问我正在写一个代码在python的RSA加密和解密字符串使用ascii代码，但解密算法的计算很慢。

EN

import math

def gcd(m,n): 
    if n==0: 
        return m 
    else: 
        return gcd(n,m%n) 

def encrypt(ascii_initial, e, n):
    ascii_final = []
    for i in ascii_initial:
        C1= pow(i,e)
        C=C1%n
        print("value of C is:",C)  
        ascii_final.append(C)
    return ascii_final
def decrypt(ascii_initial, d, n):
    ascii_final = []
    for j in ascii_initial:
    #decryption
        P1=pow(j,d)
        P=P1%n
        ascii_final.append(P)
        print("value of P is:",P)  
    #returning final list
    return ascii_final   
def rsa_algorithm (direction, ascii_initial):
    p,q,r,s = 13, 17, 61, 37
    

n= p*q*r*s
print("RSA Modulus(n) is:",n)

# pub_key = int(input("Enter a starting value for public key generation "))
f_of_n = (p - 1) * (q - 1) * (r-1) * (s-1)
# print("Eulers Toitent(r) is:",f_of_n)
#gcd
for e in range(2,f_of_n): 
    if gcd(e,f_of_n)== 1: 
        break

for i in range (1,f_of_n):
    d= 1+f_of_n *i/e
    if d % e==0:
        d = int(d/e) 
        break
    
print("value of d is:",d)  

#public key generation

# decalaring empty list
# ascii_final = []
#Cypher text=Encryption
#checking whether to encode or decode

if direction =="encode":
    ascii_final =  encrypt(ascii_initial,e,n)

elif direction == "decode":
    ascii_final = decrypt(ascii_initial, d, n)

return ascii_final
cont = 'yes'
while cont.lower() == 'yes':
#checking whether user wants encoding or decoding
    u_direction=input("Type 'encode' for encrypting and 'decode' for decrypting: ")
    if u_direction == 'encode':
               
    user_entered_string = input(f"Enter the String to be {u_direction}d: ")
    user_entered_string = user_entered_string
    #converting into the ascii code dec
    ascii = []
    for letter in user_entered_string:
        ascii.append(ord(letter))
    print(ascii)
    #calling our rsa_algorithm function
    resultant_ascii = rsa_algorithm(u_direction,ascii)

    print(f"your encode ascii list is {resultant_ascii}")





if u_direction == 'decode':
    input_string = input('Enter elements of a list separated by and , space')
    print("\n")
    ascii = input_string.split(', ')
    # print list
    print('list: ', ascii)

    # convert each item to int type
    for i in range(len(ascii)):
        # convert each item to int type
        ascii[i] = int(ascii[i])

    resultant_ascii = []
    resultant_ascii = (rsa_algorithm(u_direction,ascii))
    print(resultant_ascii)
    final = resultant_ascii[0]
    s = ''.join(chr(i) for i in resultant_ascii)
    print(s)
cont = input("Do you want to continue type 'yes' to continue or 'no' to stop: ")