MHB Cryptography: RSA Message decryption

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The discussion revolves around solving an RSA decryption problem involving the message "BSSM." The user attempted to convert the message into a numerical format and applied the RSA decryption formula but struggled to derive the correct letters from the resulting number. A fellow participant clarified the decryption process, confirming that the final number, 1371, can be converted to the letters "CAT" through modulus and division operations. The key steps included converting the message to a number, applying the decryption key, and then translating the numerical result back into letters. The conversation highlights the importance of correctly following the RSA decryption steps to achieve accurate results.
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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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