Ubuntu Manpage: borg-rcreate - Create a new, empty repository

Provided by: borgbackup2_2.0.0b8-2build2_amd64

NAME

       borg-rcreate - Create a new, empty repository

SYNOPSIS

       borg [common options] rcreate [options]

DESCRIPTION

This command creates a new, empty repository. A repository is a filesystem directory containing the
deduplicated data from zero or more archives.

Encryption mode TLDR
The encryption mode can only be configured when creating a new repository - you can neither configure it
on a per-archive basis nor change the mode of an existing repository. This example will likely NOT give
optimum performance on your machine (performance tips will come below):

borg rcreate --encryption repokey-aes-ocb

Borg will:

1. Ask you to come up with a passphrase.

2. Create a borg key (which contains some random secrets. See key_files).

3. Derive a "key encryption key" from your passphrase

4. Encrypt and sign the key with the key encryption key

5. Store the encrypted borg key inside the repository directory (in the repo config). This is why it is
essential to use a secure passphrase.

6. Encrypt and sign your backups to prevent anyone from reading or forging them unless they have the key
and know the passphrase. Make sure to keep a backup of your key outside the repository - do not lock
yourself out by "leaving your keys inside your car" (see borg_key_export). The encryption is done
locally - if you use a remote repository, the remote machine never sees your passphrase, your
unencrypted key or your unencrypted files. Chunking and id generation are also based on your key to
improve your privacy.

7. Use the key when extracting files to decrypt them and to verify that the contents of the backups have
not been accidentally or maliciously altered.

Picking a passphrase
Make sure you use a good passphrase. Not too short, not too simple. The real encryption / decryption key
is encrypted with / locked by your passphrase. If an attacker gets your key, he can't unlock and use it
without knowing the passphrase.

Be careful with special or non-ascii characters in your passphrase:

• Borg processes the passphrase as unicode (and encodes it as utf-8), so it does not have problems
dealing with even the strangest characters.

• BUT: that does not necessarily apply to your OS / VM / keyboard configuration.

So better use a long passphrase made from simple ascii chars than one that includes non-ascii stuff or
characters that are hard/impossible to enter on a different keyboard layout.

You can change your passphrase for existing repos at any time, it won't affect the encryption/decryption
key or other secrets.

Choosing an encryption mode
Depending on your hardware, hashing and crypto performance may vary widely. The easiest way to find out
about what's fastest is to run borg benchmark cpu.

repokey modes: if you want ease-of-use and "passphrase" security is good enough - the key will be stored
in the repository (in repo_dir/config).

keyfile modes: if you want "passphrase and having-the-key" security - the key will be stored in your home
directory (in ~/.config/borg/keys).

The following table is roughly sorted in order of preference, the better ones are in the upper part of
the table, in the lower part is the old and/or unsafe(r) stuff:
┌────────────────────────────┬──────────────┬────────────┬────────────────┐
│ Mode (K = keyfile or │ ID-Hash │ Encryption │ Authentication │
│ repokey) │ │ │ │
├────────────────────────────┼──────────────┼────────────┼────────────────┤
│ K-blake2-chacha20-poly1305 │ BLAKE2b │ CHACHA20 │ POLY1305 │
├────────────────────────────┼──────────────┼────────────┼────────────────┤
│ K-chacha20-poly1305 │ HMAC-SHA-256 │ CHACHA20 │ POLY1305 │
├────────────────────────────┼──────────────┼────────────┼────────────────┤
│ K-blake2-aes-ocb │ BLAKE2b │ AES256-OCB │ AES256-OCB │
├────────────────────────────┼──────────────┼────────────┼────────────────┤
│ K-aes-ocb │ HMAC-SHA-256 │ AES256-OCB │ AES256-OCB │
├────────────────────────────┼──────────────┼────────────┼────────────────┤
│ authenticated-blake2 │ BLAKE2b │ none │ BLAKE2b │
├────────────────────────────┼──────────────┼────────────┼────────────────┤
│ authenticated │ HMAC-SHA-256 │ none │ HMAC-SHA256 │
├────────────────────────────┼──────────────┼────────────┼────────────────┤
│ none │ SHA-256 │ none │ none │
└────────────────────────────┴──────────────┴────────────┴────────────────┘

none mode uses no encryption and no authentication. You're advised NOT to use this mode as it would
expose you to all sorts of issues (DoS, confidentiality, tampering, ...) in case of malicious activity in
the repository.

If you do not want to encrypt the contents of your backups, but still want to detect malicious tampering
use an authenticated mode. It's like repokey minus encryption. To normally work with authenticated
repos, you will need the passphrase, but there is an emergency workaround, see
BORG_WORKAROUNDS=authenticated_no_key docs.

Creating a related repository
You can use borg rcreate --other-repo ORIG_REPO ... to create a related repository that uses the same
secret key material as the given other/original repository.

By default, only the ID key and chunker secret will be the same (these are important for deduplication)
and the AE crypto keys will be newly generated random keys.

Optionally, if you use --copy-crypt-key you can also keep the same crypt_key (used for authenticated
encryption). Might be desired e.g. if you want to have less keys to manage.

Creating related repositories is useful e.g. if you want to use borg transfer later.

OPTIONS

       See borg-common(1) for common options of Borg commands.

   options
       --other-repo SRC_REPOSITORY
              reuse the key material from the other repository

       -e MODE, --encryption MODE
              select encryption key mode (required)

       --append-only
              create  an append-only mode repository. Note that this only affects the low level structure of the
              repository, and running delete or prune will still be allowed. See append_only_mode in  Additional
              Notes for more details.

       --storage-quota QUOTA
              Set storage quota of the new repository (e.g. 5G, 1.5T). Default: no quota.

       --make-parent-dirs
              create the parent directories of the repository directory, if they are missing.

       --copy-crypt-key
              copy  the  crypt_key  (used for authenticated encryption) from the key of the other repo (default:
              new random key).

EXAMPLES

          # Local repository
          $ export BORG_REPO=/path/to/repo
          # recommended repokey AEAD crypto modes
          $ borg rcreate --encryption=repokey-aes-ocb
          $ borg rcreate --encryption=repokey-chacha20-poly1305
          $ borg rcreate --encryption=repokey-blake2-aes-ocb
          $ borg rcreate --encryption=repokey-blake2-chacha20-poly1305
          # no encryption, not recommended
          $ borg rcreate --encryption=authenticated
          $ borg rcreate --encryption=authenticated-blake2
          $ borg rcreate --encryption=none

          # Remote repository (accesses a remote borg via ssh)
          $ export BORG_REPO=ssh://user@hostname/~/backup
          # repokey: stores the (encrypted) key into <REPO_DIR>/config
          $ borg rcreate --encryption=repokey-aes-ocb
          # keyfile: stores the (encrypted) key into ~/.config/borg/keys/
          $ borg rcreate --encryption=keyfile-aes-ocb

AUTHOR