Codebusters C

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Umaroth
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Re: Codebusters C

Post by Umaroth »

Since it isn't specified in the rules, does anyone know how test writers unwittingly giving us non invertible Hill cipher matrices will be prevented? This would probably cause a lot of frustration among teams.
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Re: Codebusters C

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Umaroth wrote:Since it isn't specified in the rules, does anyone know how test writers unwittingly giving us non invertible Hill cipher matrices will be prevented? This would probably cause a lot of frustration among teams.
For a 2x2 cipher in order to be invertable ad-bc mod 26 has to be coprime to 26
Under the current rules I don't think we have to invert 3x3s?
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Re: Codebusters C

Post by Jacobi »

Name wrote:
Umaroth wrote:Since it isn't specified in the rules, does anyone know how test writers unwittingly giving us non invertible Hill cipher matrices will be prevented? This would probably cause a lot of frustration among teams.
For a 2x2 cipher in order to be invertable ad-bc mod 26 has to be coprime to 26
Under the current rules I don't think we have to invert 3x3s?

Eh... I would say yes.

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Re: Codebusters C

Post by jlordhe »

Do you have to be extremely good at math for this event?
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Re: Codebusters C

Post by Unome »

jlordhe wrote: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).
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Re: Codebusters C

Post by TheChiScientist »

Unome wrote:
jlordhe wrote: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.
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Re: Codebusters C

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Can someone do a quick walkthrough on how to solve an RSA cipher?
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Re: Codebusters C

Post by UTF-8 U+6211 U+662F »

cryptoderes wrote:Can someone do a quick walkthrough on how to solve an RSA cipher?
Does this help?
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Re: Codebusters C

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UTF-8 U+6211 U+662F wrote:
cryptoderes wrote:Can someone do a quick walkthrough on how to solve an RSA cipher?
Does this help?
Ah yes, thank you so much!
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Re: Codebusters C

Post by UTF-8 U+6211 U+662F »

cryptoderes wrote:
UTF-8 U+6211 U+662F wrote:
cryptoderes wrote: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 :)
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