question about Mailcrypt plugin

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question about Mailcrypt plugin

Dovecot mailing list
Hi everybody,

I have a question about the Dovecot Mailcrypt Plugin.
I'm trying to understand what the security of this plugin is based on.

The encryption with private and public key and elliptic curves is basically a good thing. But the keys are in the file system together with the encrypted mails. The passwords for the private keys are in the user database.
I guess the passwords have to be in plaintext for it to work.

Is that true, or did I misunderstand something?
Then the encryption would make no sense at all, right?
For what purpose was the plugin developed?

Can anyone explain this to me?

Best regards

Daniel

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Re: question about Mailcrypt plugin

Dovecot mailing list

On 14/09/2019 16:08 Daniel Niewerth via dovecot < [hidden email]> wrote:


Hi everybody,

I have a question about the Dovecot Mailcrypt Plugin.
I'm trying to understand what the security of this plugin is based on.

The encryption with private and public key and elliptic curves is basically a good thing. But the keys are in the file system together with the encrypted mails. The passwords for the private keys are in the user database.
I guess the passwords have to be in plaintext for it to work.

Is that true, or did I misunderstand something?
Then the encryption would make no sense at all, right?
For what purpose was the plugin developed?

Can anyone explain this to me?

Best regards

Daniel

It's best suited for securing external storage such as NFS or object storage. There are possibilities to encrypt the key using user's password, but this takes careful planning. The keys can also come from userdb , e.g. LDAP.
---
Aki Tuomi
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Re: question about Mailcrypt plugin

Dovecot mailing list
Hi Aki,

Thank you so much for your answer.

Does "encryption with user password" mean that the key is encrypted with the password that the imap client sends to the server?

That would be exactly the solution I am looking for. 
The user password is nowhere in plain text, but only as a hash in the SQL database. 
This would make the setup safe. 

How do I tell Dovecot that this password should be used?

I think I have to create a keypair for the user with doveadm-mailbox-cryptokey and encrypt it with the password that is hashed in the SQL database. Right?
I am aware that I always have to change the Keypair password together with the mailbox password. 
Do I have to pay attention to anything else?

Best regards

Daniel

Am 14.09.2019 um 15:52 schrieb Aki Tuomi via dovecot <[hidden email]>:


On 14/09/2019 16:08 Daniel Niewerth via dovecot < [hidden email]> wrote:


Hi everybody,

I have a question about the Dovecot Mailcrypt Plugin.
I'm trying to understand what the security of this plugin is based on.

The encryption with private and public key and elliptic curves is basically a good thing. But the keys are in the file system together with the encrypted mails. The passwords for the private keys are in the user database.
I guess the passwords have to be in plaintext for it to work.

Is that true, or did I misunderstand something?
Then the encryption would make no sense at all, right?
For what purpose was the plugin developed?

Can anyone explain this to me?

Best regards

Daniel

It's best suited for securing external storage such as NFS or object storage. There are possibilities to encrypt the key using user's password, but this takes careful planning. The keys can also come from userdb , e.g. LDAP.
---
Aki Tuomi


smime.p7s (3K) Download Attachment