Skip to content

Instantly share code, notes, and snippets.

@sathwikv143

sathwikv143/pyAes.py

Last active Apr 5, 2019
Embed
What would you like to do?
File Encryption and Decryption with python
#!/usr/bin/python3
# pyAesCrypt script
import argparse
import getpass
from sys import exit
from os.path import isfile
import pyAesCrypt
maxPassLen = 1024 # maximum password length (number of chars)
# encryption/decryption buffer size - 64K
bufferSize = 64 * 1024
# parse command line arguments
parser = argparse.ArgumentParser(description=("Encrypt/decrypt a file "
"using AES256-CBC."))
parser.add_argument("filename", type=str,
help="file to encrypt/decrypt")
parser.add_argument("-o", "--out", type=str,
default=None, help="specify output file")
parser.add_argument("-p", "--password", type=str,
default=None, help="specify the password")
# encrypt OR decrypt....
groupED = parser.add_mutually_exclusive_group(required=True)
groupED.add_argument("-e", "--encrypt",
help="encrypt file", action="store_true")
groupED.add_argument("-d", "--decrypt",
help="decrypt file", action="store_true")
args = parser.parse_args()
# check for input file existence
if not isfile(args.filename):
exit("Error: file \"" + args.filename + "\" was not found.")
# check if the user has not supplied a password
if not args.password:
# prompt the user for password
passw = str(getpass.getpass("Password:"))
else:
# warn the user
print("Warning: passing passwords as plaintext "
"command-line arguments may be unsafe.")
# get the password from the argument
passw = args.password
if args.encrypt:
# check against max password length
if len(passw) > maxPassLen:
exit("Error: password is too long")
# Check password complexity
# here assume that a good password is at least 8 chars long
# and includes at least:
# 1 lowercase char
# 1 uppercase char
# 1 digit
# 1 symbol
if not((len(passw) > 7) and any(c.islower() for c in passw)
and any(c.isupper() for c in passw)
and any(c.isdigit() for c in passw)
and any(not(c.isalnum()) for c in passw)):
print("Warning: your password seems weak.")
print("A password should be at least 8 chars long and should "
"contain at least one lowercase char, one uppercase char, "
"one digit and one symbol.")
# re-prompt the user for password
# if it was not supplied from the command line
if not args.password:
passwConf = str(getpass.getpass("Confirm password:"))
# check the second pass against the first
if passw != passwConf:
exit("Error: passwords you provided do not match")
# open output file
if args.out is not None:
ofname = args.out
else:
ofname = args.filename+".aes"
# call encryption function
try:
pyAesCrypt.encryptFile(args.filename, ofname, passw, bufferSize)
# handle IO errors
except IOError as ex:
exit(ex)
# handle value errors
except ValueError as ex:
exit(ex)
elif args.decrypt:
# open output file
if args.out is not None:
ofname = args.out
elif args.filename.endswith(".aes"):
ofname = args.filename[:-4]
else:
exit("Error: if input file extension is not \".aes\", you should "
"provide the output file name through \"-o\" option.")
# call decryption function
try:
pyAesCrypt.decryptFile(args.filename, ofname, passw, bufferSize)
# handle IO errors
except IOError as ex:
exit(ex)
# handle value errors
except ValueError as ex:
exit(ex)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment