aah Authentication

Since v0.7 Authentication is the process of identity verification – you are trying to prove a user is who they say they are. To do so, a user needs to provide some sort of proof of identity that your system understands and trust.

Familiarize yourself with aah framework security Terminology, Design and Permissions.

Table of Contents

Terminology you’ll need

  • Subject - Security specific user ‘view’ of an application user. It can be a human being, a third-party process, a server connecting to you application application, or even a cron job. Basically, it is anything or anyone communicating with your application.
  • Principals - A subjects identifying attributes. First name, last name, social security number, username.
  • Credential - secret data that are used to verify identities. Passwords, x509 certificates, etc.
  • Authenticator - An application implements the interface authc.Authenticator to provide authentication information to framework

How to: Authentication in aah framework

By nature of aah security implementation, you can have one or more Auth Scheme defined and can be mapped in the routes.conf per route basis.

  • Choose your auth schemes and configure in security.conf, out-of-the-box framework supports - Form-based Auth - Basic Auth - Generic Auth - it has many possibilities such as JWT, OAuth, etc.
  • Implement authc.Authenticator interface, aah recommends the package name as security
  • Configure auth related settings in routes.conf
  • For Authorization refer to authorization guide

Security Tip:

Security best practice is to give generic login failure messages to users because you do not want to aid an attacker trying to break into your system.

How to: Check Subject is Authenticated in view/template

aah provides function isauthenticated to check whether subject is authenticated or not.

{{ if isauthenticated . }}
<a href="/logout">Logout</a>
{{ end }}

Know more about authorization template funcs here.

Auth Schemes

Auth schemes are configured in security.conf and you can define one or more auth schemes. Configuration goes under-

security {
  auth_schemes {
    ...
  }
}

Form-based Auth

aah provides easy to use form-based auth. Following is the configuration. You have to implement authc.Authenticator and authz.Authorizer then register it the config. Refer to Tutorial - Form-based Auth

security {
  auth_schemes {
    # HTTP Form Auth Scheme
    # It is custom defined name, this is used in the routes `auth` attribute.
    form_auth {
      # Auth scheme name.
      # Supported values are `form`, `basic` and `generic`.
      # It is required value, no default.
      scheme = "form"

      # Framework calls `Authenticator` to get the Subject's authentication
      # information. Then framework validates the credential using password
      # encoder.
      # It is required value, no default.
      authenticator = "security/AuthenticationProvider"

      # Framework calls `Authorizer` to get Subject's authorization information,
      # such as Roles, Permissions. Then it populates the Subject instance.
      # It is required value, no default.
      authorizer = "security/AuthorizationProvider"

      # Password encoder is used to encode the given credential and then compares
      # it with application provide credential.
      # Doc: https://docs.aahframework.org/password-encoders.html
      # Default value is `bcrypt`.
      #password_encoder = "bcrypt"

      # Field names are used to extract `AuthenticationToken` from request.
      field {
        # Default value is `username`
        #identity = "username"

        # Default value is `password`
        #credential = "password"
      }

      # URLs is used when appropriate.
      url {
        # Login page URL, implement your login and configure here.
        # Default value is `/login.html`.
        #login = "/login.html"

        # Login submit URL, used to submit login credential for authentication.
        # Basically login form submits its values to this URL as POST request.
        # Default value is `/login`.
        #login_submit = "/login"

        # Login failure, any failure during authentication process. Framework
        # sends user to this URL and logs detailed information in the log.
        #login_failure = "/login.html?error=true"

        # Default page URL after the successful authentication. By default framework
        # redirects the user to requested page after authentication. Otherwise it
        # sends to this URL.
        # Default value is `/`.
        #default_target = "/"

        # Always redirect to default URL, regardless of the request page.
        # Default value is `false`.
        #always_to_default = false
      }
    }
  }
}

Configure login submit URL as virtual route

You have to configure login submit URL as Virtual routes in the routes.conf.

login_submit {
  path ="/login"
  method = "POST"
  controller = "VirtualFormController"
}

Logout Subject

To logout the subject/user from application is as follows. It clear all the subject values and session.

ctx.Subject().Logout()

Basic Auth

aah framework supports basic auth in two ways. You can use either one.

  • Using File realm - This is good for when you have known set of users, roles and permissions (roles and permissions are optional though).
  • Dynamic way implementing interface authc.Authenticator and authz.Authorizer

Refer to Tutorial - REST API Basic Auth. You can doing for web app too for certain routes. This is an example for REST API application.

security {
  auth_schemes {
    # HTTP Basic Auth Scheme
    # It is custom defined name, this is used in the routes `auth` attribute.
    basic_auth {
      # Auth scheme name.
      # Supported values are `form`, `basic` and `generic`.
      # It is required value, no default.
      scheme = "basic"

      # Realm name is used for `Www-Authenticate` HTTP header.
      # Note: Modern browsers are not respecting this values now a days.
      # However aah framework does its due diligence.
      realm_name = "Protected"

      # Basic auth realm file path. You can use absolute path or
      # environment variable to provide path.
      # No default value.
      file_realm = "/path/to/basic-realm-file.conf"

      ## NOTE: you can use either file realm or dynamic

      # Framework calls `Authenticator` to get the Subject's authentication
      # information. Then framework validates the credential using password
      # encoder.
      # It is required value when `file_realm` not configured, no default.
      authenticator = "security/AuthenticationProvider"

      # Framework calls `Authorizer` to get Subject's authorization information,
      # such as Roles and Permissions. Then it populates the Subject instance.
      # It is required value when `file_realm` not configured, no default.
      authorizer = "security/AuthorizationProvider"

      # Password encoder is used to encode the given credential and then compares
      # it with application provide credential.
      # Doc: https://docs.aahframework.org/password-encoders.html
      # Default value is `bcrypt`.
      #password_encoder = "bcrypt"
    }
  }
}

Basic Auth - File Realm format

Repeat this configuration block/section for every user. Roles and Permissions is optional one.

<username> {
  # Password is require value.
  password = "$2y$10$2A4GsJ6SmLAMvDe8XmTam.MSkKojdobBVJfIU7GiyoM.lWt.XV3H6"

  # Roles attribute is optional value.
  roles = ["role1","role2"]

  # Permissions attribute is optional value.
  permissions = [
    "permission1",
    "permission2",
  ]
}

For example:

jeeva {
  password = "$2y$10$2A4GsJ6SmLAMvDe8XmTam.MSkKojdobBVJfIU7GiyoM.lWt.XV3H6"
  roles = ["admin", "supervisor"]
  permissions = [
    "newsletter:read,write"
  ]
}

mark {
  password = "$2y$10$2A4GsJ6SmLAMvDe8XmTam.MSkKojdobBVJfIU7GiyoM.lWt.XV3H6"
}

Generic Auth

Note:

Generic auth has more possibilities, so credential validation is not done by framework. That is left up to you on authc.Authenticator implementation. It's kept open for extensions such as JWT, OAuth, etc.

For example: Authenticator is responsible for credential validation and return authc.AuthenticationInfo to the framework. If subject doesn’t exist or credential doesn’t match, it returns appropriate error such as authc.ErrAuthenticationFailed or authc.ErrSubjectNotExists; then framework responds caller with 401 Unauthorized.

security {
  auth_schemes {
    # Generic Auth Scheme
    # It is custom defined name, this is used in the routes `auth` attribute.
    generic_auth {
      # Auth scheme name.
      # Currently supported values are `form`, `basic` and `generic`.
      # It is required value, no default.
      scheme = "generic"

      # Framework calls `Authenticator` to get the Subject's authentication
      # information. The credential validation is not done by framework, it is
      # left to interface implementation.
      # It is required value, no default.
      #authenticator = "security/AuthenticationProvider"

      # Framework calls `Authorizer` to get Subject's authorization information,
      # such as Roles and Permissions. Then it populates the Subject instance.
      # It is required value, no default.
      #authorizer = "security/AuthorizationProvider"

      # Header names are used to extract `AuthenticationToken` from request.
      header {
        # Default value is 'Authorization'
        #identity = "Authorization"

        # Optional credential header
        # Typically it's not used, however in the industry people do use it
        # Default value is empty string
        #credential = "X-AuthPass"
      }
    }
  }
}

  Need Help?

  •   Chat on Gitter
  •   Github Issues
  •   Ask on StackOverflow - tag aahframework