In this chapter, let us discuss decryption of files in cryptography using Python. Note that for decryption process, we will follow the same procedure, but instead of specifying the output path, we will focus on input path or the necessary file which is encrypted.

Code

The following is a sample code for decrypting files in cryptography using Python −

#!/usr/bin/python
# ---------------- READ ME ---------------------------------------------
# This Script is Created Only For Practise And Educational Purpose Only
# This Script Is Created For http://bitforestinfo.blogspot.in
# This Script is Written By
#
#
##################################################
######## Please Don''t Remove Author Name #########
############### Thanks ###########################
##################################################
#
#
# =================Other Configuration================
# Usages :
usage = "usage: %prog [options] "
# Version
Version="%prog 0.0.1"
# ====================================================
# Import Modules
import optparse, sys,os
from toolkit import processor as ps
def main():
   parser = optparse.OptionParser(usage = usage,version = Version)
   parser.add_option(
      ''-i'',''--input'',type = ''string'',dest = ''inputfile'',
      help = "File Input Path For Encryption", default = None)
   
   parser.add_option(
      ''-o'',''--output'',type = "string",dest = ''outputfile'',
      help = "File Output Path For Saving Encrypter Cipher",default = ".")
   
   parser.add_option(
      ''-p'',''--password'',type = "string",dest = ''password'',
      help = "Provide Password For Encrypting File",default = None)
      (options, args) =  parser.parse_args()
      # Input Conditions Checkings
      if not options.inputfile or not os.path.isfile(options.inputfile):
         print " [Error] Please Specify Input File Path"
         exit(0)
      if not options.outputfile or not os.path.isdir(options.outputfile):
         print " [Error] Please Specify Output Path"
         exit(0)
      if not options.password:
         print " [Error] No
         exit(0)
      inputfile = options.inputfile
      outputfile = options.outputfile
      password = options.password
      work = "D"
      ps.FileCipher(inputfile,outputfile,password,work)
      return
if __name__ == ''__main__'':
   main()

You can use the following command for executing the above code −

python pyfilecipher-decrypt.py -i encrypted_file_path -p password

Output

You can observe the following code when you execute the command shown above −

Note − The output specifies the hash values before encryption and after decryption, which keeps a note that the same file is encrypted and the process was successful.