Author here: Hello 60654, I fully understand the difference between cracking a run length encoding problem and finding weaknesses in DES. There are many tools at the disposal of a security analyst. Another would be CSP and FDR: https://www.google.com.au/url?sa=t&source=web&rct=j&url=http.... However, that article, like mine, goes to show how logic programming can very well be used to mount cryptanalytic attacks. It differs from quantitative statistical methods as these exploit different weaknesses. Qualitative vs quantitative. Most of the people with skills in the latter work in quantitative trading and hedge funds - including yours truly.