Java File Encryptor

The Objective of this project was to learn how to use the Java Cryptography Extension (JCE) to perform symmetric file encryption and decryption. Additionally password-based encryption and implementation for changes in recommended key lengths and algorithms were also added.

Folder Structure

The project contains two folders

• src: the folder has the FileEncryptor.java where majority of the project functionality resides and a Util.java file with some utility fuctions.
• resources: this folder is used to store all the input and output files i.e. the plaintext and ciphertext files.

How to run

Step 1: Compilation

Enter the comamnds below and after navigating to the src folder of the project through the terminal.

javac FileEncryptor.java Util.java

Step 2: Create Plaintext

Create or copy a pre-existing plaintext file and make sure it has some content within. Save it in your desired location.

echo "This is a plaintext file" >> plaintext.txt

Note: The program can encrypt any file type, not limited to just .txt

Step 3: Encryption

java FileEncryptor <action> [algorithm] [keyLength] <password> <plaintext> <ciphertext>

When encrypting a file the user has the option to specify the Algorithm and key length. However, these are only optional arguments. If they are not specified then the default values (AES with 128 bits) will be used to perform the encryption on the file.

Currently the program accepts the AES and Blowfish algorithms and its valid keylengths.

The encryption will also be successful if either the Algorithm or Key length is specified as the default value will be applied to the property that is not specified.

e.g.

java FileEncryptor enc p@ssw0rd plaintext.txt ciphertext.enc

java FileEncryptor enc 192 p@ssw0rd plaintext.txt ciphertext.enc

java FileEncryptor enc AES p@ssw0rd plaintext.txt ciphertext.enc

java FileEncryptor enc Blowfish 448 p@ssw0rd plaintext.txt ciphertext.enc

Step 4: Decryption

java FileEncryptor <action> <password> <ciphertext> <plaintext> 

The same password must be used when decrypting a previously encrypted file.

e.g.

java FileEncryptor dec p@ssw0rd ciphertext.enc decrypted.txt

Query Metadata

To query the metadata on an encrypted file enter the following command below

java FileEncryptor info ciphertext.enc

Output

All data used for encryption, decryption and authentication is printed out to the console for testing purposes.

Encryption output

<---------------------------------------->
Secret Key: 4v3GURNUyxpT+wQ7V+7lnA==
Init Vector: Myg7C+La5xo7A9czkMvSlA==
Salt: FbXNYM6ofed26t/GY27/tQ==
Mac Key: XgYmnjFXo0aKTxGMc00uVHoeNYvXBTwRV5teJM8TitU=
Mac salt: 3X0+fVGznlZQtXN+4QW7aA==
Computed Mac: yiB/ldtDwyKMt4vcPfja+TC9guC+xzgoexFj+ciC6k8=
<---------------------------------------->
INFO: Encryption finished, saved at ciphertext.enc

Decryption output

<---------------------------------------->
Secret Key: 4v3GURNUyxpT+wQ7V+7lnA==
Init Vector: Myg7C+La5xo7A9czkMvSlA==
Salt: FbXNYM6ofed26t/GY27/tQ==
Mac Key: XgYmnjFXo0aKTxGMc00uVHoeNYvXBTwRV5teJM8TitU=
Mac salt: 3X0+fVGznlZQtXN+4QW7aA==
Computed Mac: yiB/ldtDwyKMt4vcPfja+TC9guC+xzgoexFj+ciC6k8=
Given Mac: yiB/ldtDwyKMt4vcPfja+TC9guC+xzgoexFj+ciC6k8=
<---------------------------------------->

INFO: Authentication passed, file integrity maintained
INFO: Decryption complete, open decrypted.txt

Info Query output

Metadata for file: resources/ciphertext.enc

<---------------------------------------->
Algorithm: AES
Key length: 128
Blocksize: 128
<---------------------------------------->
Init Vector: 2VZe+7ogcuQfOia7mbd38w==
Salt: zVhJUB7OfMrw8b6si4L2AQ==
Mac salt: i9iRZ+Mzb2LxNx9rptCzQQ==
Computed Mac: fqbGjJGIeFaqA2TMmBTFrdjgPEEIk57lIV0dUhevxSM=
<---------------------------------------->