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May 3, 2021, 4:10:58 AMMay 3

to sage-support

''' I have the RSA code, code works when we give input to encryption and take decryption output (plaintext and output are same), but when we encrypt plaintext separately and take its output and give it to decryption code as input separately, the output, is not the same as encryption input (plaintext and output are not same). Can someone please explain why is this happening? '''

# code begins

import sympy

from datetime import datetime

from sage.all import ZZ, GF

start_time = datetime.now()

print("RSA Encryption and Decryption")

print("Values of 'p' AND 'q' are as follows:")

p = sympy.randprime(2, 100) #Input Prime Number

print ("p = ", p)

q = sympy.randprime(2, 100) #Input Prime Number

print ("q = ", q)

s = sympy.randprime(2, 100) #Input Prime Number

print ("s = ", s)

n = p * q * s

print("")

print ("RSA Modulus,n = ",n) #RSA Modulus

r = (p-1)*(q-1)*(s-1) #Eulers Toitent

e = ZZ.random_element(r)

while gcd(e, r) != 1: #GCD

e = ZZ.random_element(r) #e Value Calculation

print("")

print ("Public Key = ", e)

bezout = xgcd(e, r);

d = Integer(mod(bezout[1], r)); #d, Private Key

print("")

print ("d =", d)

print("")

text = 'samu'

print("")

print ("Message, m = ", text)

m = [ord(c) for c in text]

c = [power_mod(i, e, n) for i in m] #Encryption

print(c)

cipher = [chr(a) for a in c]

print ("Ciphertext, cipher =", cipher)

print('')

'''

cipher = input("Enter Cipher text to be decrypted") #cipher input

print('Cipher text to be decrypted :', cipher) '''

c = [ord(a) for a in cipher] #conversion of cipher text to the list of ascii values c

print('c =',c)

d = [power_mod(j, d, n) for j in c] #Decryption

print('d =',d)

characters = [chr(ascii) for ascii in d]

print("")

print ("Decrypted text, d = ", ''.join(characters))

print("")

print ("Plaintext/ Message, m = ", text)

print ("Decrypted Message, d = ", ''.join(characters))

if(text == ''.join(characters)):

print ("Thus we encrypted and decrypted text using RSA algorithm")

else:

print("Not sucessfull")

end_time = datetime.now()

print('Time taken for execution of the program: {} '.format(end_time - start_time))

# code ends

May 3, 2021, 3:29:25 PMMay 3

to sage-support

How are you manually entering the `Ciphertext` for decryption?

Ciphertext, cipher = ['㓔', '\U000107ee', '퇫', '뺸']

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