A Simple (70 Lines of Code) File Encryption Tool using 128-bit AES

Propose

We developed an AES based file encryption tool. By encrypting a file with a strong password, nobody can access the original file without knowing the password.

Features:

File encryption with user supplied password
Encryption algorithm is 128-bit AES in OFB mode
Command line user interface
Encrypt single file or all files in a directory
Implemented with 70 lines of C# source code

Source Code and Compilation

In Windows operating system, download aes_ofb.zip and double click build.bat to build executable aes_ofb.exe.

How to Use

To encrypt a file with a password:

aes_ofb.exe file password

The newly created file with .aes extension is the encrypted file. Original file is not modified.

To encrypt all files in a directory with a password:

aes_ofb.exe path password

To decrypt an encrypted file, process it with aes_ofb.exe and same password.

Security Considerations

Use a Strong Password

Though 128-bit AES is considered unbreakable, a weak password is still vulnerable.

Encrypt Each File with Different Password

Please encrypt each file with different password before you understand stream cipher attacks.