https://cebulka.in/en/tags/android/ Recent content in Android on Cebulka Blog Hugo en-US Sat, 17 Aug 2024 12:05:00 +0000 https://cebulka.in/en/posts/pgp-openkeychain/ Sat, 17 Aug 2024 12:05:00 +0000 https://cebulka.in/en/posts/pgp-openkeychain/ <p>OpenKeyChain is a free Android app for managing PGP keys and encrypting messages. This guide describes how to install and how to use OpenKeyChain on Android.</p> <h2 class="heading" id="setup"> Installing OpenKeyChain on Android<span class="heading__anchor"> <a href="#setup">#</a></span> </h2><ol> <li>Download OpenKeyChain from Google Play or install it using F-Droid.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-049.jpg" alt="Google Play 1" width="50%"> </figure> <ol start="2"> <li>If you choose to install via F-Droid, it&rsquo;s recommended to download and install F-Droid via your computer to ensure you&rsquo;re downloading from a trusted source. You can find instructions and verify the checksum here: <a href="https://f-droid.org">How to install F-Droid</a>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-040.png" alt="F-Droid 1" width="50%"> </figure> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-041.png" alt="F-Droid 2" width="50%"> </figure> <ol start="3"> <li>Once F-Droid is installed, search for OpenKeyChain and install the app.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-003.jpg" alt="F-Droid 4" width="50%"> </figure> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-002.jpg" alt="F-Droid 4" width="50%"> </figure> <blockquote> <p>In OpenKeyChain, privacy-threatening functionalities <em>Key Search</em> and <em>Synchronization</em> are enabled by default. Before further use of the app, make sure that the mentioned features were disabled in the app settings.</p> </blockquote> <h2 class="heading" id="keygen"> Generating keys in OpenKeyChain<span class="heading__anchor"> <a href="#keygen">#</a></span> </h2><ol> <li>Open the OpenKeyChain app and press <em>+</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-061.jpg" alt="OpenKeyChain main screen with Generate a New Key option" width="50%"> </figure> <ol start="2"> <li>Select the <em>Create My Key</em> option.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-062.jpg" alt="Form for entering name, surname, and email address" width="50%"> </figure> <ol start="3"> <li>Enter your nickname and press <em>NEXT</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-063.jpg" alt="Nickname entry screen" width="50%"> </figure> <ol start="4"> <li>Enter your non-existent email address and press <em>NEXT</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-064.jpg" alt="Email entry screen" width="50%"> </figure> <ol start="5"> <li>Click on the three dots and then select <em>Change key configuration</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-065.jpg" alt="Change key settings screen" width="50%"> </figure> <ol start="6"> <li>Change the key&rsquo;s password, which will be used to protect it, then change the subkeys to RSA 4096bit and press <em>Save</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-066.jpg" alt="Key password setup screen" width="50%"> </figure> <ol start="7"> <li>Set the master key accordingly and press <em>OK</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-067.jpg" alt="Master key setup screen" width="50%"> </figure> <ol start="8"> <li>Set the subkey accordingly and press <em>OK</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-068.jpg" alt="Subkey setup screen" width="50%"> </figure> <ol start="9"> <li>Press <em>Save</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-069.jpg" alt="Save changes screen" width="50%"> </figure> <ol start="10"> <li>Press <em>CREATE KEY</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-071.jpg" alt="Create key screen" width="50%"> </figure> <ol start="11"> <li>Wait for the key to be created.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-072.jpg" alt="Key creation waiting screen" width="50%"> </figure> <h2 class="heading" id="backup"> Backing up the private key in OpenKeyChain<span class="heading__anchor"> <a href="#backup">#</a></span> </h2><ol> <li>Go to the key management screen, select your private key, and click <em>Backup Key</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-075.jpg" alt="Backup 1" width="50%"> </figure> <ol start="2"> <li>Save the backup code, select the location where you want to save the key, and click <em>Save Backup</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-077.jpg" alt="Backup 2" width="50%"> </figure> <ol start="3"> <li>Ensure the key is saved in a secure location.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-079.jpg" alt="Backup 3" width="50%"> </figure> <blockquote> <p>A backup copy of the private key should be encrypted with <a href="https://www.veracrypt.fr/en/Home.html">VeraCrypt</a> or <a href="https://www.truecrypt71a.com/">TrueCrypt</a> and placed on external media for protection against data loss.</p> </blockquote> <h2 class="heading" id="import"> Importing public keys in OpenKeyChain<span class="heading__anchor"> <a href="#import">#</a></span> </h2><ol> <li>Open the email or other communication containing the public key.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-081.jpg" alt="Import keys 1" width="50%"> </figure> <ol start="2"> <li>Save the public key to a file with a .asc extension; importing a public key from the clipboard is currently not working.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-083.jpg" alt="Import keys 2" width="50%"> </figure> <ol start="3"> <li>Open the OpenKeyChain app, select the <em>Import from File</em> option. Select the saved file and click <em>Import</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-084.jpg" alt="Import keys 3" width="50%"> </figure> <ol start="4"> <li>The app will import the key and display its details.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-085.jpg" alt="Import keys 4" width="50%"> </figure> <h2 class="heading" id="encryption"> Encrypting messages in OpenKeyChain<span class="heading__anchor"> <a href="#encryption">#</a></span> </h2><ol> <li>Open the OpenKeyChain app and select <em>Encrypt/Decrypt</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-086.jpg" alt="Encryption 1" width="50%"> </figure> <ol start="2"> <li>Select the <em>Encrypt Text</em> option.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-087.jpg" alt="Encryption 2" width="50%"> </figure> <ol start="3"> <li>Paste or type the text you want to encrypt.</li> <li>Select the recipient&rsquo;s public key from the list of available keys. Then choose one of the options from the top bar: <em>Copy to Clipboard</em> or <em>Share</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-088.jpg" alt="Encryption 3" width="50%"> </figure> <ol start="5"> <li>After encrypting the message, copy the resulting text to the clipboard.</li> <li>You can now share the encrypted text in another app, such as via an instant messenger or save it to a file.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-090.jpg" alt="Encryption 4" width="50%"> </figure> <blockquote> <p>We do not need to import the public key again when encrypting the next messages. The key will be saved in the application files.</p> </blockquote> <h2 class="heading" id="decryption"> Decrypting messages in OpenKeyChain<span class="heading__anchor"> <a href="#decryption">#</a></span> </h2><ol> <li>Open the encrypted message in any text editor.</li> <li>Copy the encrypted text to the clipboard.</li> <li>Open the OpenKeyChain app and select <em>Encrypt/Decrypt</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-092.jpg" alt="Decryption 1" width="50%"> </figure> <ol start="4"> <li>Select the <em>Read from Clipboard</em> option. If prompted for a password, enter the password for your private key.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-093.jpg" alt="Decryption 2" width="50%"> </figure> <h2 class="heading" id="signing"> Signing messages in OpenKeyChain<span class="heading__anchor"> <a href="#signing">#</a></span> </h2><ol> <li>Open the OpenKeyChain app and select <em>Encrypt/Decrypt</em>, then <em>Encrypt Text</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-094.jpg" alt="Signing 1" width="50%"> </figure> <ol start="2"> <li>Select your private key.</li> <li>Paste the message content you want to sign into the text field, then click <em>Copy</em> or <em>Share</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-095.jpg" alt="Signing 2" width="50%"> </figure> <ol start="4"> <li>You can now share the signed text in another app, such as via an instant messenger.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-096.jpg" alt="Signing 3" width="50%"> </figure> <blockquote> <p>Avoid signing messages that seem universal. For example, a signed &ldquo;I agree&rdquo; or &ldquo;It&rsquo;s me&rdquo; message can be saved and used to impersonate you in another conversation. Signed messages should be complete sentences describing the purpose and circumstances of the signature.</p> </blockquote> <h2 class="heading" id="verification"> Verifying messages in OpenKeyChain<span class="heading__anchor"> <a href="#verification">#</a></span> </h2><ol> <li>Open the signed message in any text editor.</li> <li>Copy its content to the clipboard.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-105.jpg" alt="Step 1: Paste the signed text into the text field" width="50%"> </figure> <ol start="3"> <li>Open the OpenKeyChain app, go to <em>Encrypt/Decrypt</em>, then click <em>Read from Clipboard</em>.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-107.jpg" alt="Step 2: Displaying the verification result" width="50%"> </figure> <ol start="4"> <li> <p>OpenKeyChain will display the verification result, informing you whether the signature is valid.</p> </li> <li> <p>If the key is not confirmed, it may be highlighted in orange. In such a case:</p> <ul> <li>Tap on the key owner.</li> <li>Tap the three dots in the top-right corner and select <em>Confirm with Fingerprint</em>.</li> <li>Check the key&rsquo;s fingerprint to ensure it matches the expected fingerprint, then confirm the key.</li> </ul> </li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-100.jpg" alt="Step 3: Confirming the public key" width="50%"> </figure> <ol start="6"> <li>After confirming the key, the verification process should succeed.</li> </ol> <figure><img src="https://cebulka.in/en/posts/pgp-openkeychain/and-101.jpg" alt="Step 4: Key confirmation after checking the fingerprint" width="50%"> </figure> <blockquote> <p>We do not need to import the public key again when verifying subsequent signatures of the same author. The key will be saved in the app data files.</p> </blockquote> <hr>