an implementation of DES algorithm in python3
-k [KEY] -> the key must be of length 8 bytes, so 8 chars or 16 hex digits (if -x is set)
-p [PLAIN] -> plaintext
-c [CIPHER] -> ciphertext
-m [MODE] -> mode of operation (ECB, CBC, OFB, CFB, CTR)
-i [IV] -> initialization vector... not required in ECB mode
-x -> if set all inputs will be read as hex values
-P -> add 8 bytes of padding to plaintext before the encryption
-I -> pad IV if it's less than 8 bytes
-r -> raw output