sf2 1.4.0

Encrypt and decrypt your file with Fernet algorithm

SF2

This piece of software is used to encrypt, decrypt and edit text file.

Disclaimer : You use SF2 as is, with no guarantee of results. I cannot be responsible for any loss, alteration or disclosure of data.

Why use SF2 ?

• Encrypt or decrypt text file like your personal diary
• Transfert over wire one small file
• Edit a note text file you want to keep private

Why not use SF2 ?

• Encrypt large file like video
• Protect yourself against NSA, DGSI, CIA, etc
• Protect financial/military/compromat
• In no case where a guarantee would be necessary

Understand the behavious

The encryption use the Fernet algorithm (specification), which use following strong algorithm :

• AES 128 with CBC mode (encryption)
• HMAC-SHA256 (authentication/integrity)
• IV is created with robust random function (os.getrandom)

It uses a password (symetric algorithm with preshared key). The key derivation function - the way the password is processed to get a key - is the PBKDF2HMAC algorithm with 16 bytes random salt and 480000 iterations.

Currently (19/08/2022), these algorithms are considered safe.

Any security problem ? gignops+security->gmail.com

How to use it

Now that the boring stuff is said, let's move on to the interesting part.

Install

At first you need to install SF2. You have two options :

• From the repo :
  • git clone https://github.com/laulin/sf2.git
  • python3 -m build
  • pip3 install build/sf2-*-py3-none-any.whl
• [Recommanded] pip3 install sf2
• From the github releases, download the binary file, copy it to /usr/local/bin and make it executable of all. Currently only for X86/debian based.

Encrypt

To encrypt a file, run this command :

sf2 -e -i your_plaintext_file.txt -o your_encrypted_file.x

Enter the password twice and it will create the encrypted version (your_encrypted_file.x) or your source file (your_plaintext_file.txt).

Decrypt

To decrypt a file, run this command :

sf2 -f -i your_encrypted_file.x -o your_decrypted_file.txt

Verify

To check a password on a file, run this command :

sf2 --verify -i your_encrypted_file.x

After entering the password, it will display "OK" or "FAILED !". I think it's pretty clear

Edit with external GUI

You can edit your file, but with external editor (nano, vim, mousepad, etc). Default is mousepad :

sf2 --edit -i your_encrypted_file.x

To select another editor (let's say nano) :

sf2 --edit -i your_encrypted_file.x --editor nano

Create a new encrypted file

To create a new empty and encrypt file, run this command :

sf2 --n -i your_empty_encrypted_file.x

Practical considerations

If you expect to protect a file from a data disclosure in case of hardware theft, never store you sensitive file on the hardware. If you need to use another editor than the one included in SF2, you must extract your file to a RAM partition (TMPFS, RAMFS). Prefered using --external option in this case, more easy.

Supported system

I currently only work on linux (Debian based distributions). I don't known how it works on other OS.

Acknowledgement

Thanks to Spartan Conseil for the sponsoring !