bash script hook lda_mailbox_autocreate for generate mail-crypt user encrypted private key with user password

What it is way most best for causing bash script run (as root) of time mailbox created (lda_mailbox_autocreate)?

I use dovecot 2.3.4.1 in Debian 10.

And I use of mail-crypt-plugin https://doc.dovecot.org/configuration_manual/mail_crypt_plugin/

I setup mail-crypt for requiring user encrypted EC key (mail_crypt_require_encrypted_user_key = yes). I want for passphrase encrypt EC key using client plaintext password. There is credential no stored on server. But for user with use password too bad, I concatenate user plaintext password with random salt. And then string to SHA512() hash and use as decryption key (mail_crypt_private_password) for EC private key.

For above I have plugin config

mail_plugins = $mail_plugins mail_crypt plugin { mail_crypt_curve = secp256k1 mail_crypt_require_encrypted_user_key = yes mail_crypt_save_version = 2 }

And for returning userdb_mail_crypt_private_password, I have sql query

password_query = SELECT username, password,
SHA2( CONCAT('%w',salt), 512 ) AS userdb_mail_crypt_private_password
FROM virtual_users WHERE username='%u';

But how I generate key of user automatically? Note for generating key of user, I need user password plaintext. I never save plaintext password of user of the server.

Also user of note creates in PHP of web of the server. And for security I do not allow PHP exec shell (php.ini disabled_functions). Definitely not leaving PHP doveadm access!

For solving subject to generate user key encrypted, I do imap of call of the service 'imap-postlogin' the service likes document "Post-login scripting' write https://doc.dovecot.org/admin_manual/post_login_scripting/

And 'imap-postlogin' execute my custom script with 'script-login' binary https://github.com/dovecot/core/blob/8606e1abb90a1c91357b84bf547a89564d05353...

Here it is config for above

service imap { executable = imap imap-postlogin } service imap-postlogin { executable = script-login /usr/local/bin/generateKeys.sh unix_listener imap-postlogin { } }

And generateKeys.sh it is script simple for generating keys with sha256() hash product mysql. Variable of note ${MAIL_CRYPT_PRIVATE_PASSWORD} automatically put of 'userdb_mail_crypt_private_password' return of mysql field of query when documented https://doc.dovecot.org/admin_manual/post_login_scripting/running-surroundin...

Fields returned by userdb lookup with their keys uppercased (e.g. if userdb returned home, it's stored in HOME).

Here generatekeys.sh

#!/bin/bash if [ /usr/bin/doveadm mailbox cryptokey list -u "${USER}" -U > /dev/null | wc -l -lt 2 ]; then /usr/bin/doveadm -o "plugin/mail_crypt_private_password=${MAIL_CRYPT_PRIVATE_PASSWORD}" mailbox cryptokey generate -u "${USER}" -U > /dev/null fi exec "$@"

This work! But I want more good. By why execute each login? Possible has generateKeys.sh execute in the times only of dovecot create mailbox (lda_mailbox_autocreate) instead?