Encrypt Text or File Using OpenKeychain/PGP (Android)

Install

• https://www.openkeychain.org/
• https://play.google.com/store/apps/details?id=org.sufficientlysecure.keychain
• https://f-droid.org/app/org.sufficientlysecure.keychain

Setup

I am using PGP for personal text or file encryption, not for communication with another party via email or messaging app.

Why use PGP? Why not AES? I like that PGP have existing apps on various platform (Android, Windows, Linux, etc.) with standardize implementation (I can be sure encryption using App A on Platform B can be decrypted using App C on Platform D).

Create Key

Click CREATE MY KEY. (access via Manage my keys from tripple-horizontal-dot)

• name: since I am not using for communication with another party, specify a purpose or function as the name (e.g. test). I would recommend lowercase and no case if you plan to use the same key on PC as well.
• email: email if required, though you can specify invalid email like test. To avoid warning and inconvinience, I would use email like [email protected].
• Publish on keyservers: not necessary as I am not using it for communication with another party

Click CREATE KEY

For added security, you can assign password to your key.

• Select test key.
• Click Change Password (access from tripple-horizontal-dot)

Encrypt

Select test key.

The first icon is encrypt files.

The second icon is encrypt text.

In the encrypt screen

• Lock icon: which is the encryption key to be used.
• Sign icon: identify of the sender (the party who encrypt this). Since we are not using this for communication with another party, sign is optional.

Use the share icons to share the encrypted files to another apps (maybe DropBox or WhatsApp). You can also save to local device (fro files) or copy to clipboard (for text).

You can also

• Select files from another App and click Share, then select Encrypt with OpenKeychain.
• You can select/highlight text from any App, then click share and select Encrypt or Encrypt with OpenKeychain.

Decrypt

There is a few ways to decrypt.

• Click on triple-horizontal-lines and select Encrypt/Decrypt. You can import files and copy from clipboard.
• Select files from another App and click Share: If the filename ends with .asc or .pgp, there should be a Descrypt with OpenKeychain.
• You can select/highlight text from any App, then click share and select Descrypt with OpenKeychain.

References:

• Export Android Openkeychain Private Key to PC (Linux)