## Science Olympiad at MIT Invitational 2019

Name
Member
Posts: 402
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset
Has thanked: 8 times
Been thanked: 4 times

### Re: Science Olympiad at MIT Invitational 2019

Did anyone try the RSA on the code test? I'm pretty sure they encoded it wrong by grouping it together. Then they modded it (?????) which seems to be even more wrong. Finally n is suppose to be the product of 2 primes and 96 is definitely not the product of 2 primes.
Syosset HS '21
Favorite Past Events: Microbe, Invasive, Matsci, Fermi
Events!: Astro, Code, Fossils
```Cornell/LISO/Duke/MIT/Regionals/Brown/SOUP
Astro: 2/4/2/10/2/2/3
Code: 9/1/2/1/1/1/1
Fossils: 16/13/6/9/2/3/8
1 fermi cornell, 10 orni LISO, 4 green gen regionals```

Unome
Moderator
Posts: 4250
Joined: January 26th, 2014, 12:48 pm
State: GA
Location: somewhere in the sciolyverse
Has thanked: 64 times
Been thanked: 30 times

### Re: Science Olympiad at MIT Invitational 2019

A random note - I don't think I mentioned it on the answer key, but the maps used in the Geomaps test were excerpts from the Electra Lake quadrangle in Colorado (Section F), and the Jordan Narrows quadrangle in Utah (Section L). I believe both were 7.5 minute, although I don't remember for sure.
Userpage
Chattahoochee High School Class of 2018
Georgia Tech Class of 2022

Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

pepperonipi
Wiki Moderator
Posts: 153
Joined: January 21st, 2019, 11:38 am
Division: C
State: FL
Has thanked: 38 times
Been thanked: 76 times

### Re: Science Olympiad at MIT Invitational 2019

Name wrote:Did anyone try the RSA on the code test? I'm pretty sure they encoded it wrong by grouping it together. Then they modded it (?????) which seems to be even more wrong. Finally n is suppose to be the product of 2 primes and 96 is definitely not the product of 2 primes.
How did you go about solving this? It seems like the test maker was somewhat on track (the equation is $M^e (\mod n) = C$, where $M$ is the message and $C$ is the cipher text). However, I think they did $[M (\mod n) ]^e = C$, which I don't believe is valid.

Modding it is okay for the RSA Cipher, and you are definitely supposed to do it. If you didn't you would have insanely large numbers with longer messages (like "trees").

Boca Raton Community High School
My Wiki Page | School Wiki Page | WikiProject Tournaments of States | Pi-Bot

2019: Code, Fermi, Thermo
2019 Trials: WTF (MIT), Detector (Nationals)
2020: Detector, Orni, Code (Substitution: Penn)
2020 Trials: Data Sci (Princeton)

Name
Member
Posts: 402
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset
Has thanked: 8 times
Been thanked: 4 times

### Re: Science Olympiad at MIT Invitational 2019

pepperonipi wrote:
Name wrote:Did anyone try the RSA on the code test? I'm pretty sure they encoded it wrong by grouping it together. Then they modded it (?????) which seems to be even more wrong. Finally n is suppose to be the product of 2 primes and 96 is definitely not the product of 2 primes.
How did you go about solving this? It seems like the test maker was somewhat on track (the equation is $M^e (\mod n) = C$, where $M$ is the message and $C$ is the cipher text). However, I think they did $[M (\mod n) ]^e = C$, which I don't believe is valid.

Modding it is okay for the RSA Cipher, and you are definitely supposed to do it. If you didn't you would have insanely large numbers with longer messages (like "trees").
So TREES is 19174418. They took the mod 96 of this which is 50, and they encoded 50 into 32. But when you decode 32 you would get 50 and you might as well encrypted the word OG (146) which mod 96 is also 50. It would make more sense instead to encode each letter seperately.
We didn't actually try solving this, it was worth only 200 pts so we focused on other questions.
Syosset HS '21
Favorite Past Events: Microbe, Invasive, Matsci, Fermi
Events!: Astro, Code, Fossils
```Cornell/LISO/Duke/MIT/Regionals/Brown/SOUP
Astro: 2/4/2/10/2/2/3
Code: 9/1/2/1/1/1/1
Fossils: 16/13/6/9/2/3/8
1 fermi cornell, 10 orni LISO, 4 green gen regionals```

pepperonipi
Wiki Moderator
Posts: 153
Joined: January 21st, 2019, 11:38 am
Division: C
State: FL
Has thanked: 38 times
Been thanked: 76 times

### Re: Science Olympiad at MIT Invitational 2019

Name wrote:
pepperonipi wrote:
Name wrote:Did anyone try the RSA on the code test? I'm pretty sure they encoded it wrong by grouping it together. Then they modded it (?????) which seems to be even more wrong. Finally n is suppose to be the product of 2 primes and 96 is definitely not the product of 2 primes.
How did you go about solving this? It seems like the test maker was somewhat on track (the equation is $M^e (\mod n) = C$, where $M$ is the message and $C$ is the cipher text). However, I think they did $[M (\mod n) ]^e = C$, which I don't believe is valid.

Modding it is okay for the RSA Cipher, and you are definitely supposed to do it. If you didn't you would have insanely large numbers with longer messages (like "trees").
So TREES is 19174418. They took the mod 96 of this which is 50, and they encoded 50 into 32. But when you decode 32 you would get 50 and you might as well encrypted the word OG (146) which mod 96 is also 50. It would make more sense instead to encode each letter seperately.
We didn't actually try solving this, it was worth only 200 pts so we focused on other questions.
Yeah, I think RSA is supposed to prevent things like this if it's done correctly. However, like you said earlier, 96 isn't the product of 2 primes, which I think is screwing the whole system up if you were to decode.

And like you said, it really wasn't worth contemplating a lot of time over since it was only 200 points. In the future I would have just attempted it using the encryption formula and not bothered wondering about decryption/encryption problems so that other problems could be focused on. If you knew the formula and used it right, it easily could've taken you 2 minutes or so. But then again, that would only be if the writer also used the equation right lol.

Also, congrats on the first.

Boca Raton Community High School
My Wiki Page | School Wiki Page | WikiProject Tournaments of States | Pi-Bot

2019: Code, Fermi, Thermo
2019 Trials: WTF (MIT), Detector (Nationals)
2020: Detector, Orni, Code (Substitution: Penn)
2020 Trials: Data Sci (Princeton)

Name
Member
Posts: 402
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset
Has thanked: 8 times
Been thanked: 4 times

### Re: Science Olympiad at MIT Invitational 2019

pepperonipi wrote:
Name wrote:
pepperonipi wrote:
How did you go about solving this? It seems like the test maker was somewhat on track (the equation is $M^e (\mod n) = C$, where $M$ is the message and $C$ is the cipher text). However, I think they did $[M (\mod n) ]^e = C$, which I don't believe is valid.

Modding it is okay for the RSA Cipher, and you are definitely supposed to do it. If you didn't you would have insanely large numbers with longer messages (like "trees").
So TREES is 19174418. They took the mod 96 of this which is 50, and they encoded 50 into 32. But when you decode 32 you would get 50 and you might as well encrypted the word OG (146) which mod 96 is also 50. It would make more sense instead to encode each letter seperately.
We didn't actually try solving this, it was worth only 200 pts so we focused on other questions.
Yeah, I think RSA is supposed to prevent things like this if it's done correctly. However, like you said earlier, 96 isn't the product of 2 primes, which I think is screwing the whole system up if you were to decode.

And like you said, it really wasn't worth contemplating a lot of time over since it was only 200 points. In the future I would have just attempted it using the encryption formula and not bothered wondering about decryption/encryption problems so that other problems could be focused on. If you knew the formula and used it right, it easily could've taken you 2 minutes or so. But then again, that would only be if the writer also used the equation right lol.

Also, congrats on the first.
Thanks!
Syosset HS '21
Favorite Past Events: Microbe, Invasive, Matsci, Fermi
Events!: Astro, Code, Fossils
```Cornell/LISO/Duke/MIT/Regionals/Brown/SOUP
Astro: 2/4/2/10/2/2/3
Code: 9/1/2/1/1/1/1
Fossils: 16/13/6/9/2/3/8
1 fermi cornell, 10 orni LISO, 4 green gen regionals```

waterqualityquestion
Member
Posts: 4
Joined: December 17th, 2018, 5:23 pm
Has thanked: 0
Been thanked: 0

### Re: Science Olympiad at MIT Invitational 2019

Does anyone know when the picture album is available (like the medal/trophy pictures) and where I would be able to access it?

mdv2o5
Member
Posts: 20
Joined: July 9th, 2018, 7:24 am
State: IN
Location: MA
Has thanked: 0
Been thanked: 0

### Re: Science Olympiad at MIT Invitational 2019

waterqualityquestion wrote:Does anyone know when the picture album is available (like the medal/trophy pictures) and where I would be able to access it?
All the post-tournament stuff is on their website: http://scioly.mit.edu/updates/index.html.

Name
Member
Posts: 402
Joined: January 21st, 2018, 4:41 pm
Division: C
State: NY
Location: Syosset
Has thanked: 8 times
Been thanked: 4 times

### Re: Science Olympiad at MIT Invitational 2019

Has anyone else never recieved tests/medals back yet? It's been almost a month, and we don't have them yet. We've also recieved no response yet when emailing them.
Syosset HS '21
Favorite Past Events: Microbe, Invasive, Matsci, Fermi
Events!: Astro, Code, Fossils
```Cornell/LISO/Duke/MIT/Regionals/Brown/SOUP
Astro: 2/4/2/10/2/2/3
Code: 9/1/2/1/1/1/1
Fossils: 16/13/6/9/2/3/8
1 fermi cornell, 10 orni LISO, 4 green gen regionals```

C8H10N4O2!
Member
Posts: 44
Joined: October 4th, 2018, 3:55 pm
Has thanked: 0
Been thanked: 0

### Re: Science Olympiad at MIT Invitational 2019

Name wrote:Has anyone else never recieved tests/medals back yet? It's been almost a month, and we don't have them yet. We've also recieved no response yet when emailing them.
I was wondering the same thing...

### Who is online

Users browsing this forum: No registered users and 1 guest