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Re: Codebusters C

Posted: January 25th, 2019, 6:38 am
by dragonfruit35
I got my test back and realized that they encoded it using a 24-letter alphabet instead of 26 and I am now kicking myself, because the left symbols were A and right symbols were B, which is what I tried initially.
Oh nooooo :cry:

PS: I think this might help you :)

Re: Codebusters C

Posted: January 25th, 2019, 9:23 am
by jimmy-bond
I got my test back and realized that they encoded it using a 24-letter alphabet instead of 26 and I am now kicking myself, because the left symbols were A and right symbols were B, which is what I tried initially.
Oh nooooo :cry:

PS: I think this might help you :)
Thank you. I didn't know that. That might be the reason I mess up on most practice tests.

Re: Codebusters C

Posted: January 30th, 2019, 8:44 am
by Carrot
For solving the timed question, can you get it checked when you still have 1 or 2 errors (as often I can't think of the last word with two missing letters in it) or do you have to fully solve the problem?

Re: Codebusters C

Posted: January 30th, 2019, 10:13 am
by Riptide
For solving the timed question, can you get it checked when you still have 1 or 2 errors (as often I can't think of the last word with two missing letters in it) or do you have to fully solve the problem?
Yes you can have it checked with up to 2 errors.

Re: Codebusters C

Posted: January 31st, 2019, 6:33 am
by mpnobivucyxtz
Is there a standard format for this event? Last year's nationals test provided frequency tables and the Vigenere table as well, but some invitationals I've seen provide neither. What can I expect from regionals and states?

Re: Codebusters C

Posted: January 31st, 2019, 7:23 am
by Longivitis
Is there a standard format for this event? Last year's nationals test provided frequency tables and the Vigenere table as well, but some invitationals I've seen provide neither. What can I expect from regionals and states?
Ideally they should provide the Vigenere table, letters to numbers (A = 0, B = 1), Baconian table, modulo inverse (rarely), and texts for running key ciphers. They should also have frequency percentages for English and Spanish as well.

Re: Codebusters C

Posted: January 31st, 2019, 8:10 am
by jimmy-bond
Is there a standard format for this event? Last year's nationals test provided frequency tables and the Vigenere table as well, but some invitationals I've seen provide neither. What can I expect from regionals and states?
Ideally they should provide the Vigenere table, letters to numbers (A = 0, B = 1), Baconian table, modulo inverse (rarely), and texts for running key ciphers. They should also have frequency percentages for English and Spanish as well.
And unideally, you get nothing and have to do Vigenere the long way, write out the letters to numbers, manually calculate Baconian, and memorize the modulo inverse table as well as frequencies of English and Spanish letters. However this normally only comes up with student-made tests so I wouldn't worry about it at a higher level.

Re: Codebusters C

Posted: January 31st, 2019, 9:58 am
by Riptide
Is there a standard format for this event? Last year's nationals test provided frequency tables and the Vigenere table as well, but some invitationals I've seen provide neither. What can I expect from regionals and states?
Ideally they should provide the Vigenere table, letters to numbers (A = 0, B = 1), Baconian table, modulo inverse (rarely), and texts for running key ciphers. They should also have frequency percentages for English and Spanish as well.
And unideally, you get nothing and have to do Vigenere the long way, write out the letters to numbers, manually calculate Baconian, and memorize the modulo inverse table as well as frequencies of English and Spanish letters. However this normally only comes up with student-made tests so I wouldn't worry about it at a higher level.
I don’t see any reason why event supervisors should provide a baconion table, modulo inverse, or even a letters to numbers table. Kind of takes away any skill gap this event could have for the non mono alphabetic ciphers. I do all the Vigenere by hand because it’s faster for me, but I can understand providing a table for that.

Re: Codebusters C

Posted: January 31st, 2019, 10:27 am
by mpnobivucyxtz
Is there a standard format for this event? Last year's nationals test provided frequency tables and the Vigenere table as well, but some invitationals I've seen provide neither. What can I expect from regionals and states?
Ideally they should provide the Vigenere table, letters to numbers (A = 0, B = 1), Baconian table, modulo inverse (rarely), and texts for running key ciphers. They should also have frequency percentages for English and Spanish as well.
And unideally, you get nothing and have to do Vigenere the long way, write out the letters to numbers, manually calculate Baconian, and memorize the modulo inverse table as well as frequencies of English and Spanish letters. However this normally only comes up with student-made tests so I wouldn't worry about it at a higher level.
For frequencies, I meant the frequency of the letters in a particular ciphertext. Usually seen on tests below the question, where you can fill in the plaintext letters.

Re: Codebusters C

Posted: January 31st, 2019, 6:53 pm
by jimmy-bond
For frequencies, I meant the frequency of the letters in a particular ciphertext. Usually seen on tests below the question, where you can fill in the plaintext letters.
Yeah, they'll usually have that. If they do not provide it, the test maker just hates children