An Enhanced Visualization Tool for Teaching Monoalphabetic Substitution Cipher Frequency Analysis

Information Systems curricula require on-going and frequent review [2] [11]. Furthermore, such curricula must be flexible because of the fast-paced, dynamic nature of the workplace. Such flexibility can be maintained through modernizing course content or, inclusively, exchanging hardware or software for newer versions. Alternatively, flexibility can arise from incorporating new information into curricula from other disciplines. One field where the pace of change is extremely high is cybersecurity [3]. Students are left with outdated skills when curricula lag behind the pace of change in industry. For example, cryptography is a required learning objective in the DHS/NSA Center of Academic Excellence (CAE) knowledge criteria [1]. However, the overarching curriculum associated with basic ciphers has gone unchanged for decades. Indeed, a general problem in cybersecurity education is that students lack fundamental knowledge in areas such as ciphers [5]. In response, researchers have developed a variety of interactive classroom visualization tools [5] [8] [9]. Such tools visualize the standard approach to frequency analysis of simple substitution ciphers that includes review of most common, single letters in ciphertext. While fundamental ciphers such as the monoalphabetic substitution cipher have not been updated (these are historical ciphers), collective understanding of how humans interact with language has changed. Updated understanding in both English language pedagogy [10] [12] and automated cryptanalysis of substitution ciphers [4] potentially renders the interactive classroom visualization tools incomplete or outdated. Classroom visualization tools are powerful teaching aids, particularly for abstract concepts. Existing research has established that such tools promote an active learning environment that translates to not only effective learning conditions but also higher student retention rates [7]. However, visualization tools require extensive planning and design when used to actively engage students with detailed, specific knowledge units such as ciphers [7] [8]. Accordingly, we propose a heatmap-based frequency analysis visualization solution that (a) incorporates digraph and trigraph language processing norms; (b) and enhances the active learning pedagogy inherent in visualization tools. Preliminary results indicate that study participants take approximately 15% longer to learn the heatmap-based frequency analysis technique compared to traditional frequency analysis but demonstrate a 50% increase in efficacy when tasked with solving simple substitution ciphers. Further, a heatmap-based solution contributes positively to the field insofar as educators have an additional tool to use in the classroom. As well, the heatmap visualization tool may allow researchers to comparatively examine efficacy of visualization tools in the cryptanalysis of mono-alphabetic substitution ciphers.