Encrypting a file into ascii key

Question

I am trying to encrypt a file input by user into a randomized key of ascii. I got the random key and can translate the string in the file into ascii but cannot figure out how to translate it into the key

I tried many things but am not good enough in python to understand what else to try/ what I could be doing wrong

import random

lst = list(range(1,128)) #for key
numbersran = list()

while len(numbersran) < 128:
    candidate = random.randint(1,128)
if candidate not in numbersran:
    numbersran.append(candidate)

listsdict = dict(zip(lst,numbersran)) #makes the key
print("Encytption key=", listsdict)
print()

filename=input("Enter File: ")
file=open(filename, "r")
filetxt=file.readlines()
file.close()        #for user input file

with open('file name here','r') as f:   #also cant figure out how to make this work with user inputted file
    for x in f:
        arr=list(x)

ctd=list(map(str,map(ord,arr))) 

filename=filename.replace('.txt','')
encrypt=open(filename,"w") 
#below is for the encryption process

Answer 1

import random

lst = list(range(1,128)) #for key
# numbersran = list()

# while len(numbersran) < 128:
#     candidate = random.randint(1,128)
# if candidate not in numbersran:
#     numbersran.append(candidate)
random.shuffle(lst)

listsdict = dict(zip(lst, range(1,128))) #makes the key
print("Encytption key=", listsdict)
print()

filename=input("Enter File: ")
# file=open(filename, "r")
# filetxt=file.readlines()
# file.close()        

with open(filename, "r") as file:
    filetxt = file.read()
    ascii_codes = [ord(c) for c in filetxt]


# with open('file name here','r') as f:   #also cant figure out how to make this work with user inputted file
#     for x in f:
#         arr=list(x)

# ctd=list(map(str,map(ord,arr))) 

# listdict is the key!
encrypted_codes = [listsdict[code] for code in ascii_codes]

print(encrypted_codes)


cypher = "".join([chr(c) for c in encrypted_codes])

print(cypher)
# filename=filename.replace('.txt','')
# encrypt=open(filename,"w") 
#below is for the encryption process