Note: This security entry has been retired since v2.3.0, and totally reimplemented in v3.0
In gui.config we have a function that allows to show unencrypted values of the yaml config file While this is practical, it should never be allowed on non compiled builds or with the default backup admin password

All these commands are run with npbackup held privileges. In order to avoid a potential attack, the config file has to be world readable only.

Password command is encrypted in order to avoid it's divulgation if config file is world readable. Password command is also not logged.

Partially covered with password_command feature, and alternative aes key management. We should have a central password server that holds repo passwords, so password is never actually stored in config. This will prevent local backups, so we need to think of a better zero knowledge strategy here.

Since viewer mode requires actual knowledge of repo URI and repo password, there's no need to manage local permissions. Viewer mode permissions are set to "restore".

Since v3.0.0, we insert permissions directly into the encrypted repo URI. Hence, update permissions should only happen in two cases:

• CLI: Recreate repo_uri entry and add permission field from YAML file
• GUI: Enter permission password to update permissions

Since encryption is symmetric, we need to protect our sensible data. Best ways:

• Compile with alternative aes-key
• Use NPBACKUP_KEY_LOCATION or NPBACKUP_KEY_COMMAND to specify alternative AES keys

Using --show-config should hide sensible data, and manager password.

When using --show-config or right click show unecrypted, we should only show unencrypted config if password is set.
Environment variable NPBACKUP_MANAGER_PASSWORD will be read to verify access, or GUI may ask for password. Also, when wrong password is entered, we should wait in order to reduce brute force attacks.

When using retention policies, we need to make sure that current system date is good, in order to avoid wrong retention deletions.
When set, an external NTP server is used to get the offset. If offset is high enough (10 min), we avoid executing the retention policies.

Using obfuscation() symmetric function in order to not store the bare AES key.

The PRIVATE directory might contain alternative AES keys and obfuscation functions which should never be bundled for a PyPI release.