Tuesday, August 25, 2009

Creating a self extracting encrypted archive with 7zip

This is a walk-through on how to create a self extracting archive that is encrypted. This is a good way to add security to a file you need to email. What does that mean?

self extracting – a file that will uncompress and unencrypt itself when you double click it

archive – a compressed file containing all the files you need to protect. Compression helps you get by the pesky limits set by gmail etc where you can only send a 20MB attachment. If you have some excel data or word docs you can usually decrease the size by 5-10X.

encrypted – this will encrypt with the AES256 algorithm. The longer the password you use, the more secure it is.

This assumes you have 7zip installed. To check, right click on any file. If 7zip is in your menu like in the screenshot below, it is installed. If you do not, click this link which will pop up a new window with a walk through video on installing 7zip.

To get started -

Put the files in a folder that you want to encrypt.
Open the folder containing the files, drag your mouse across all the files, and right click. Look at this picture:

7zip-add-to-archive

So Right click

7zip

click Add to archive

The 7zip window should come up. You need to check the following settings:

7zip-options1Add a name.exe

Check Create SFX archive – the self extracting part

Enter a password, the longer the better, numbers and special characters add a lot to the security of the file. I can break into a file with 5 characters in a few minutes. 8+ characters with a letters, numbers and a special character are ideal. A sentence is even better.

Check show password if you want.

Leave encryption at AES-256 and Check encrypt file names.

Hit Ok

This will create your encrypted .exe file in the folder with your files.

Now you need to rename the file.

7zip-rename

Now select the file. You should be able to see the extensions like .txt .docx .xlsx .exe. If you can’t click here for instructions on how to have those show up.

Right click on your .exe file and click rename. (or click the file and hit F2 for the fast nerd way to rename)

Erase the .exe part and hit enter. Te 7z icon should disappear and a blank page of paper icon should be there.

Now just open your email, attach the file and send it to the person who needs it. Don’t ever put the password in the email or you defeat the purpose of doing this. The best way is to call the person and tell them what the password is.

When the recipient of the email saves the file, they need to add .exe back to the name using this same rename process. We can’t send .exe files in email because viruses would be everywhere if you could do that.


From: http://windowsnerd.com/how-to-for-normal-people/creating-a-self-extracting-encrypted-archive-with-7zip/


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