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67 lines
2.5 KiB
Markdown
67 lines
2.5 KiB
Markdown
---
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title: 'Security | mail_crypt (email/storage encryption)'
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---
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!!! info
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The Mail crypt plugin is used to secure email messages stored in a Dovecot system. Messages are encrypted before written to storage and decrypted after reading. Both operations are transparent to the user.
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In case of unauthorized access to the storage backend, the messages will, without access to the decryption keys, be unreadable to the offending party.
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There can be a single encryption key for the whole system or each user can have a key of their own. The used cryptographical methods are widely used standards and keys are stored in portable formats, when possible.
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Official Dovecot documentation: https://doc.dovecot.org/configuration_manual/mail_crypt_plugin/
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---
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## Single Encryption Key / Global Method
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1. Create `10-custom.conf` and populate it with the following:
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```
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# Enables mail_crypt for all services (imap, pop3, etc)
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mail_plugins = $mail_plugins mail_crypt
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plugin {
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mail_crypt_global_private_key = </certs/ecprivkey.pem
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mail_crypt_global_public_key = </certs/ecpubkey.pem
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mail_crypt_save_version = 2
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}
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```
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2. Shutdown your mailserver (`docker-compose down`)
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3. You then need to [generate your global EC key](https://doc.dovecot.org/configuration_manual/mail_crypt_plugin/#ec-key). We named them `/certs/ecprivkey.pem` and `/certs/ecpubkey.pem` in step #1.
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4. The EC key needs to be available in the container. I prefer to mount a /certs directory into the container:
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```yaml
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services:
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mailserver:
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image: ghcr.io/docker-mailserver/docker-mailserver:latest
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volumes:
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. . .
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- ./certs/:/certs
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. . .
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```
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5. While you're editing the `docker-compose.yml`, add the configuration file:
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```yaml
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services:
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mailserver:
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image: ghcr.io/docker-mailserver/docker-mailserver:latest
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volumes:
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. . .
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- ./config/dovecot/10-custom.conf:/etc/dovecot/conf.d/10-custom.conf
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- ./certs/:/certs
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. . .
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```
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6. Start the container, monitor the logs for any errors, send yourself a message, and then confirm the file on disk is encrypted:
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```
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[root@ip-XXXXXXXXXX ~]# cat -A /mnt/efs-us-west-2/maildata/awesomesite.com/me/cur/1623989305.M6v<36>z<EFBFBD>@<40><> m}<7D><>,<2C><>9<EFBFBD><39><EFBFBD><EFBFBD>B*<2A>247.us-west-2.compute.inE<6E><45>\Ck*<2A>@7795,W=7947:2,
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T<>9<EFBFBD>8t<38>6<EFBFBD><36> t<><74><EFBFBD>e<EFBFBD>W<EFBFBD><57>S `<60>H<EFBFBD><48>C<EFBFBD>ڤ <20>yeY<65><59>XZ<58><5A>^<5E>d<EFBFBD>/<2F><>+<2B>A
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```
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This should be the minimum required for encryption of the mail while in storage.
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