iEncrypter

iEncrypter is a simple AES encrypt / decrypt sample program using OpenSSL's lib.

The program contains following features:

• Encrypt a file using AES algorithm (Password or key file).
• Decrypt a file using AES algorithm (Password or key file).
• Generate a key file from password.

Well, actually, the key file is just a 32-characters-long MD5 hash value, which is perfect for OpenSSL's AES key.

User manual

To use this program, please use the following command:

File Encryption

• Using password:

ien encrypt -i [Input] -o [Output] -p [Password]

For example:

ien encrypt -i "1.txt" -o "2.txt" -p "123456"

• Using key file:

ien encrypt -i [Input] -o [Output] -k [Key Path]

For example:

ien encrypt -i "1.txt" -o "2.txt" -k "key.txt"

File Decryption

• Using password:

ien decrypt -i [Input] -o [Output] -p [Password]

For example:

ien decrypt -i "2.txt" -o "3.txt" -p "123456"

• Using key file:

ien decrypt -i [Input] -o [Output] -k [Key Path]

For example:

ien decrypt -i "2.txt" -o "3.txt" -k "key.txt"

Key file generation

ien genkey -o [Output] -p [Password]

For example:

ien genkey -o "key.txt" -p "123456"

Build from source

• On Windows: You need nmake.
• On Unix based systems (Including OSX): You need command make to work.
  • On mac, you can use Homebrew to install make.
  • On Linux, you can use your favorite package manager to install make or GNU make.

Inside the system

The encryption and decryption uses AES_Encrypt and AES_Decrypt. Key gen uses MD5.

Take AES_Encrypt for example:

The OpenSSL's aes.h defines blocks with length of 16. Which means that all the plaintext and ciphertext must have length no more than 16. Any string longer than 16 will be ignored.

And even though you may get ciphertexts longer or shorter than 16, they are indeed 16 characters. You can use strlen() to verify that.

Another thing to be noticed: You must memset all the input and output character arrays. Don't ask why, you can try.

Other things such as file operations, they have nothing to talk about. Anyone with some basic knowledge of programming can read them easily (probably).

Postscript

You may wonder why I wrote this. Well, as you can see, encryption programs like OpenSSL's official CMD tools, they usually contains large amount of codes. It's hard to find a simple program that encrypts and decrypts files.

That's right, this program is written for studying purpose.

License

This project has inherited the dual OpenSSL and SSLeay license from OpenSSL, I guess.

Or what else, I don't know.