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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:
  disable_reset_password: false
  file:
    path: /config/users.yml
    password:
      algorithm: argon2id
      iterations: 1
      salt_length: 16
      parallelism: 8
      memory: 64

Format

The format of the users file is as follows.

users:
  john:
    displayname: "John Doe"
    password: "$argon2id$v=19$m=65536,t=3,p=2$BpLnfgDsc2WD8F2q$o/vzA4myCqZZ36bUGsDY//8mKUYNZZaR0t4MFFSs+iM"
    email: [email protected]
    groups:
      - admins
      - dev
  harry:
    displayname: "Harry Potter"
    password: "$argon2id$v=19$m=65536,t=3,p=2$BpLnfgDsc2WD8F2q$o/vzA4myCqZZ36bUGsDY//8mKUYNZZaR0t4MFFSs+iM"
    email: [email protected]
    groups: []
  bob:
    displayname: "Bob Dylan"
    password: "$argon2id$v=19$m=65536,t=3,p=2$BpLnfgDsc2WD8F2q$o/vzA4myCqZZ36bUGsDY//8mKUYNZZaR0t4MFFSs+iM"
    email: [email protected]
    groups:
      - dev
  james:
    displayname: "James Dean"
    password: "$argon2id$v=19$m=65536,t=3,p=2$BpLnfgDsc2WD8F2q$o/vzA4myCqZZ36bUGsDY//8mKUYNZZaR0t4MFFSs+iM"
    email: [email protected]

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

Options

path

type: string (path)

required: yes

password

algorithm

type: string

default: argon2id

required: no

Controls the hashing algorithm used for hashing new passwords. Value must be one of argon2id or `sha512.

iterations

type: integer

required: no

Controls the number of hashing iterations done by the other hashing settings.

When using argon2id the minimum is 1, which is also the recommended value.

When using sha512 the minimum is 1000, and 50000 is the recommended value.

salt_length

type: integer

default: 16

required: no

Controls the length of the random salt added to each password before hashing. It’s recommended this value is set to 16, and there is no documented reason why you’d set it to anything other than this, however the minimum is 8.

parallelism

type: integer

default: 8

required: no

This setting is specific to argon2id and unused with sha512. Sets the number of threads used when hashing passwords, which affects the effective cost of hashing.

memory

This setting is specific to argon2id and unused with sha512. Sets the amount of memory allocated to a single password hashing action. This memory is released by go after the hashing process completes, however the operating system may not reclaim it until it needs the memory which may make Authelia appear to be using more memory than it technically is.

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 +/).

Passwords passed to hash-password should be single quoted if using special characters to prevent parameter substitution. 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 64)
  -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 Argon2id version 19 with a salt. 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.

For backwards compatibility and user choice support for the SHA512 algorithm is still available. While it’s a reasonable hashing function given high enough iterations, as hardware improves 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.

Important Note: When using argon2id Authelia will appear to remain using the memory allocated to creating the hash. This is due to how Go allocates memory to the heap when generating an argon2id hash. Go periodically garbage collects the heap, however this doesn’t remove the memory allocation, it keeps it allocated even though it’s technically unused. Under memory pressure the unused allocated memory will be reclaimed by the operating system, you can test this on linux with:

$ stress-ng --vm-bytes $(awk '/MemFree/{printf "%d\n", $2 * 0.9;}' < /proc/meminfo)k --vm-keep -m 1

If this is not desirable we recommend investigating the following options in order of most to least secure:

  1. using the LDAP authentication provider
  2. adjusting the memory parameter
  3. changing the algorithm

Password hash algorithm tuning

All algorithm tuning for Argon2id is supported. 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. 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 below, or for a more in depth understanding see the referenced documentation in Argon2 links.

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 the linked documents in Argon2 links.

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

How to choose the right parameters for Argon2

Go Documentation

IETF Draft