ceasar cipher python

# program to implement ceasar cipher encryption
import string

# this method takes string and shiftvalue as input and returns encrypted string as output
def encrypt(original_msg, shift_value = 1):

    allchars = string.digits + string.ascii_letters + " " + string.punctuation

    encrypted_msg = ""

    for letter in original_msg:
        if letter in allchars:
            position = allchars.index(letter)
            position += shift_value
            position %= len(allchars)
            e_letter = allchars[position]
            encrypted_msg += e_letter
        else:
            encrypted_msg += letter

    return encrypted_msg

# method that uses the encrypt method and encrypts files by reading the file path and storing the encrypted file on desktop
def encrypt_file(shift_value):
    file_path = input("Enter File path : ")
    try:
        file1 = open(file_path, 'r+')
        f2 = open("C:/Users/MOHIT/Desktop/encrypted_file.txt", 'w')
        print("File opened Successfully!!")
        file_data = file1.read()
        print("File read Successfully!!")
        encrypted_data = encrypt(file_data, shift_value)
        f2.write(encrypted_data)
        print("Encrypted File stored on Desktop successfully!!")

    except Exception as e:
        print("Problems with opening the file")
        print(str(e))

## main function

# encrypt("hello my name is mohit" , 3)
print("Program to implement Ceasar Cipher")
shift_value = int(input("Enter the shift value : "))
encrypt_file(shift_value)
# encrypt(data)

'''

Program to implement Ceasar Cipher
Enter the shift value : 5
Enter File path : F:/python_3.4/sample.txt
File opened Successfully!!
File read Successfully!!
Encrypted File stored on Desktop successfully!!

'''