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layout	title	parent	grand_parent	nav_order
default	File	Authentication backends	Configuration	1

File

Authelia supports a file as a users database.

Configuration

Configuring Authelia to use a file is done by specifying the path to the file in the configuration file.

authentication_backend:
    file:
        path: /var/lib/authelia/users.yml
            password_hashing:
                algorithm: argon2id
                iterations: 1
                salt_length: 16
                parallelism: 8
                memory: 1024

Password hashing configuration settings

algorithm

Value Type: String
Possible Value: argon2id and sha512
Recommended: argon2id
What it Does: Changes the hashing algorithm

iterations

Value Type: Int
Possible Value: 1 or higher for argon2id and 1000 or higher for sha512 (will automatically be set to 1000 on lower settings)
Recommended: 1 for the argon2id algorithm and 50000 for sha512
What it Does: Adjusts the number of times we run the password through the hashing algorithm

key_length

Value Type: Int
Possible Value: 16 or higher.
Recommended: 32 or higher.
What it Does: Adjusts the length of the actual hash

salt_length

Value Type: Int
Possible Value: between 2 and 16
Recommended: 16
What it Does: Adjusts the length of the random salt we add to the password, there is no reason not to set this to 16

parallelism

Value Type: Int
Possible Value: 1 or higher
Recommended: 8 or twice your CPU cores
What it Does: Sets the number of threads used for hashing

memory

Value Type: Int
Possible Value: at least 8 times the value of parallelism
Recommended: 1024‬‬ (1GB) or as much RAM as you can afford to give to hashing
What it Does: Sets the amount of RAM used in MB for hashing

Examples for specific systems

These examples have been tested against a single system to make sure they roughly take 0.5 seconds each. Your results may vary depending on individual specification and utilization, but they are a good guide to get started. You should however read How to choose the right parameters for Argon2.

System	Iterations	Parallelism	Memory
Raspberry Pi 2	1	8	64
Raspberry Pi 3	1	8	128
Raspberry Pi 4	1	8	128
Intel G5 i5 NUC	1	8	1024

Format

The format of the users file is as follows.

users:
    john:
        password: "$argon2id$v=19$m=65536,t=3,p=2$BpLnfgDsc2WD8F2q$o/vzA4myCqZZ36bUGsDY//8mKUYNZZaR0t4MFFSs+iM"
        email: john.doe@authelia.com
        groups:
            - admins
            - dev

    harry:
        password: "$argon2id$v=19$m=65536,t=3,p=2$BpLnfgDsc2WD8F2q$o/vzA4myCqZZ36bUGsDY//8mKUYNZZaR0t4MFFSs+iM"
        email: harry.potter@authelia.com
        groups: []

    bob:
        password: "$argon2id$v=19$m=65536,t=3,p=2$BpLnfgDsc2WD8F2q$o/vzA4myCqZZ36bUGsDY//8mKUYNZZaR0t4MFFSs+iM"
        email: bob.dylan@authelia.com
        groups:
            - dev

    james:
        password: "$argon2id$v=19$m=65536,t=3,p=2$BpLnfgDsc2WD8F2q$o/vzA4myCqZZ36bUGsDY//8mKUYNZZaR0t4MFFSs+iM"
        email: james.dean@authelia.com

This file should be set with read/write permissions as it could be updated by users resetting their passwords.

Passwords

The file contains hashed passwords instead of plain text passwords for security reasons.

You can use Authelia binary or docker image to generate the hash of any password. The hash-password command has many tunable options, you can view them with the authelia hash-password --help command. For example if you wanted to improve the entropy you could generate a 16 byte salt and provide it with the --salt flag. Example: authelia hash-password --salt abcdefghijklhijl. For argon2id the salt must always be valid for base64 decoding (characters a through z, A through Z, 0 through 9, and +/).

For instance to generate a hash with the docker image just run:

$ docker run authelia/authelia:latest authelia hash-password yourpassword
$ Password hash: $argon2id$v=19$m=65536$3oc26byQuSkQqksq$zM1QiTvVPrMfV6BVLs2t4gM+af5IN7euO0VB6+Q8ZFs

Full CLI Help Documentation:

Hash a password to be used in file-based users database. Default algorithm is argon2id.

Usage:
  authelia hash-password [password] [flags]

Flags:
  -h, --help              help for hash-password
  -i, --iterations int    set the number of hashing iterations (default 1)
  -k, --key-length int    [argon2id] set the key length param (default 32)
  -m, --memory int        [argon2id] set the amount of memory param (in MB) (default 1024)
  -p, --parallelism int   [argon2id] set the parallelism param (default 8)
  -s, --salt string       set the salt string
  -l, --salt-length int   set the auto-generated salt length (default 16)
  -z, --sha512            use sha512 as the algorithm (defaults iterations to 50000, change with -i)

Password hash algorithm

The default hash algorithm is salted Argon2id version 19. Argon2id is currently considered the best hashing algorithm, and in 2015 won the Password Hashing Competition. It benefits from customizable parameters allowing the cost of computing a hash to scale into the future which makes it harder to brute-force. Argon2id was implemented due to community feedback as you can see in this closed issue.

Additionally SHA512 is supported for backwards compatibility and user choice. While it's a reasonable hash function given high enough iterations, as hardware gets better it has a higher chance of being brute-forced.

Hashes are identifiable as argon2id or SHA512 by their prefix of either $argon2id$ and $6$ respectively, as described in this wiki page.

Password hash algorithm tuning

All algorithm tuning is supported for Argon2id. The only configuration variables that affect SHA512 are iterations and salt length. The configuration variables are unique to the file authentication provider, thus they all exist in a key under the file authentication configuration key called password_hashing. We have set what are considered as sane and recommended defaults to cater for a reasonable system, if you're unsure about which settings to tune, please see the parameters above, or for a more in depth understanding see the referenced documentation.

Argon2 Links

How to choose the right parameters for Argon2

Go Documentation

IETF Draft

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