- 19th Oct 2021
- 03:18 am

import random import time import psutil def gcd(a, b): while b != 0: a, b = b, a % b return a def multiplicative_inverse(e, phi): d = 0 x1 = 0 x2 = 1 y1 = 1 temp_phi = phi while e > 0: temp1 = temp_phi//e temp2 = temp_phi - temp1 * e temp_phi = e e = temp2 x = x2 - temp1 * x1 y = d - temp1 * y1 x2 = x1 x1 = x d = y1 y1 = y if temp_phi == 1: return d + phi def is_prime(num): if num == 2: return True if num < 2 or num % 2 == 0: return False for n in range(3, int(num**0.5)+2, 2): if num % n == 0: return False return True def generate_key_pair(p, q): if not (is_prime(p) and is_prime(q)): raise ValueError('Both numbers must be prime.') elif p == q: raise ValueError('p and q cannot be equal') # n = pq n = p * q # Phi is the totient of n phi = (p-1) * (q-1) # Choose an integer e such that e and phi(n) are coprime e = random.randrange(1, phi) # Use Euclid's Algorithm to verify that e and phi(n) are coprime g = gcd(e, phi) while g != 1: e = random.randrange(1, phi) g = gcd(e, phi) # Use Extended Euclid's Algorithm to generate the private key d = multiplicative_inverse(e, phi) # Return public and private key_pair # Public key is (e, n) and private key is (d, n) return ((e, n), (d, n)) def encrypt(pk, plaintext): # Unpack the key into it's components key, n = pk # Convert each letter in the plaintext to numbers based on the character using a^b mod m cipher = [pow(ord(char), key, n) for char in plaintext] # Return the array of bytes return cipher def decrypt(pk, ciphertext): # Unpack the key into its components key, n = pk # Generate the plaintext based on the ciphertext and key using a^b mod m aux = [str(pow(char, key, n)) for char in ciphertext] # Return the array of bytes as a string plain = [chr(int(char2)) for char2 in aux] return ''.join(plain) if __name__ == '__main__': print("===========================================================================================================") print("================================== RSA Encryptor / Decrypter ==============================================") print(" ") p = int(input(" - Enter a prime number (17, 19, 23, etc): ")) q = int(input(" - Enter another prime number (Not one you entered above): ")) print(" - Generating your public / private key-pairs now . . .") public, private = generate_key_pair(p, q) print(" - Your public key is ", public, " and your private key is ", private) message = input(" - Enter a message to encrypt with your public key: ") encrypted_msg = encrypt(public, message) print(" - Your encrypted message is: ", ''.join(map(lambda x: str(x), encrypted_msg))) print(" - Encryption Time is: ",time.time(),"ms") print(" - Decrypting message with private key ", private, " . . .") print(" - Decryption Time is: ",time.time(),"ms") print(" - Your message is: ", decrypt(private, encrypted_msg)) print (" - CPU usage: ", psutil.cpu_percent(),"%") print (" - Memory Storage: ",psutil.virtual_memory()) print(" - Key Generation Time: ",time.time()) print(" ") print("============================================ END ==========================================================") print("===========================================================================================================")

**About The Author - Janhavi Gupta**

Seasoned programmer with 6 years of experience in designing, developing, and deploying software solutions. Strong problem-solving skills coupled with the ability to collaborate effectively in multidisciplinary teams. Continuously learning and adapting to new technologies and methodologies to drive innovation and deliver high-quality, user-centric solutions.