I want to encrypt a file using AES-256. How can I do that quickly and easily, and how can I - or someone else -decrypt it again?
Unfortunately, there is no easy solution to securing your stuff. Think about your use-case, maybe something other than plain AES is better suited.
If you want very simple platform independent encryption, you can use openssl.
Please note: You can use this to hide birthday-gift-ideas.txt from your roommate, but don't expect it to be secure against a determined attacker!
If you still want to use openssl:
You can get openssl to
Note that you have a choice of ciphers and modes of operation. For normal use, I recommend aes 256 in CBC mode. These are the ciphers modes you have available (only counting AES):
OpenSSL will ask you for a password. This is not an encryption key, it is not limited to 32 bytes! If you're going to transfer files with someone else, your shared secret should be very strong. You can use this site to get a sense of how good your password is:
7z (when the password option is used) uses a 256bit AES encryption (with SHA256 key stretching).
Install it (
For decryption, right click on the .7z file and choose Extract here.
I like to use the
This will ask for a passphrase.
You can also add
The linked website contains an open-source 256-bit aes encrypt/decrypt tool and is multiplatform - MacOs, Windows, Linux and others through Java.
You could backup and encrypt your home folder using the syntax:
Download the binaries or source-code from the website.