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Making a program that encrypts a txt file of the users choice and then saving the encrypted version as a separate file. It should also be able to decrypt the a file if the correct 8 character key is entered. The problem I'm having is that when decrypting the file characters from the end of the file seem to be cut out or left off and I can't see why. When decrypting the outcome anything after the "an" of "lance" is left out.

Text File (Pastebin)
Python Code (Pastebin)

from random import randint



def menu(): #Main menu

    choice = int(input("Encrypt [1] Decrypt [2] Exit [3]: ")) #Allows choice

    print("")



    if choice == 1: #Goes to the function for each option

        encrypt()

   elif choice == 2:

        decrypt()

    elif choice == 3:

        print("Good bye")



def encrypt(): #Encrypt

    print("Enter the name of the file you wish to encrypt(with the file 

    ending)") # Need the file ending to work

    targetFile = input("-> ")

    print('')

    f = open(targetFile, "r+") #Opens the file as 'f'

    print(f.read()) #Prints the text in the file



    key = 

    for i in range(0,8):

        chrKey = randint(33,126)

        newKey = str(chr(chrKey))  #converts ascii number to text

        key.append(newKey)

    print('')

    print("Remember the eight character key or you can't decrypt your file")

    print('Your eight character key is:')

    print(''.join(key))

    print('')



    keyTotal = 0

    for j in range(0,8):

        newValue = ord(key[j])

        keyTotal += newValue

    offset = keyTotal/8-32

    offset = int(offset)



    with open(targetFile) as f:

        characters = 0

        for line in f:

            wordslist=line.split()

            characters += sum(len(word) for word in wordslist)

    characters = int(characters)



    cypherText = 

    with open(targetFile, 'r+') as f:

        data = f.read().replace('n','')

        for k in range(0,characters):

            if data[k] != ' ':

                asciiValue = ord(data[k])

                asciiValue += offset

                if asciiValue > 126:

                    asciiValue -= 94

                cypherText.append(str(chr(asciiValue)))

            else:

                cypherText.append(' ')

        cypherText = ''.join(cypherText)



    encryptedFilename = input("Enter the filename for the encrypted file 

    (with file ending): ")

    with open(encryptedFilename, 'w+') as cf:

        cf.write(cypherText)

        print("Encryption Complete")

        print("")

    menu()



def decrypt():

    print("Enter the name of the file you wish to decrypt(with the file 

    ending)")

    targetFile = input("-> ")

    f = open(targetFile, "r+")

    print(f.read())



    print("Please enter the eight character code for decryption")

    key = input("-> ")

    keyLength = len(key)

    keyTotal = 0

    if keyLength != 8:

        print("Please enter the eight character code for decryption")

        key = input("-> ")

    for k in range(0,8):

        newValue = ord(key[k])

        keyTotal += newValue

    offset = keyTotal/8-32

    offset = int(offset)



    with open(targetFile) as f:

        characters = 0

        for line in f:

            wordslist=line.split()

            characters += sum(len(word) for word in wordslist)

    characters = int(characters)



    realText = 

    with open(targetFile, 'r+') as f:

        data = f.read().replace('n','')

        for k in range(0,characters):

            if data[k] != ' ':

                asciiValue = ord(data[k])

                asciiValue -= offset

                if asciiValue < 33:

                    asciiValue += 94

                realText.append(str(chr(asciiValue)))

            else:

                realText.append(' ')

        realText = ''.join(realText)

        print(realText)



menu()