Technically creating and encrypting folder key does not require decrypting user's private key. All folder keys are encrypted with user's public key.
Problem is for that this is a new user. The new user has no private key. I need for generating that private key. It do not the sense encrypts something using a key public if there is no private key. Both key public and private is mathematically related and have to be created together. I am using the wrong command for creating the main user encrypted EC private key?
Directing my question primary: it is any way to have the dovecot executes a bash script in the time of the mailbox created (lda_mailbox_autocreate)?
Also, I notice extra behavior when I do:
- I creates user in mysql database
- I confirms it not exists mailbox for user
- I confirms it not exists cryptokeys for user
root@localhost:/var/vmail# doveadm mailbox cryptokey list -u newuser -U Folder Active Public ID root@localhost:/var/vmail#
- Before create mailbox or cryptokeys for user, I send mail from exist user to new user
- Postfix Delivers mail to dovecot
- The dovecot accepts mail for new user and create mailbox automatically (lda_mailbox_autocreate)
- I check and see that dovecot creates key of user
root@localhost:/var/vmail# doveadm mailbox cryptokey list -u newuser -U Folder Active Public ID yes XYZ root@localhost:/var/vmail#
How the possible??? I have put in settings of mail-crypt that keys of user have to be encrypted (mail_crypt_require_encrypted_user_key = yes), but I supply no key! How the dovecot creates main user encrypted public/private EC keypair without key of encryption given?
I confirm that element of post for 'newuser' is encrypted, but of course I can no decrypt the mail. I achieve error:
dovecot: imap(newuser...Error: Mailbox INBOX: UID=1: read() failed...Private key not available: Cannot decrypt key XYZ
No well for executing generateKeys.sh on user first login. What if the user receives email before first login? How I execute generateKeys.sh on create of mailbox and how I do emails incoming without any keypair created? For to reject or queue or save unencrypted until I generate keypair? It possible?
On Sun, December 8, 2019 08:04, Aki Tuomi via dovecot wrote:
Technically creating and encrypting folder key does not require decrypting user's private key. All folder keys are encrypted with user's public key.
Aki
On 08/12/2019 09:42 uxqex4efpu--- via dovecot < dovecot@dovecot.org> wrote:
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/8606e1abb90a1c91357b84bf547a89564d05 3533/src/util/script-login.c
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 ${MAIL_CRYPT_PRIVATE_PASSWORD}
automatically put of 'userdb_mail_crypt_private_password' return of mysql
field of query when documented
https://doc.dovecot.org/admin_manual/post_login_scripting/running-surroun dings
Fields returned by userdb lookup with their keys uppercased
(e.g. if userdb returned home, it's stored in HOME).
Here generatekeys.sh
#!/bin/bash
if [ `/usr/bin/doveadm mailbox cryptokey list -u "${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?
Aki Tuomi