def shift_cipher(shift, message):
if shift < 0 or shift > 26 or type(message) is not str:
return message
cipher = ""
offset = ord('a')
message = message.lower()
for char in message:
cipher += chr(offset + (ord(char) + shift - offset) % 26)
return cipher
from sys import argv
if __name__ == "__main__":
if len(argv) < 3:
exit()
try:
shift = int(argv[1])
f = open(argv[2])
except (IOError, ValueError), e:
print e
else:
message = ""
for line in f.readlines():
message += line.rstrip() # remove \n
print shift_cipher(shift, message)
f.close()