What is the Symfony http_digest key?

Question

The use of http digest authentication in Symfony requires a 'key' property to be specified:

firewalls:
    main:         
        pattern: ^/
        anonymous: ~
        form_login: false            
        provider: fos_user_bundle
        http_digest:
            realm: "Example"
            key: "key_value_here"

I can't find any documentation for the key.

What is this key? In what way is this used? Are there any considerations I should make when choosing a value?

Answer 1

It's just a secret key, common to many encryption mechanisms.

You can re-use your application's secret (from parameters.ini), which is what I would do

key: "%secret%"