## Codebusters C

TheWood
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Posts: 11
Joined: February 20th, 2019, 2:30 pm
Division: C
State: GA

### Re: Codebusters C

Sorry mb for not posting earlier.

Find the inverse of the following hill encryption key:
BRA
CEL
ETS

KITN1931
Member
Posts: 1
Joined: February 27th, 2019, 10:19 pm

### Re: Codebusters C

Can someone give me tips on solving patristocrats????

CongminhTran
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Posts: 2
Joined: October 12th, 2017, 4:17 pm
State: -

### Re: Codebusters C

Hey guys,

I was just wondering if any of you guys could help me with the Hill Cipher, both decryption and encryption?

For encryption, how do you make an encryption matrix given plaintext- ciphertext letter pairs?

For decryption, how do you make a decryption matrix given plaintext-ciphertext letter pairs? Also, how do you decrypt when given a key and some ciphertext? Lastly, what if they ask you to produce a decryption matrix given only some plaintext (with number values all arranged in a matrix)? I was asking because at the Regionals test for my school, a couple of Hill Cipher questions where you had to produce A (the other one was THE) decryption matrix showed up, and we had no idea on how to do them.

If you guys could try to help, I would very much appreciate that!

jimmy-bond
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Posts: 311
Joined: January 8th, 2018, 11:25 pm
Division: C
State: HI
Location: On Earth, I think

### Re: Codebusters C

CongminhTran wrote:Hey guys,

I was just wondering if any of you guys could help me with the Hill Cipher, both decryption and encryption?

For encryption, how do you make an encryption matrix given plaintext- ciphertext letter pairs?

For decryption, how do you make a decryption matrix given plaintext-ciphertext letter pairs? Also, how do you decrypt when given a key and some ciphertext? Lastly, what if they ask you to produce a decryption matrix given only some plaintext (with number values all arranged in a matrix)? I was asking because at the Regionals test for my school, a couple of Hill Cipher questions where you had to produce A (the other one was THE) decryption matrix showed up, and we had no idea on how to do them.

If you guys could try to help, I would very much appreciate that!
KITN1931 wrote:Can someone give me tips on solving patristocrats????

These should go under the Code Busters thread under "Lab Events".
If life gives you melons, you're dyslexic.

Why can't dinosaurs ski? Because they're dead.

Season's over, I can sleep now.

2019 States

2018 Nats

2017 Nats

Name
Member
Posts: 274
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset

### Re: Codebusters C

TheWood wrote:Sorry mb for not posting earlier.

Find the inverse of the following hill encryption key:
BRA
CEL
ETS

This year's rules doesn't cover inverting 3x3 hill keys.
However it should be

(I kinda stole this question, but I really liked the way they presented the Bacon cipher)
ADELE DEALT DEREK LAMPS DATED AS THE BLUNT CELLO DEALT FREED ACTORS GETS A DEATH FLYER EAGLE A YEAR YELLS OFTEN A ROAD
The first 4 letters in the ciphertext is "real"
SW 16-17 Syosset 18-21. Previous main events: Microbe, Invasive, Herp, Matsci, Fermi
Hoping to do Astro, Code, Ornith, and maybe Compound next year
2018-19 highlights

dragonfruit35
Exalted Member
Posts: 277
Joined: February 28th, 2015, 7:49 am
Division: C
State: VA
Location: TJHSST

### Re: Codebusters C

Name wrote:(I kinda stole this question, but I really liked the way they presented the Bacon cipher)
ADELE DEALT DEREK LAMPS DATED AS THE BLUNT CELLO DEALT FREED ACTORS GETS A DEATH FLYER EAGLE A YEAR YELLS OFTEN A ROAD
The first 4 letters in the ciphertext is "real"

Hmmm... KINDA...

PS: I think you added an extra "S" at the end of ACTORS, because that makes six letters in the group.

2018

2019

Goooooooo Colonials!!!

Name
Member
Posts: 274
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset

### Re: Codebusters C

dragonfruit35 wrote:
Name wrote:(I kinda stole this question, but I really liked the way they presented the Bacon cipher)
ADELE DEALT DEREK LAMPS DATED AS THE BLUNT CELLO DEALT FREED ACTORS GETS A DEATH FLYER EAGLE A YEAR YELLS OFTEN A ROAD
The first 4 letters in the ciphertext is "real"

Hmmm... KINDA...

PS: I think you added an extra "S" at the end of ACTORS, because that makes six letters in the group.

Yup and oops yeah I did.
SW 16-17 Syosset 18-21. Previous main events: Microbe, Invasive, Herp, Matsci, Fermi
Hoping to do Astro, Code, Ornith, and maybe Compound next year
2018-19 highlights

dragonfruit35
Exalted Member
Posts: 277
Joined: February 28th, 2015, 7:49 am
Division: C
State: VA
Location: TJHSST

### Re: Codebusters C

Decode this Vigenere-encrypted text where the five-letter key saved physicists from using Coulomb’s law infinitely for the rest of their lives.

zhy w-xoefv wwuudk felg atscvw g cifvacngj zhul ay ih klgtcu wwucdahrcme

hint:

big hint:

2018

2019

Goooooooo Colonials!!!

starfruit
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Posts: 29
Joined: February 24th, 2018, 3:51 am
Division: B
State: VA

### Re: Codebusters C

the e-field equals zero inside a conductor that is in static equilibrium
2019 events-
potions&poisons/heredity/crimebusters/codebusters

dragonfruit35
Exalted Member
Posts: 277
Joined: February 28th, 2015, 7:49 am
Division: C
State: VA
Location: TJHSST

### Re: Codebusters C

starfruit wrote:the e-field equals zero inside a conductor that is in static equilibrium

2018

2019

Goooooooo Colonials!!!

starfruit
Member
Posts: 29
Joined: February 24th, 2018, 3:51 am
Division: B
State: VA

### Re: Codebusters C

Translate the following message into Affine when x=12 and y=3

skittles-taste the rainbow
2019 events-
potions&poisons/heredity/crimebusters/codebusters

UTF-8 U+6211 U+662F
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Posts: 1464
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Division: C
State: PA

### Re: Codebusters C

starfruit wrote:Translate the following message into Affine when x=12 and y=3

skittles-taste the rainbow

Anomaly
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### Re: Codebusters C

UTF-8 U+6211 U+662F wrote:
starfruit wrote:Translate the following message into Affine when x=12 and y=3

skittles-taste the rainbow

wait, is it me or is that not a valid key? i thought that x can't be coprime with 26 or else it leads to letters being repeated...
Orefield MS SO 2015-2018, Parkland HS SO 2019
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Riptide
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### Re: Codebusters C

Anomaly wrote:
UTF-8 U+6211 U+662F wrote:
starfruit wrote:Translate the following message into Affine when x=12 and y=3

skittles-taste the rainbow

wait, is it me or is that not a valid key? i thought that x can't be coprime with 26 or else it leads to letters being repeated...

yeah I believe the letters would start repeating after half of the alphabet?
University of California at Berkeley '23
Seven Lakes High School '19
Seven Lakes Junior High '15

hippo9
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Posts: 242
Joined: March 12th, 2018, 9:35 am
Division: C
State: IN

### Re: Codebusters C

Riptide wrote:
Anomaly wrote:
UTF-8 U+6211 U+662F wrote:

wait, is it me or is that not a valid key? i thought that x can't be coprime with 26 or else it leads to letters being repeated...

yeah I believe the letters would start repeating after half of the alphabet?

As evidenced by e and r both encoding to Z. (There's probably more, I just saw these)
"If we knew what we were doing, it wouldn’t be called research." - Albert Einstein

2018: Battery Buggy, Road Scholar, Roller Coaster
2019: Chemistry Lab, Codebusters, Disease Detectives, Fossils, Geologic Mapping, Sounds of Music