Introduction to Encryption

What is Encryption?

Encryption is like sending secret messages between parties; if someone tries to pry without the proper keys, they won't be able to understand the message.
In other words, it is the process of locking up information using cryptography (Cryptography is both the practice and the study of hiding information.)

Definition: 

• ‘The Process of converting plain text into cipher text, something that appears to be random and meaningless’ is called as the encryption.
• Process of converting cipher text back into original text is called as decryption.

Terminology

• Original message is called as plain text/clear text. 
• Encrypted message is called as cipher text/encrypted text. 

• A Key which is a secret like a password which is used to encrypt and decrypt information. 

• Ciphers are the specific algorithms which are used to encrypt and decrypt data. A cipher is series of well-defined steps that can be followed as a procedure to encrypt and decrypt messages. 

Encryption verify and ensure;

• Data Integrity 
• Confidentiality 
• Authentication 
• Non-repudiation 

                                       of a message. 

• When key size becomes larger data is more secured. But we have to spend more time, more money, more effort and more resources to encrypt and decrypt data. 

There are two encryption methods.

1. Symmetric Encryption 
2. Asymmetric Encryption 

Symmetric Encryption 

Encryption that uses a single key/same key for both encryption and decryption. Also known as secret key encryption. Symmetric encryption is preferred when encrypting large amounts of data. The key needs to be known to the sender and the recipient. Some of the more common symmetric encryption algorithms are RC2, RC4, and Data Encryption Standard (DES). 

Asymmetric Encryption

Asymmetric encryption, or public key encryption uses what is called a key pair—a public key for encrypting a message, and a private key to decrypt it.

I have implemented a software which uses AES 128-bit algorithm to encrypt files in our computer. This software supports for text files only.

This is the Github link which contains the source code. All the instructions about locally building and setting up the app, are there in the Readme file.

https://github.com/nimeshikaranasinghe/JAVA-Encryption-Program

• IDE used- NetBeans 8.1
• Java version 8 update 60 or above is needed to run this application.

Download and run the jar file.

Here the running application

***This application can be used as a ransomware too. It looks like a simple calculator. But once you save the answer the encryption process will start.

Enter valid two number, select an operator and press calculate.

Then application then ask for a folder to save your calculated answer.

Select a folder.

By default, the current folder path is set to the place where your jar file is saved as shown in the given below picture. This is done to avoid encrypting important files of the user. If the user forgets to select a folder the README.txt file well be encrypted. So, no harm to user.

Once you select a folder the path will be shown in the text box. Then press save.

Then the answer will be saved on a Answer.txt file. And the first '.text' file on that selected folder will be encrypted.

This is the Answer.txt file

This is my sample text file before encrypt it.

This is it after encryption is done

If the destination folder doesn’t contain any text files there will be no encryption process and no files will be encrypted. And once you press the ‘Okay’ button application will terminate.

Once you click okay the decryption dialog box will appear (only if a text file was encrypted)
.

Look for passwordFile.txt to find the decryption password. It will be saved on the folder which you have selected in the previous dialog box. 
***Do not delete iv.enc file and salt.enc file. These files are used to decrypt the encrypted text file.

            (Folder content after encryption process)

As you can see in the above picture I didn’t delete the original text file (to avoid any data loss) SampeTextFile.des is the encrypted file. If you want you can modify the program to delete the original text file.

This is the passwordFile.txt file

Enter that password to the empty text box in decryption dialog box and press decrypt.

                     (Folder content after decryption process)

salt.enc and iv.enc files will be automatically deleted.
If you have any questions about my Encryption application comment here or else you can email me. :) If you want any help to do modifications to this application I'm here to help you. 
my email: nimeshika.ishani@gmail.com