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Post by mauser on May 7, 2017 5:11:08 GMT
Ok, so I've had a chance to decode several messages and have communicated with at least two of you at this point. But I have a question regarding the message encryption procedures that are published. For the M4 4-rotor messages, a single trigram is entered into the machine with the wheels set for ground. The result is entered into the steppable wheel and the greek wheel is left as it was in the ground setting. Every thing I've read and even mentioned in Dirk's procedures indicate that the complete Verfahrenkengruppe quadram is encoded, resulting in a full 4 character message key. This is significantly more cryptographically secure than using a trigram only on a machine capable of setting 4 wheels. Is there any reason this group has chosen to go with just a trigram versus the full quadram which is historically accurate?
A noob is asking. Thanks!
Mauser sends
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Post by lpaseen on May 7, 2017 16:52:40 GMT
Ok, so I've had a chance to decode several messages and have communicated with at least two of you at this point. But I have a question regarding the message encryption procedures that are published. For the M4 4-rotor messages, a single trigram is entered into the machine with the wheels set for ground. The result is entered into the steppable wheel and the greek wheel is left as it was in the ground setting. Every thing I've read and even mentioned in Dirk's procedures indicate that the complete Verfahrenkengruppe quadram is encoded, resulting in a full 4 character message key. This is significantly more cryptographically secure than using a trigram only on a machine capable of setting 4 wheels. Is there any reason this group has chosen to go with just a trigram versus the full quadram which is historically accurate? A noob is asking. Thanks! Mauser sends I do not disagree with you, I also read that all 4 letters are to be used at Dirks site and I think some other place but I'm not the founder of this forum and since this forum is tightly connected to enigmaworldcodegroup.com (same founders I think) I did choose to use the procedure published there (https://www.enigmaworldcodegroup.com/encypting-kriegsmarine). As for fact check, I have not seen a original triton procedure manual used after feb 2 1942 (when 4 wheels started to be used), only written procedures here and there so which one that is correct I can not say that easily. I also haven't seen any info on how the bigram tables are used, how often they where changed and so on so what I put in this forum is a guess and procedure to not add to much pain in (d)encypt messages. In reality I think it was several bigram tables and which one was used depended on the day or week or something, and they where of course replaced now and then during the year. As for security - doesn't matter to much in this forum since codebooks are published also.
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Post by mauser on May 9, 2017 10:32:48 GMT
My understanding of the bigram tables there were nine, but like you, no information as to how often if at all they were changed. I've created a bigram book that uses 26 tables, and then a set of Tauschtafelplan tables to choose which bigram table to use on a certain day in a month. The tables cover the entire year. I did take some liberties with my K book. Here I have 10920 quadrams divided into 420 quads per table. It simply saves picking the random characters.
Understand about security in that the codes are published. However, I am thinking in terms of historical accuracy. I'm also interested in research to find combinations in historical machines that would have ramped up the security of those machines, provided of course the operators followed instructions. For instance, the M4 had a B and C thin reflector and the Beta and Gamma wheels. These never moved so in essence you had a three wheel Enigma and the reflector and thin wheel combination became a reflector. With two and two and 26 setting per wheel, the M4 boosted the number of 'reflectors' to 456,976. But throw in a third reflector, the UKW-D and not rewire it regularly. That add alone boosts the number of theoretical reflectors to 308,915,776! The other thing I have in my key sheet generator is to create 11 plug pairs instead of the usual 10. That's 20+ trillion more permutations. One theoretical version I'm considering is an M4 with all 4 wheels steppable, and three reflectors. A blend of the M4 and the last version of the 'G'.
Anyway, those are all theoretical designs, and someday I'll have some of my friends interested enough to trade message traffic to test them. My S&T Geotronics Enigma can currently do the M4, M3, and the Enigma G, versions, Ch.A, Ch.B, and Ch.C. My codesheet generator can build tables for these versions as well.
Well, enough long winded reply to a reply. Having fun in this forum, hope to have more.
Mauser sends
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