RSA Encryption From Scratch - Math & Python Code

here is the code if you are lazy to write: import random import math # n= p.q #phi(n) = phi(p.q)=phi(p).phi(q) = (p-1). (q-1) #phi(n) = (p-1.q-1) def is_prime (number): if number < 2: return False for i in range (2, number // 2 +1): if number % i == 0: return False return True def generate_prime (min_value, max_value): prime = random.randint (min_value, max_value) while not is_prime(prime): prime = random.randint(min_value, max_value) return prime def mod_inverse(e, phi): for d in range (3, phi): if (d * e) % phi == 1: return d raise ValueError ("Mod_inverse does not exist!") p, q = generate_prime(1000, 50000), generate_prime ( 1000, 50000) while p==q: q= generate_prime(1000, 50000) n = p * q phi_n = (p-1) * (q-1) e = random.randint (3, phi_n-1) while math.gcd(e, phi_n) != 1: #gcd=greater common denometer != not equal e = random.randint (3, phi_n - 1) d = mod_inverse(e, phi_n) message = input("Enter your message to Encrypt ") print ("Prime number P: ", p) print ("Prime number q: ", q) print ("Public Key: ", e) print ("Private Key: ", d) print ("n: ", n) print ("Phi of n: ", phi_n, " Secret") message_encoded = [ord(ch) for ch in message] print ("Message in ASCII code: ", message_encoded) # (m ^ e) mod n = c ciphertext = [pow(ch, e, n) for ch in message_encoded] print (message," Ciphered in: ", ciphertext) Decodemsg= [pow(ch, d, n) for ch in ciphertext] print ("back to ASCII: ", Decodemsg) msg = "".join (chr(ch) for ch in Decodemsg) print("from ASCII to TEXT: ", msg)

Please keep this type of in-depth video coming! I learned a tremendous amount from your clear explanations, and am able to implement my own programs based on your clear, and logical, step-by-step walk through. Please, more like this!!! 😃

Not gonna lie, this was the best explanation I've ever seen so far. I've gone through textbooks, random forums, etc. but this one explained the math very very well and got rid of the knowlege gaps I had

Good one. Yes, thorough explanation covering Maths and all is much beneficial than just demonstration of using some libraries. There are tons of people out there who would follow the second approach. And that makes you standout.

This "from the scratch" is sooo well done , Bravo

lerady knew the RSA process, but having it done in code makes it very clear and easy to follow.

A year late to the party, but thanks for the great explanation and the fantastic demo in Python. I'm familiar with the concepts of RSA already, but it's always good to have it explained clearly for folk who haven't looked at the concepts and logic behind it and your explanation was great.

This is the best explanation of RSA I've ever seen

I really like these more theory based videos explained from scratch. In this way, I really learned something deep.

Thank you, thank you, thank you. Crazy how a YouTuber can explain better than professors