Using 7-Zip to Encrypt and Decrypt files

Encryption is a way of encoding information so that it cannot be read without the appropriate key to decode it. You can use 7-Zip, software available on LSE campus machines and also downloadable on the internet, to encrypt and decrypt files and make them more secure.

The guidance below is for PC users. To download an install 7-Zip, see the 7-Zip website|. Mac users can install and use Ez7Z, which should be able to read and process 7-Zip encrypted files. Find out more here|.

On an LSE campus machine, you will find 7-Zip in the Start Menu | All Programs | Utilities. If 7-Zip isn't on your campus machine, please contact the IT Service Desk (it.servicedesk@lse.ac.uk|) to get it installed.

Creating an encrypted file

  1. In 7-Zip, navigate to the file you want to encrypt. Just like in Windows Explorer, click on folders to open them.
  2. When you've reached the right folder that contains the file you want to encrypt, right-click on the file. Select 7-Zip and click on Add to Archive...

    The Add to Archive screen will appear.


  3. The only details you need to enter are the Encryption Password. Enter a password of your choice, then re-enter to confirm.

    Remember that any encryption is only as good as the password used to encrypt it. Stick by the LSE password rules when using encryption:
    • The password must be at least 8 characters long
    • The password must contain at least one capital letter
    • The password must contain at least one lowercase letter
    • The password must contain at least one numeral
  4. Make sure AES-256 is selected under Encryption Method.


  5. Click OK and an encrypted version of the file will b created inside a zip file. By default, you will find this next to the original file.

Decrypting 7-Zip files

  1. If you receive an email with a 7-Zip encrypted attchment, or are otherwise given a file encrypted by 7-Zip, first save the attachment where you can easily find it e.g. your H: Space.
  2. Open 7-Zip and navigate to where you saved your file. Double-click to open the zip file and display the contents.


  3. Double-click the document and you will be asked for a password. Enter the agreed password and the document will open.

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