Codebusters C

[KrisZero]

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

Codebusters Wiki

Codebusters Test Exchange 2018

Past Threads: 2018 (Trial), 2019

Past Question Marathons: 2019

[jimmy-bond]

No more easy points for decryption matrices

[Vortexx2]

For the baconian cipher is does it follow the 26 letter alphabet or the 24 letter alphabet (i/j and u/v are the same) or both?

[will0416]

For the baconian cipher is does it follow the 26 letter alphabet or the 24 letter alphabet (i/j and u/v are the same) or both?

At every competition I've been to it's been i/j u/v

[Umaroth]

For the baconian cipher is does it follow the 26 letter alphabet or the 24 letter alphabet (i/j and u/v are the same) or both?

Last year's rules clarifications specified the 24 letter alphabet

[nicholasmaurer]

For the baconian cipher is does it follow the 26 letter alphabet or the 24 letter alphabet (i/j and u/v are the same) or both?

Last year's rules clarifications specified the 24 letter alphabet

Then I guess somebody better tee up a new FAQ :p

[iwonder]

Looking for opinions here, I'm curious what everyone else thinks of the rules. I've always wished they'd lean more towards the cryptography/math intensive problems and shy away from the monoalphabetic tasks (I see them as more repetitive, less thought provoking). Each year so far the rules have moved away from what I'd like though, so I'd love to hear other thoughts on it.

Additionally, wondering what people have seen in regards to the RSA cipher on the higher level exams. I've seen one test that asked for cryptanalysis of RSA based on a weak selection of factors, but nothing else.

[Umaroth]

Looking for opinions here, I'm curious what everyone else thinks of the rules. I've always wished they'd lean more towards the cryptography/math intensive problems and shy away from the monoalphabetic tasks (I see them as more repetitive, less thought provoking). Each year so far the rules have moved away from what I'd like though, so I'd love to hear other thoughts on it.

Additionally, wondering what people have seen in regards to the RSA cipher on the higher level exams. I've seen one test that asked for cryptanalysis of RSA based on a weak selection of factors, but nothing else.

Most of what I've seen of RSA is computation problems with numbers that are far too long to fit into a 4/5-function calculator

[Longivitis]

I like the way that they are going this year with less encryption questions to avoid teams gaining "easy" points. The addition of the pollux and morbit ciphers is good to increase the variety of ciphers (at least it's not as easy as memorizing morse code, although they do give you a table).

Given the variety of aristocrats/patristocrats, I still think teams should study them the most because the other ciphers are simply memorization or pure math.

Hopefully all of the tests use toebes because their formatting is easier to read and create and showing the letter frequencies are nice (looking at you Clements at Cy Falls and UT).

[pepperonipi]

Looking for opinions here, I'm curious what everyone else thinks of the rules. I've always wished they'd lean more towards the cryptography/math intensive problems and shy away from the monoalphabetic tasks (I see them as more repetitive, less thought provoking). Each year so far the rules have moved away from what I'd like though, so I'd love to hear other thoughts on it.

I agree - I wish there were less of an emphasis on the monoalphabetics. All it does is encourage more memorization when this event could have a much greater focus on being able to effectively encrypt/decrypt a variety of cipher types relatively quickly using advanced techniques, such as matrices and modular arithmetic (a good example of this is RSA or the Hill Cipher).