Codebusters B/C

[awesomeaidan123]

I didn't take this test, but simply from the score distribution, there must have been about 2 very tough high-scoring problems (So that the 3 highest placements could be so far from the rest of the pack). Looking at the test, it must have been Questions 7 and 8, but it's more probable that the timed question made the difference. This is a great test nonetheless, a good mix of tough and easy!

- Aidan

[xxmanacledxx]

After my team had taken the test at our last invitational, we saw that we were deducted points—in other words, we weren’t given points for a code we hadn’t fully completed before the timer rang. My question is do we not get partial points for a code that we half way completed? It was the Hill cipher by the way.

Also, any advice in solving patristocrat/aristocrat ciphers much faster?

[awesomeaidan123]

I think that the grading of all questions follows this format:
After 2 mistakes, you will deduct 100 points for each following error.
For example, let's say the word happy is worth 300 points,
If you write "jazzy" that will be 3 mistakes therefore you subtract 100 points (3-2=1) and you will receive 200 points
In general, to receive credit for a question you must either fully solve it or, have a maximum of about 5 mistakes (depending on the worth of the problem)

And for your second question, it's just practice, there isn't much else you can do.

[polkadoka]

Is there any way to quickly do caesar ciphers? I'm trying to improve my " quick maths" skills but it's not very prominent now. Is there a trick that can help? Or is it just practice practice practice?

[awesomeaidan123]

Are we allowed to rip up our tests?
It's a lot easier to split up the test if just rip pages out. We place them back in order at the end, but will we get points off for doing it?

[Umaroth]

Are we allowed to rip up our tests?
It's a lot easier to split up the test if just rip pages out. We place them back in order at the end, but will we get points off for doing it?

Iirc they're required to let you

[adatta0517]

Hello, I was working on RSA encryption/decryption, and in the practice tests, I found a problem but don't understand how the problem was set up and how they got the solution.

Here is the problem:
Megan, has faithfully followed the steps of the RSA key-generation algorithm. Here are the results:
p = 341
q = 623
n = 232481
Φ = 341271
e = 235663
Unfortunately, Megan doesn't know how to compute the value of d and needs you to do that final step for them.
Enter the computed value of d, NOT the formula.

The answer was 263119, but I don't understand how they did it. Also, Φ= (p-1)(q-1), but 340*622 is not 341271... so I'm just confused with this.
Can someone help? Thank you!

[Umaroth]

Hello, I was working on RSA encryption/decryption, and in the practice tests, I found a problem but don't understand how the problem was set up and how they got the solution.

Here is the problem:
Megan, has faithfully followed the steps of the RSA key-generation algorithm. Here are the results:
p = 341
q = 623
n = 232481
Φ = 341271
e = 235663
Unfortunately, Megan doesn't know how to compute the value of d and needs you to do that final step for them.
Enter the computed value of d, NOT the formula.

The answer was 263119, but I don't understand how they did it. Also, Φ= (p-1)(q-1), but 340*622 is not 341271... so I'm just confused with this.
Can someone help? Thank you!

RSA is not a part of Codebusters this year btw

[redscience]

Hello ! can we create codebusters test on scilympiad for practice ? The format for Sclympiad and Toebes is different hence I was wondering if there is a solution for it ?

Thank you

[Longivitis]

Hello ! can we create codebusters test on scilympiad for practice ? The format for Sclympiad and Toebes is different hence I was wondering if there is a solution for it ?

Thank you

Not that I believe so unless you're hosting that specific Scilympiad site, but I think practicing on Toebes is good enough. Toebes is still trying to implement it within Scilympiad but I'm not sure about the progress of it (was a bit of a tragedy both times it was attempted).