This is a stand-alone cipher-utility that uses openssl crypto-library AES_256 and SHA1 to encrypt/decrypt any file.

Prerequisites

Software	Version
openssl	1.0.2o

Check to see if you already have openssl on your machine.

$ openssl version

If you already have openssl installed on your system. Please check the version by typing openssl version. This program will work with any version of openssl.

If not, install using the direction from openssl's site or follow the direction below:

For Ubuntu:

$ sudo apt-get update && apt-get install -y vim openssl libssl-dev

For Mac using Homebrew:

$ brew update
$ brew install openssl

If you get error: 'openssl/evp.h' file not found then you might need to do the following:

$ cd /usr/local/include 
$ ln -s ../opt/openssl/include/openssl .

Note: If you have a version above 1.0.2o. And you want to encrypt/decrypt with cipher-utility program and then encrypt/decrypt using built-in openssl command, you will need to pass the -md md5 flag. Because the latest version uses sha1 as a message digest by default.

How to run the program

First, clone this repo:

    $ git clone https://github.com/Joy57/Cipher-Utility.git

1. Run the make command.
2. Run executable file ./cipher.

Note: If you modify or make changes to the code please make sure to run make clean and then follow the above step to run the program again.

When you run the executable cipher, it will provide the following direction for usage.

Usage: ./cipher -[e|d] [-nosalt] -in infile -out outfile -p password

By defualt the progam is set to salt for security purpose. It is recommended to use salt for any type of encryption/decryption especially with a stream cipher.

Example usage:

Encryption using salt

Decryption using salt

if you would like to make sure your file wasn't corrupted or changed due to encryption/decryption. Type the following command

sample.jpg is your original file and dec.jpg is your decrypted file.

$ diff sample.jpg dec.jpg

Output should be nothing in the case of successful encryption/decryption.

If you want to encrypt/decrypt using -nosalt. Then type the following:

Encrypt

$ ./cipher -e -in sample.jpg -out enc.jpg -p iLoveMagic

Decrypt

$ ./cipher -d -in enc.jpg -out dec.jpg -p iLoveMagic

Incase you forget to pass the -p flag for password. You will be prompted to enter password.

License