Enable Encrypted email via Roundcube Enigma plugin

#Install gpg package first

apt install  gnupg  gnupg gpgv2-agent

vi plugins/enigma/config.inc.php

<?php

// Enigma Plugin options
// --------------------

// A driver to use for PGP. Default: "gnupg".
$config['enigma_pgp_driver'] = 'gnupg';

// A driver to use for S/MIME. Default: "phpssl".
$config['enigma_smime_driver'] = 'phpssl';

// Enables logging of enigma operations (including Crypt_GPG debug info)
$config['enigma_debug'] = false;

// REQUIRED! Keys directory for all users.
// Must be writeable by PHP process, and not in the web server document root
$config['enigma_pgp_homedir'] = '/home/.../x/x/x/enigma_home/';

// Location of gpg binary. By default it will be auto-detected.
// This is also a way to force gpg2 use if there are both 1.x and 2.x on the system.
$config['enigma_pgp_binary'] = '/usr/bin/gpg';

// Location of gpg-agent binary. By default it will be auto-detected.
// It's used with GnuPG 2.x.
$config['enigma_pgp_agent'] = '/usr/bin/gpg-agent';

// Location of gpgconf binary. By default it will be auto-detected.
// It's used with GnuPG >= 2.1.
$config['enigma_pgp_gpgconf'] = '';
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