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 # backups
 
-Auto backup script
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+Auto backup script. The objectives are the following:
+- Have a raspberry-pi `RPI` (or any other device) doing automatic backups of a remote server `SERVER` every day
+- Backups are incremental, without redundancy, it is easy to get data out of a specific snapshot
+- `RPI` is not vulnerable to physical access (in a reasonable way):
+    + The backup disk is encrypted, but the key is not stored on `RPI`
+    + The keys to access `SERVER` are locked and can be "revoked at distance"
+- Conversely, if a malicious access is made to `SERVER`, backups are not compromised
+- If a backup fails for any reason, a notification is sent (via Discord)
+- `RPI` can be accessed remotely, without needing to expose one of its ports
+
+## Installation
+
+On a raspbian distribution, this requires:
+- The packages `cryptsetup sshpass`
+- a filesystem (in a LUKS device with `LUKS_KEY`) formatted in xfs or btrf (needs either `xfsprogs` or `btrfs-progs`)
+- an ssh key locked with `SSH_PASSPHRASE` to access to the server to backup
+- Two urls containing each `LUKS_KEY` or `SSH_PASSPHRASE`
+- a (Discord) webhook
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