# Databases

Authentication | Users | Password
--- | --- | ---
✔ | ✔ | ✔

## Presentation

### Drivers

LL::NG can use a lot of databases as authentication, users and password backend:

- MariaDB/MySQL
- PostGreSQL
- Oracle
- ...

Indeed, any Perl DBD driver can be used.

### Schema

LL::NG can use two tables:

- Authentication table: where login and password are stored
- User table: where user data are stored (mail, name, etc.)

Authentication table and user table can be the same.

The password can be in plain text, or encoded with a standard SQL method:

- SHA
- SHA1
- MD5

#### Example 1: two tables

##### Authentication table

id | login | password
--- | --- | ---
0 | coudot | 1f777a6581e478499f4284e54fe2d4a4e513dfff
1 | xguimard | a15a18c8bb17e6f67886a9af1898c018b9f5a072
2 | tchemineau | 1f777a6581e478499f4284e54fe2d4a4e513dfff

##### User table

id | user | name | mail
--- | --- | --- | ---
0 | coudot | Clément OUDOT | coudot@example.com
1 | tchemineau | Thomas CHEMINEAU | tchemineau@example.com
2 | xguimard | Xavier GUIMARD | xguimard@example.com

#### Example 2: single table

id | user | password | name | mail
--- | --- | --- | --- | ---
0 | coudot | 1f777a6581e478499f4284e54fe2d4a4e513dfff | Clément OUDOT | coudot@example.com
1 | tchemineau | 1f777a6581e478499f4284e54fe2d4a4e513dfff | Thomas CHEMINEAU | tchemineau@example.com
2 | xguimard | a15a18c8bb17e6f67886a9af1898c018b9f5a072 | Xavier GUIMARD | xguimard@example.com

### SQL

LL::NG will operate some SQL queries:

- Authentication: select row in authentication table matching user and password
- Search user: select row in user table matching user
- Change password: update password column in authentication table matching user

## Configuration

In Manager, go in `General Parameters` > `Authentication modules` and choose Database (DBI) for authentication, users and/or password modules.

### Authentication level

The authentication level given to users authenticated with this module.

As DBI is a login/password based module, the authentication level can be:

- increased (+1) if portal is protected by SSL (HTTPS)
- decreased (-1) if the portal autocompletion is allowed (see portal customization)

### Exported variables

List of columns to query to fill user session. See also exported variables configuration.

### Connection

Connection settings can be configured differently for authentication process and user process. This allows one to use different databases for these process. By default, if user process connection settings are empty, authentication process connection settings will be used.

- Chain: DBI chain, including database driver name and database name (for example: dbi:mysql:database=lemonldapng;host=localhost).
- User: Connection user
- Password: Connection password

### Schema

- Authentication table: authentication table name
- User table: user table name
- Login field name: name of authentication table column hosting login
- Password field name: name of authentication table column hosting password
- Mail field name: name of authentication table column hosting mail (for password reset)
- Login field name in user table: name of user table column hosting login

### Password

- Hash schema: SQL method for hashing password. Can be left blank for plain text passwords.
- Dynamic hash activation: Activate dynamic hashing. With dynamic hashing, the hash scheme is recovered from the user password in the database during authentication.
- Supported non-salted schemes: List of whitespace separated hash schemes. Every hash scheme MUST match a non-salted hash function in the database. LemonLDAP::NG relies on this hashing function for computing user password hashes. These hashes MUST NOT be salted (no random data used in conjunction with the password).
- Supported salted schemes: List of whitespace separated salted hash schemes, of the form "sscheme", where scheme MUST match a non-salted hash function in the database. LemonLDAP::NG relies on this hashing function for computing user password hashes. Salted and non-salted scheme lists are not necessarily equivalent. (for example: non-salted="sha256" and salted="ssha ssha512" is valid)
- Dynamic hash scheme for new passwords: LemonLDAP::NG is able to store new passwords in the database (while modifying or reinitializing the password). You can choose a salted or non salted dynamic hashed password. The value must be an element of "Supported non-salted schemes" or "Supported salted schemes".

The SQL function MUST have hexadecimal values as input AND output
Here is an example for creating a postgreSQL SHA256 function. 1. Install postgresql-contrib. 2. Activate extension:

    CREATE EXTENSION pgcrypto;

3. Create the hash function:

    CREATE OR REPLACE FUNCTION sha256(varchar) returns text AS $$
    SELECT encode(digest(decode($1, 'hex'), 'sha256'), 'hex')
    $$ LANGUAGE SQL STRICT IMMUTABLE;