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### Re: Codebusters C

Posted: October 4th, 2018, 6:47 pm
Do you have to be extremely good at math for this event?
Not for most ciphers. There are a few that require significant math background (e.g. Hill cipher).
Most ciphers just require studying and memorization. Make sure you know your alphabet very well. As Unome said only a few require actual number crunching.

### Re: Codebusters C

Posted: October 5th, 2018, 4:00 pm
Can someone do a quick walkthrough on how to solve an RSA cipher?

### Re: Codebusters C

Posted: October 5th, 2018, 4:31 pm
Can someone do a quick walkthrough on how to solve an RSA cipher?
Does this help?

### Re: Codebusters C

Posted: October 6th, 2018, 12:24 pm
Can someone do a quick walkthrough on how to solve an RSA cipher?
Does this help?
Ah yes, thank you so much!

### Re: Codebusters C

Posted: October 6th, 2018, 1:53 pm
Can someone do a quick walkthrough on how to solve an RSA cipher?
Does this help?
Ah yes, thank you so much!
Just make sure you know encryption and decryption

### Re: Codebusters C

Posted: October 16th, 2018, 8:36 am
Any tips on solving monoalphabetic ciphers?

Also, can you get a good score without a team member who knows Spanish?

### Re: Codebusters C

Posted: October 16th, 2018, 9:23 am
Any tips on solving monoalphabetic ciphers?

Also, can you get a good score without a team member who knows Spanish?

I still need to work on monoalphabetic, but as far as I can tell word patterns are really useful. For example being able to recognize something like xaxybcdxyx as everywhere forms a good basis to work off of.

### Re: Codebusters C

Posted: October 16th, 2018, 11:56 am
Any tips on solving monoalphabetic ciphers?

Also, can you get a good score without a team member who knows Spanish?
Keep an eye out for common words. Frequently appearing three-letter words are commonly "the" or "and", so trying to figure those out can be a good starting point. Single-letter words are really nice since they're almost always "a" or "I" (could technically be "O' I guess if it's a poem or something, but that's rare).

Also keep in mind what the most frequent letters in the alphabet are. If you see a letter appearing frequently, it's likely to be E T A O I N or S, which are some of the most common letters. It's probably not Q X J or Z, haha.

According to the rules, "no more than one" puzzle can be in Spanish for Regionals or Invitationals, so that's likely a pretty small portion of your score, if it appears at all. For States, I think it's "at least one" so that becomes much more important, but I would imagine that the question itself is a bit easier to compensate for the fact that it's in a Spanish. I guess if you really practice, you could probably do reasonably well even without knowing Spanish as long as you know the rules of the language. In the end, I doubt it's going to be a killer, though I suppose that might be what separates the very top teams at States and Nationals.

### Re: Codebusters C

Posted: October 18th, 2018, 1:16 pm
Letters can't replace themselves in the key for substitutions right? For example, E -> E.

### Re: Codebusters C

Posted: October 18th, 2018, 1:35 pm
Letters can't replace themselves in the key for substitutions right? For example, E -> E.
The rules say that in the aristocrats, patristocrats, and xenocrypts, letters can not encrypt to themselves, so yes that can not happen in the ciphers mentioned earlier.