Bezout

The Math of Cryptography: RSA

Achyut Bharadwaj
September 2021
cryptography, RSA, encryption, decryption, one-way function, factorization, prime, modular arithmetic, modular inverse, kid-RSA, Euclid's division, gcd, Bezout, Euler, totient, Fermat, primality test, Miller-Rabin

A presentation on the mathematics of cryptography, with an emphasis on RSA. A link to the slides is here.

Basic Cryptography #

Sending Messages #

Say, there are 3 people, Aditi, Bhaskar and Diti.
 
Aditi wants to send the message “HELLO” to Bhaskar, using her computer.
 
Computers, however, can only store numbers. How will she send the message “HELLO” to Bhaskar?
 
To store characters, there is a code called the ASCII code. In ASCII, each character is given a value in binary.
 
“HELLO” is coded as: 1001000 1000101 1001100 1001100 1001111
 
So, Aditi has to send the above code to Bhaskar.

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