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Codebusters C: Teams will cryptanalze (decode) encrypted messages using cryptanalysis techniques and show skill with advanced ciphers by encrypting or decrypting a message.

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Codebusters Test Exchange 2018

Past Threads: 2018 (Trial)

It seems like you can now get points for a question even if you have more than 2 errors (100 points deducted for each error after). How does this work for the first question with the time bonus? If you answer it with lets say 3 errors would it be counted right with a deduction of 100 points or must it be within 2 errors in order it to be counted correct for the bonus?

Riptide wrote:It seems like you can now get points for a question even if you have more than 2 errors (100 points deducted for each error after). How does this work for the first question with the time bonus? If you answer it with lets say 3 errors would it be counted right with a deduction of 100 points or must it be within 2 errors in order it to be counted correct for the bonus?

If the first question is simply numerical, I would refer you to 4.b.iii.

However, if the answer is non-numerical I agree there is ambiguity. I would assume they mean to apply the bonus if you have two or fewer errors (as this would result in full credit). However, an FAQ would be beneficial.

why do codebusters and circuit lab conflict. I am pretty sure that may people do both events

terence.tan wrote:why do codebusters and circuit lab conflict. I am pretty sure that may people do both events

This is the first year that Codebusters is a national event, so there is no sure way of knowing how many people wish to participate in both events.

nicholasmaurer wrote:

Riptide wrote:It seems like you can now get points for a question even if you have more than 2 errors (100 points deducted for each error after). How does this work for the first question with the time bonus? If you answer it with lets say 3 errors would it be counted right with a deduction of 100 points or must it be within 2 errors in order it to be counted correct for the bonus?

If the first question is simply numerical, I would refer you to 4.b.iii.

However, if the answer is non-numerical I agree there is ambiguity. I would assume they mean to apply the bonus if you have two or fewer errors (as this would result in full credit). However, an FAQ would be beneficial.

According to the rules (3.i.i), the timed question is an Aristocrat (mono--alphabetic with spaces) with or without hint. Last year's National trial and I believe the Indiana State trial as well took the timed question at full value if there were less than three errors (see Wisconsin 2018 trial rules, 3.d). In this case nicholasmaurer would be correct.

Since it would not make sense to accept a cryptogram and then deduct "bonus" points, I think that they will look for the same thing this year. Of course, an official clarification would help.

Does anyone have an idea what is expected in the RSA cipher (3.f.iv)? It seems to complicated for encryption or decryption (especially with a 4 function) so what would be tested? I think either a mathematical crypt-analysis or a basic knowledge of how it works might be it.

l0lit wrote:Does anyone have an idea what is expected in the RSA cipher (3.f.iv)? It seems to complicated for encryption or decryption (especially with a 4 function) so what would be tested? I think either a mathematical crypt-analysis or a basic knowledge of how it works might be it.

Yes, it might be fairly complicated as this is a topic reserved for the state/national tournaments. The way I interpret 3.a. I would not expect basic knowledge questions on any CodeBusters exams - everything should be application questions where you are encrypting or decrypting messages using the methods listed in 3.e and 3.f

trdd wrote:Per (f.vi.) at least one of them has to be in Spanish for State and Nationals. So here's an easy standard one in Spanish. It is the first verse of a ridiculous hyperbolic poem: Try to solve it by hand without computers and post how fast you did.
FV QVBF HA QVN PRTNEN GBQN SHRAGR QR YHM, RY HAVIREFB FR NYHZOENEVN PBA RFBF BWBF DHR GVRARF GH.

trdd wrote:This one should be an easy one for anyone out there:
GUVF VF N FGNAQNEQ NAQ PBZZBA EBG GUVEGRRA PNRFNE PVCURE. UBJ DHVPXYL QVQ LBH FBYIR VG JVGUBHG HFVAT BAYVAR ERFBHEPRF?

These should be asked in the question marathon forum.

The preceding posts have been moved to the question marathon.