QUERIES RECEIVED FROM PARENTS & STUDENTS

THE MAILBOX

Appreciate a little assistance with RSA cryptography problem

 

I'm studying computer science and engineering, but I wasn't able to follow the Math lectures,and now I’m having problems completing some Math tasks. 

I have an exam in 2 days and I badly need to pass it, please help me with the following if you can. 

The task is : 

Using Rules of RSA Cryptography by having " p = 5, q= 13, and  e=7” to DECRYPT this message 

59,57,43,00,52,00

Thanks!!!

Student X

I will get you started off then. Let's decode 59: 

p*q = 5*13 =65 

φ(n)= (p-1)*(q-1) = 4*12 =48 

The modular multiplicative inverse of e (mod φ(n)) where e=7, φ(n)=48 gives the result of 7.

 

59^7 mod(65) =2488651484819 mod (65) =19

 

For each of the remaining encrypted messages, the corresponding decrypted message is simply given by the value of M^7 mod (65), where M is the encrypted message.

 

Hope this helps. Peace.

Best Regards,

Mr Koh