The Lorenz Cipher

Introduction

While Enigma carried army and navy signals, the German high command used a different machine for longer, more secret messages: the Lorenz SZ40/42.

It worked on teleprinter tape. Five bits represented each letter, and two sets of wheels — chi and psi — generated a key stream that was XORed with the message.

Key ideaLorenz was not Enigma. It used 5-bit Baudot code and rotating wheels to XOR a stream of key onto the plaintext.