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<body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Dear all,<br class=""><br class="">I’m looking for some original information on the famous "Tiltman break" which led to the cryptanalysis of the Lorenz cipher en 1941.<br class="">(<a href="https://en.wikipedia.org/wiki/Cryptanalysis_of_the_Lorenz_cipher" class="">https://en.wikipedia.org/wiki/Cryptanalysis_of_the_Lorenz_cipher</a>)<br class="">(<a href="http://www.eprg.org/computerphile/lorenz-combined.pdf" class="">http://www.eprg.org/computerphile/lorenz-combined.pdf</a>)<div class=""><br class="">The story is: the British intercepted two messages sent with the same key (HQIBPEXEZMUG) also called a "depth".<br class="">When adding the two cipher texts with the exclusive-or function, the key cancels out and what is left is the exclusive-or of the two plain texts.<br class="">From there, brigadier John Tiltman found the two messages by trying various likely pieces of plaintext and found that the first message started with the word SPRUCHNUMMER (message number) and that the second message also used the same word but shortened out as SPRUCHNR.<br class=""><br class="">EVERY SINGLE WEBSITE and the Copeland book "Colossus" list the two intercepted cypher texts as:<br class=""><br class=""><font face="Courier" class="">C1 = JSH5N ZYMFS 01151 VKU1Y U4NCE JEGPB</font><div class=""><font face="Courier" class="">C2 = JSH5N ZYZY5 GLFRG XO5SQ 5DA1J JHD5O</font></div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>and their exclusive-or as:</div><div class=""><br class=""></div><div class=""><font face="Courier" class="">D = ///// //FOU GF14M AQSG5 SEKZR /YWHE<br class=""></font><br class=""></div><div class="">My problem is that IT DOES NOT ADD UP!</div><div class="">The U in 10th position is not the correct result, it should be a V.</div><div class="">(S is 10100, 5 is 11011, so their exclusive-or is 01111 which is V)</div><div class="">And I found other issues with all examples using the cypher text, the messages, the key… I always have several letters which are wrong.</div><div class=""><br class=""></div><div class="">So I’m wondering if I’ve misunderstood something or have the cypher texts been incorrectly written down once and everybody just copied them without checking?</div><div class=""><br class=""></div><div class="">Anybody has genuine information or can point me to some source?</div><div class=""><br class=""></div><div class="">Regards</div><div class="">Emmanuel Lazard</div><div class=""><br class=""></div><div class=""><br class=""></div></div></body></html>