological contributions. The four contributions are: (1) formal statistical procedures for Phase 2 Observable Algorithm-Model Assessment, including an affine function detection test operable on naturally ECU-generated seeds without controlled input, nibble-level uniformity analysis with statistically sound sample size requirements, and normalized Hamming distance autocorrelation for seed sequence correlation analysis; (2) a systematic characterization of five known failure cases of Phase 2 with analytically constructed counterexamples and operational responses for each; (3) detailed protocol test sequences for Phase 3 hardening verification; and (4) an extended set of twelve representative implementation profiles enabling a clean demonstration that the decisive security variable is where the secret resides, not which algorithm computes with it. The framework is executable with commercially available J2534-compliant hardware without specialized laboratory equipment.