gnupg_encrypt

// to generate a key type in gpg --gen-key in the command line// to export public key gpg --export -a "User Name" > public.key<?phpputenv("GNUPGHOME=/tmp");// it assumes public key exists in the /tmp/keys folder$publicKey = file_get_contents(getenv('GNUPGHOME') . '/keys/public.key');    $gpg = new gnupg();    $gpg->seterrormode(gnupg::ERROR_EXCEPTION);    $info = $gpg->import($publicKey);    $gpg->addencryptkey($info['fingerprint']);    $uploadFileContent = file_get_contents('/tmp/file-to-encrypt');    $enc = $gpg->encrypt($uploadFileContent);    echo $encHope this helps

After spending some time trying to get this extension to work, I've found that you have to have the GNUPGHOME environment variable set so that the keychain can be found, and have it set equal to the .gnupg directory itself, not the apache/httpd user's home directory (which is what is shown in dan's example code).  below is an example of this and a simple function I was working on at the time to encrypt a piece of data for storage in a database.<?php    // set the environment so gnupg can find the keyring    putenv("GNUPGHOME=/home/apache/.gnupg");    function encrypt_string($str,$fingerprint) {        $res = gnupg_init();        gnupg_addencryptkey($res,$fingerprint);        $enc = gnupg_encrypt($res, $str);        return $enc;    }?>

If you're using CentOS 8 and you're having folder permissions problems, remember to disable SELinux during development. (/etc/selinux/config), just change to disabled or permissive. Then when your project is going live switch it back to enforcing and add the proper se context.

ExamplesGetting Key Information<?phpputenv('GNUPGHOME=/home/sender/.gnupg');// create new GnuPG object$gpg = new gnupg();// throw exception if error occurs$gpg->seterrormode(gnupg::ERROR_EXCEPTION); // get list of keys containing string 'example'try {  $keys = $gpg->keyinfo('example');  print_r($info);} catch (Exception $e) {  echo 'ERROR: ' . $e->getMessage();}?>Encrypt a Simple Mail<?php// set path to keyring directory// set path to keyring directoryputenv('GNUPGHOME=/home/sender/.gnupg');// create new GnuPG object$gpg = new gnupg();// throw exception if error occurs$gpg->seterrormode(gnupg::ERROR_EXCEPTION); // recipient's email address$recipient = 'dgar@example.org';// plaintext message$plaintext = "Dear Dave,\n  The answer is 42.\nJohn";// find key matching email address// encrypt plaintext message// display and also write to filetry {  $gpg->addencryptkey($recipient);  $ciphertext = $gpg->encrypt($plaintext);  echo '<pre>' . $ciphertext . '</pre>';  file_put_contents('/tmp/ciphertext.gpg', $ciphertext);} catch (Exception $e) {  die('ERROR: ' . $e->getMessage());}?>Decryption The Mail<?php// set path to keyring directoryputenv('GNUPGHOME=/home/recipient/.gnupg');// create new GnuPG object$gpg = new gnupg();// throw exception if error occurs$gpg->seterrormode(gnupg::ERROR_EXCEPTION); // recipient's email address$recipient = 'dgar@example.org';// ciphertext message$ciphertext = file_get_contents('/tmp/ciphertext.gpg');// register secret key by providing passphrase// decrypt ciphertext with secret key// display plaintext messagetry {  $gpg->adddecryptkey($recipient, 'guessme');  $plaintext = $gpg->decrypt($ciphertext);  echo '<pre>' . $plaintext . '</pre>';} catch (Exception $e) {  die('ERROR: ' . $e->getMessage());}?>

HiI found that the apache or httpd user (or whichever user the webserver is using to run) needed to have write access to the .gnupg directory for the gnupg_php functions to work. This could be your problem.  It seems a rather unsatisfactory feature of this module - gnupg keeps giving warnings that it is unsafe.

This is a simple example of a Procedural use of import addencryptkey and encrypt. Obviously in a real world use you would only be importing the key once.<?phpputenv("GNUPGHOME=/tmp");$pubkey = "-----BEGIN PGP PUBLIC KEY BLOCK-----Version: GnuPG v1.2.6 (GNU/Linux)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jHPH-----END PGP PUBLIC KEY BLOCK-----";$enc = (null);$res = gnupg_init();echo "gnupg_init RTV = <br/><pre>\n";var_dump($res);echo "</pre>\n";$rtv = gnupg_import($res, $pubkey);echo "gnupg_import RTV = <br/><pre>\n";var_dump($rtv);echo "</pre>\n";$rtv = gnupg_addencryptkey($res, "C25F29936D9046D73A77DCF8244F423AED8F1481");echo "gnupg_addencryptkey RTV = <br /><pre>\n";var_dump($rtv);echo "</pre>\n";$enc = gnupg_encrypt($res, "just a test to see if anything works");echo "Encrypted Data: " . $enc . "<br/>";?>