Cryptography: RSA Message decryption

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Discussion Overview

The discussion revolves around the decryption process of an RSA message, specifically focusing on converting a string into a numerical format, applying the RSA decryption formula, and interpreting the resulting number back into a string. The scope includes mathematical reasoning and technical explanation related to cryptography.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant expresses difficulty in solving an RSA decryption problem and requests hints or methods from others.
  • Another participant suggests converting the string "BSSM" into a number using a specific scheme and then applying the RSA decryption formula.
  • A participant calculates the numerical representation of "BSSM" as 30224 and applies the decryption formula, resulting in the number 1371.
  • There is a claim that the answer to the decryption is "CAT," with a breakdown of how the number 1371 corresponds to the letters.

Areas of Agreement / Disagreement

There is no clear consensus on the correctness of the decryption process, as one participant claims the answer is "CAT," while another expresses uncertainty about converting the resulting number back into letters.

Contextual Notes

The discussion does not clarify the assumptions behind the conversion methods or the specific encryption scheme used, leaving some steps and definitions unresolved.

ertagon2
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I've been trying to solve this question for quite a while now. I watched a ton of videos on RSA. But whenever I try to solve it I get weird answers. Can some pls give me a hint or their method of solving it. An answer to the question also would be fine.
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ertagon2 said:
I've been trying to solve this question for quite a while now. I watched a ton of videos on RSA. But whenever I try to solve it I get weird answers. Can some pls give me a hint or their method of solving it. An answer to the question also would be fine.

Hi ertagon2! Welcome to MHB!

What did you try?

Logically we would need to convert BSSM to a number using the same scheme as is used for encryption.
Then decode it with the given deciphering key.
And then convert the resulting number to a string again by taking the number modulus 26, dividing it by 26, and repeating.
 
I like Serena said:
Hi ertagon2! Welcome to MHB!

What did you try?

Logically we would need to convert BSSM to a number using the same scheme as is used for encryption.
Then decode it with the given deciphering key.
And then convert the resulting number to a string again by taking the number modulus 26, dividing it by 26, and repeating.

So i did convert BSSM to a number.
B= 1 S= 18 S= 18 M= 12, temp= 1*26^3 + 18*26^2 + 18*26^1 + 12*26^0 = 30224

According to the internet the deciphering process goes like this:
temp^d mod n = message

So
30224^26767 mod 46927 = 1371

And I can't convert 1371 to letters.I tried but I didn't get a good answer.
 
The answer is CAT
 
ertagon2 said:
So i did convert BSSM to a number.
B= 1 S= 18 S= 18 M= 12, temp= 1*26^3 + 18*26^2 + 18*26^1 + 12*26^0 = 30224

According to the internet the deciphering process goes like this:
temp^d mod n = message

So
30224^26767 mod 46927 = 1371

And I can't convert 1371 to letters.I tried but I didn't get a good answer.

ertagon2 said:
The answer is CAT

Let's see...

1371 mod 26 = 19, which corresponds to T.
1371 div 26 = 52, 52 mod 26 = 0, which corresponds to A.
52 div 26 = 2, which corresponds to C.

Yep. CAT.
 

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