encrypt.py

result = ''
message = ''
choice = ''

while choice != 0:
	choice = input("\nWould you like to encrypt or decrypt the message?\nEnter 1 to encrypt, or 2 to decrypt. Enter 0 to exit program.")

	if choice == '1':
		message = input("\nEnter message for encryption: ")
		for i in range(0, len(message)):
			result = result + chr(ord(message[i]) - 3)

		print(result + '\n\n')
		result = ''

	elif choice == '2':
		message = input("\nEnter a message for decryption: ")
		for i in range(0, len(message)):
			result = result + chr(ord(message[i]) + 3)

		print(result + '\n\n')
		result = ''

	elif choice != '0':
		print("Invalid input. Please try again. \n\n")	

# Tutorial provided by David Kaplan