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Auth concepts

This page describes basic concepts and glossary commonly referred to when working with authentication and authorization.

Most of the documentation later on assumes that you are familiar with these concepts, so come back when you stumble upon something you're unfamiliar with.


Protocols

OAuth 2.0

OAuth 2.0 is an industry-standard protocol for authorization.

In NAV, the protocol is used to acquire security tokens for use in authenticated requests between applications.

To obtain an access token, we need an authorization grant. The grant represents a delegated authorization. The client application is granted authorization by a resource owner (such as an end user or the client itself) to access protected resources that belong to the owner.

There are multiple ways of obtaining such a grant, depending on the use case:

Internal applications

Employee-facing applications

External applications

Citizen-facing applications

OpenID Connect

OpenID Connect (OIDC) is an identity layer on top of the OAuth 2.0 protocol. It is used to authenticate end users.

The platform provides opt-in login proxies that implement OpenID Connect:

Due to the complexity involved in implementing and maintaining such clients, we recommend that your applications use these proxies when possible.

If you do implement your own client, we recommend that you always use the Authorization Code Flow together with the OAuth 2.0 - Proof Key for Code Exchange (PKCE) extension.


Actors

Typical actors involved in OAuth 2.0 grants and OpenID Connect flows.

Identity Provider

An identity provider (IdP) is a common service that NAV delegates to for authentication of end-users and/or services. Similar terms such as authorization server (AS) or OpenID provider (OP) are used interchangeably with IdP.

Providers that the platform supports provisioning for:

Well-Known URL / Metadata Document

Every identity provider will have a metadata document that allows clients to discover the provider's capabilities and endpoints.

This is also referred to as the Discovery Endpoint or Metadata Document Endpoint or other variations with similar names.

The well-known URL points to this document, which has a registered suffix under the /.well-known path. For example:

  • https://as.example.com/.well-known/openid-configuration
  • https://as.example.com/.well-known/oauth-authorization-server

The platform provides these URLs for you at runtime.

Metadata Document

A metadata document can look like the one shown below. Not all fields are present or required depending on whether the provider supports the OAuth 2.0 or the OpenID Connect specifications.

{
  "issuer": "https://as.example.com",
  "authorization_endpoint": "https://as.example.com/authorize",
  "token_endpoint": "https://as.example.com/token",
  "end_session_endpoint": "https://as.example.com/endsession",
  "jwks_uri": "https://as.example.com/jwk",
  "response_types_supported": [
    "code",
    "id_token",
    "id_token token",
    "token"
  ],
  "response_modes_supported": [
    "query",
    "form_post",
    "fragment"
  ],
  "id_token_signing_alg_values_supported": [
    "RS256"
  ],
  "code_challenge_methods_supported": [
    "S256"
  ],
  "token_endpoint_auth_methods_supported": [
    "private_key_jwt"
  ]
}

Issuer

The issuer property defines the identifier for the provider. This identifier must be a URL that uses the "https" scheme and without query or fragment components.

Any JWT issued by the provider must contain a iss claim with a value that is exactly equal to the value found in the issuer property of the metadata document. This should be validated by OpenID Connect clients and resource servers.

Additionally, the issuer value should be equal to the well-known URL when appending the appropriate well-known suffix. For the examples above, the issuer would be https://as.example.com.

Token Endpoint

The token_endpoint property points to the endpoint where your client can request tokens from the provider. The provider will issue and respond with tokens as defined in RFC 6749, Section 5.1.

Tokens have a set expiration time, indicated by the expires_in field in the token response. The tokens returned are thus suitable for caching and re-use within this period.

JWKS Endpoint (Public Keys)

The jwks_uri property points to the endpoint where the provider's public JWKs are published. Your client uses these public keys to validate the signature for any JWT issued by the provider.

Most clients implement a form of caching for these keys. A reasonable refresh frequency for the cache is usually somewhere between 1 hour to 24 hours.

Do note that the set of keys may change at any time, e.g. during revocation or rotation of keys. Most libraries usually handle changes to these keys transparently for you.

Resource Server

A resource server is any entity that requires requests to be authenticated before responding with meaningful data. In other words, this is your standard bread-and-butter API server.

Resource servers should require that requests to sensitive endpoints are authenticated with a Bearer token. The server should validate tokens for such requests before accepting or rejecting the request.

Client

A client or application is any entity or device that needs to obtain a token to access a resource server.

Tokens are acquired when the client as a part of the OAuth 2.0 grants or OpenID Connect flows.

There are two types of clients that these specifications define; public and confidential. The primary difference here is the notion of whether the client is capable of keeping secrets.

A public client cannot use secrets due to the nature of their runtime environment, such as directly in a browser (in a single-page application) or on a mobile device.

A confidential client can authenticate with an identity provider using a secret or private key due to the secrets being difficult to access to other entities than the client itself. Backend APIs, backend-for-frontends (BFFs) or standalone daemons are typical examples of confidential clients.

Unless specified otherwise, all clients we use are confidential clients.

Client ID

A client ID is a unique identifier associated with your client for a given identity provider. The value of the identifier is generally not considered to be confidential.

The client ID for your client is injected at runtime as an environment variable. See the respective identity provider page for details:

Client Authentication

A confidential client must authenticate itself to the identity provider.

Client Secret

A client secret is a password that belongs to a given client.

This is used to authenticate the client when attempting to acquire tokens from the identity provider.

Entra ID is the only identity provider we use that supports the client_secret_post authentication method. The secret itself is passed in plain-text as part of the request body:

POST /token HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded

client_id=<some-client-id>
&client_secret=<some-client-secret>
&grant_type=client_credentials

As the platform rotates these credentials relatively regularly, using the client_secret_post method shouldn't pose as a significant security risk.

Client Assertion

A client assertion is a JWT that can be used to authenticate a client. Your client must create the assertion and sign it using a private key associated with the client. The JWT assertion will look something like this (in its decoded form):

Header:

{
  "alg": "RS256",
  "typ": "JWT",
  "kid": "<key identifier for private key>"
}

Payload:

{
  "aud": "https://as.example.com/token",
  "iss": "<your-client-id>",
  "jti": "<some-uuid>",
  "iat": 1520589808,
  "nbf": 1520589808,
  "exp": 1520589928
}

This method of authentication (also known as the private_key_jwt method) is supported by all identity providers we use. It is also mandatory for all our clients across all the providers, except Entra ID.

An assertion has several security advantages over a client secret:

  • The client's private key is never exposed or sent as part of a request
  • The assertion itself is usually only valid for a short duration - meaning that the blast radius is limited if the assertion is intercepted or stolen during transport
  • The provider only needs knowledge of the public key to verify the assertion when receiving an authenticated request from the client. The platform takes care of generating and registering the public key.

For example, for the client credentials grant:

POST /token HTTP/1.1
Host: as.example.com
Content-Type: application/x-www-form-urlencoded

grant_type=client_credentials
&client_id=<some-client-id>
&client_assertion=eyJhbGciOiJFUzI1NiIsImtpZCI6IjE2In0.
eyJpc3Mi[...omitted for brevity...].
J9l-ZhwP[...omitted for brevity...]
&client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer

Each identity provider may have different requirements for the grant_type and parameter names for the assertions (e.g. assertion vs client_assertion), so make sure to consult the documentation for the specific provider you're using.


Tokens

A token is a piece of data that contains information about an authenticated entity. The receiver of a token can assert claims about the entity that the request is performed on behalf of.

An advantage of using a token is that a user never has to directly present their private credentials or passwords to the resource server. This is delegated to the identity provider who in turn issues tokens for said user. Additionally, a token often has an expiry time to limit its use.

A token is usually in the form of a self-contained JWT, but can have other formats. All JWTs are tokens, but not all tokens are JWTs.

Bearer Token

A token is generally used as a Bearer token. Most resource servers in NAV will require that you supply the bearer token in the Authorization header, as specified in RFC 6750, section 2.1:

GET /resource HTTP/1.1

Host: as.example.com
Authorization: Bearer eyJhbGciOiJFUzI1NiIsImtpZCI6IjE2In0...

JWT

JSON Web Token (JWT) is a compact, self-contained means of representing claims as a JSON object to be transferred between two parties, as specified in RFC 7519.

The contained claims can be verified and trusted by validating its digital signature.

In most cases, the JWT is signed using an asymmetric secret, i.e. public and private key pair:

  1. The sending party will sign the JWT using their private key.
  2. The receiving party may verify the signature using the signer's associated public key, which may be distributed out-of-band or published at a well-known endpoint.

A JWT will look something like this in its serialized, compact form (where each part is base64-URL-encoded):

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

The token consists of three parts:

<header>.<payload>.<signature>

The header consists of metadata describing the token, such as:

  • kid: The key ID of the associated key used to sign the token.
  • typ: The type of token, usually JWT.
  • alg: The algorithm used to sign the token, usually RS256.

Example:

{
  "alg": "RS256",
  "typ": "JWT",
  "kid": "<some-key-id>"
}

Payload

The payload contains claims about the associated user or principal that the token represents as well as additional data.

JWTs will mostly consist of registered claims or "standard" claims. Depending on the identity provider however, additional claims may be included.

Example (with registered claims only):

{
  "iss": "https://as.example.com",
  "sub": "f6V1gB18pwpV06nWjbPLMxdjZiefEnl7G5oNih6LDUI=",
  "aud": "302fc528-9d76-481a-bd4f-92a540d738c8",
  "nbf": 1648645430,
  "iat": 1648645430,
  "exp": 1648649030,
  "jti": "W1bYOUA0WT1rEYUjE2YfXge0cfVSgiE5sSwIMM4tSSA"
}

See RFC 7519, section 4.1 for descriptions of these claims.

Parties receiving JWTs should validate the claims found in the payload. See token validation.

Signature

A JWT should always be signed by its issuer using their private key.

Recipients of the JWT can use the signature to verify the integrity of the information contained within the token. The issuer's public key is used to verify the signature. Successful verification implies that the token nor its contents has been tampered with or modified at any point after being issued.

The signature is generated by encoding the header and payload, generating a hash of the encoded data, and then signing the hash using the issuer's private key.

ID Token

An ID token is only included as part of the OpenID Connect standard and is always a JWT. The ID token is strictly used for authentication of end-users.

It should not be used to grant access to any resource servers. The correct token to use in such cases is an access token.

The ID token only asserts that a user has been logged in at the identity provider and authenticated. The token's intended recipient is the client application that initiated the login.

Access Token

An access token is a token that allows the client application to perform authenticated requests on behalf of the end-user. In OAuth 2.0 terms, this is what is known as delegated authorization.

The token should be used when performing requests to a resource server, and the resource server should validate the token.

Access tokens are usually in the form of JWTs, which allows for local validation without the need for network calls.

Token Validation

There are two distinct cases where your client should perform token validation:

  1. Your application is a resource server or API that receives authenticated requests from consumers.
  2. Your application performs the OpenID Connect Authorization Code Flow.

Validation should always be performed before granting access to any resource server.

Use well-known and widely used libraries and frameworks that take care of most of the heavy lifting for you.

See libraries and frameworks for a non-comprehensive list.

Signature Validation

A JWT usually contains the kid (key ID) claim in the token's header to indicate which key was used to sign the token. The signature can then be verified by finding the matching public key from the provider's jwks_uri endpoint.

The algorithm used to sign a JWT is indicated by the alg claim in the token's header. For our providers, the algorithm value should be RS256. If the algorithm is set to none or the JWT is not signed, the request should be rejected.

Claims Validation

Generally speaking, the most important JWT claims to validate are the following:

  • iss (issuer)
    • The issuer of the token. This should be exactly equal to the issuer property declared by the provider's metadata document
  • aud (audience)
    • The expected recipient of the token.
    • The value of this is usually a unique identifier such as a client ID that belongs to either the client or resource server that the token is intended for.
  • exp (expiration time)
    • The timestamp for which the token expires, in unix time (seconds since epoch). The token is invalid if it is used after this time.
  • iat (issued at time)
    • The timestamp for which the token was issued, in unix time (seconds since epoch). This can be used to determine the age of the token.
  • nbf (not before time)
    • The timestamp for which the token is considered valid, in unix time (seconds since epoch). The token is invalid if it is used before this time.
    • This is an optional claim and not always included depending on the provider, but should be validated if present.

If any of the above claims are missing or contain unexpected values, validation should fail and the token should be rejected. Most libraries will have implementations to automatically validate these de facto standard claims.

See the individual identity provider pages for specific validation related to each provider:


Cryptography

Tokens are often signed using public-key cryptography, or asymmetric cryptography. This usually involves having a pair of private and public keys.

One party keeps the private key secret, while the associated public key can be freely distributed to other parties. This public key can be used to verify that any data signed with the private key indeed was signed by a party that possesses the private key.

JWK

A JSON Web Key (JWK) is a cryptographic key represented as a JSON object.

A JWKS (JWK Set) is a closely related term. It is a set of keys that may contain multiple JWKs.

Private Keys

If your application integrates with one of the identity providers in use at NAV, you will have a unique private key for each combination of (client, identity provider).

The private key should be, as its name implies, private. It is considered to be a secret in line with passwords and other sensitive keys. It should never be exposed to the browser, an end-user, or committed to version control.

This private key is primarily meant to be used in client assertions where your client authenticates itself with a JWT that is signed with said key.

Private JWK (click to expand)
  {
     "p": "2dZeNRmZow7uWKzqpOolNf7FUIr6dP5bThwnqpcDca7sP96fzPGaryZmYAawZj7h1UthpDp9b2D5v0-D0fSrbdp-MisaOz_ZL-2kdwyTSIP0ii-4yPHpFqaZuGTbuLmROwDhklTGMoYC4fN8vb0jgE6cR33bA52JH255qz5R1rc",
     "kty": "RSA",
     "q": "pIt7sgMqDPGZDMiksZ19R9iuUZk5ZcsnPeI0yAGIaEp75Nc7IH9F1LQ8mPw-wtV3Yde26mByszjeskVfldlReZmzeCTXq4jgu5WEi2GM7craTZj-ES7SLkuP21uvbgxGCLxEizr4RCdZD8TtkxcSG2-GPkp-N4IX9187kvWbWl8",
     "d": "R_P82iKNJflwkPnpOr5eGmtekLvTq1cZwJ7M0vbox3LlVmpIP9iRPKVEwuBva0ybRu1pkvM4S3DFgYK6gKjHVzPYl6lHvKZxbFyP8lJoaj1km2NhA3cwqJjqkx4VAJhLlEuG5wDlTSRXNpzqfamdZcH-XMG2rM-nh6yFqbSzyaeO99ZnGMDp5mZvzGuR0VmV6IXPXqelP4uT9cPQD60h1v2DaOKlmd-0ghGfdHa0hzR5S8C55oZ5hF1_bhgx6tA8VzC1jp41mDbKmKAOKvcFG2T9JQRBml2izRVVaCsVN0_ZCR7NhQYrkreqgVN_ZLlgzI6YSA2EN1FWmc9GvNFAbQ",
     "e": "AQAB",
     "use": "sig",
     "kid": "ut-Fle8JH9IdPqo7QDDakblWR1DdvMIijJT9A-lVntk",
     "qi": "uoncSFVC9_vS652rNSZQO8I7KCk0b2bpt38Sb1iQ8Vha5lYkrTp-AsZLoduj7TscCCqlftm9R-FkfERjEYZLdPKQIaGcCQ-L0RzIG_K3w48Tk2T_EEiMqds4UeBpQxccMjUvX-t_b7pwMjFL1RIEBSWAxg5YShT8C83hv0llh9Y",
     "dp": "BLMxWSfyPqhl0Bf7AA_lOaMDktdMzBVo1uiYmn-jnWJOypn9DKjx03Gap9u9Fpeou7dipe51ImAPQ2dtyqvivv4F1wNDD6AzCWuxLrhgvSHLtueMrxk5FDoH-wiCDRxD2-gK9eNKW3C0wzdDq7xW9b-8c3ZtsUhG2xzBF0bC8UU",
     "alg": "RS256",
     "dq": "R_ji4BhWOlcq9NaGg1I5zEVQ6kw1OPtFbOIW6C0Td1qtGomySSKibslvgBNFeH9auqdaUOZjBVWowx1pE-h8pM3AHJsw4sz6T9K0qSrAM_r4xdxXtThfovRWNkLCV0ZzE7sV2DixA06avDUNHbuHpgyAEZsP3kO_K-qx6jQYAc0",
     "n": "jAQFAKQ9omNtb_I2iSryCulJnkB56qGf35fA1RrDBLup7ysJCez9dnu-HTZ62SKoe-9Pxu-4WzjjBNQacotUXYTIi7GFWM5Pyb4ha-bBJprbiwhyrYGIVzZw4LIcleexWPcIOI0cTKmpM6qKb9_6CTFa-A6uX_16n-n3fQjWGPKrJBY7mcIalJ4YTmLhavs6yt6efSD67SaJ2FabzjouRa_yeDmsGPq2LA-4FymDvuGCHeeMtPO9ClnA2eWC15L7n3-Pagm5pso5GchORl2Rwr_bhCmNCKsC_Qh6TqTHJyymuJwZIuSOv88cf-5UsSidRSJ9r0dBl0S0KgndCagD6Q"
  }
Private JWKS / JWK Set (click to expand)
  {
    "keys": [
       {
           "p": "2dZeNRmZow7uWKzqpOolNf7FUIr6dP5bThwnqpcDca7sP96fzPGaryZmYAawZj7h1UthpDp9b2D5v0-D0fSrbdp-MisaOz_ZL-2kdwyTSIP0ii-4yPHpFqaZuGTbuLmROwDhklTGMoYC4fN8vb0jgE6cR33bA52JH255qz5R1rc",
           "kty": "RSA",
           "q": "pIt7sgMqDPGZDMiksZ19R9iuUZk5ZcsnPeI0yAGIaEp75Nc7IH9F1LQ8mPw-wtV3Yde26mByszjeskVfldlReZmzeCTXq4jgu5WEi2GM7craTZj-ES7SLkuP21uvbgxGCLxEizr4RCdZD8TtkxcSG2-GPkp-N4IX9187kvWbWl8",
           "d": "R_P82iKNJflwkPnpOr5eGmtekLvTq1cZwJ7M0vbox3LlVmpIP9iRPKVEwuBva0ybRu1pkvM4S3DFgYK6gKjHVzPYl6lHvKZxbFyP8lJoaj1km2NhA3cwqJjqkx4VAJhLlEuG5wDlTSRXNpzqfamdZcH-XMG2rM-nh6yFqbSzyaeO99ZnGMDp5mZvzGuR0VmV6IXPXqelP4uT9cPQD60h1v2DaOKlmd-0ghGfdHa0hzR5S8C55oZ5hF1_bhgx6tA8VzC1jp41mDbKmKAOKvcFG2T9JQRBml2izRVVaCsVN0_ZCR7NhQYrkreqgVN_ZLlgzI6YSA2EN1FWmc9GvNFAbQ",
           "e": "AQAB",
           "use": "sig",
           "kid": "ut-Fle8JH9IdPqo7QDDakblWR1DdvMIijJT9A-lVntk",
           "qi": "uoncSFVC9_vS652rNSZQO8I7KCk0b2bpt38Sb1iQ8Vha5lYkrTp-AsZLoduj7TscCCqlftm9R-FkfERjEYZLdPKQIaGcCQ-L0RzIG_K3w48Tk2T_EEiMqds4UeBpQxccMjUvX-t_b7pwMjFL1RIEBSWAxg5YShT8C83hv0llh9Y",
           "dp": "BLMxWSfyPqhl0Bf7AA_lOaMDktdMzBVo1uiYmn-jnWJOypn9DKjx03Gap9u9Fpeou7dipe51ImAPQ2dtyqvivv4F1wNDD6AzCWuxLrhgvSHLtueMrxk5FDoH-wiCDRxD2-gK9eNKW3C0wzdDq7xW9b-8c3ZtsUhG2xzBF0bC8UU",
           "alg": "RS256",
           "dq": "R_ji4BhWOlcq9NaGg1I5zEVQ6kw1OPtFbOIW6C0Td1qtGomySSKibslvgBNFeH9auqdaUOZjBVWowx1pE-h8pM3AHJsw4sz6T9K0qSrAM_r4xdxXtThfovRWNkLCV0ZzE7sV2DixA06avDUNHbuHpgyAEZsP3kO_K-qx6jQYAc0",
           "n": "jAQFAKQ9omNtb_I2iSryCulJnkB56qGf35fA1RrDBLup7ysJCez9dnu-HTZ62SKoe-9Pxu-4WzjjBNQacotUXYTIi7GFWM5Pyb4ha-bBJprbiwhyrYGIVzZw4LIcleexWPcIOI0cTKmpM6qKb9_6CTFa-A6uX_16n-n3fQjWGPKrJBY7mcIalJ4YTmLhavs6yt6efSD67SaJ2FabzjouRa_yeDmsGPq2LA-4FymDvuGCHeeMtPO9ClnA2eWC15L7n3-Pagm5pso5GchORl2Rwr_bhCmNCKsC_Qh6TqTHJyymuJwZIuSOv88cf-5UsSidRSJ9r0dBl0S0KgndCagD6Q"
        }
     ]
  }

Public Keys

Every private key will have an associated public key that can be freely distributed to other parties. The main purpose of these public keys is to verify signatures attached to payloads (such as JWTs) that were signed using the private key.

In most cases, the only public keys you need to concern yourselves with are the public keys belonging to the identity provider you're using. These are needed to verify the signatures of the tokens that are signed and issued by the identity provider.

Conversely, your client application might use client assertions to authenticate itself with an identity provider. As part of the automated provisioning process, the platform will pre-register corresponding public keys for your client at the identity provider. The identity provider will in turn use these public keys to verify the signature of your client assertions as proof of your client's identity.

Public JWK (click to expand)
  {
      "kty": "RSA",
      "e": "AQAB",
      "use": "sig",
      "kid": "ut-Fle8JH9IdPqo7QDDakblWR1DdvMIijJT9A-lVntk",
      "alg": "RS256",
      "n": "jAQFAKQ9omNtb_I2iSryCulJnkB56qGf35fA1RrDBLup7ysJCez9dnu-HTZ62SKoe-9Pxu-4WzjjBNQacotUXYTIi7GFWM5Pyb4ha-bBJprbiwhyrYGIVzZw4LIcleexWPcIOI0cTKmpM6qKb9_6CTFa-A6uX_16n-n3fQjWGPKrJBY7mcIalJ4YTmLhavs6yt6efSD67SaJ2FabzjouRa_yeDmsGPq2LA-4FymDvuGCHeeMtPO9ClnA2eWC15L7n3-Pagm5pso5GchORl2Rwr_bhCmNCKsC_Qh6TqTHJyymuJwZIuSOv88cf-5UsSidRSJ9r0dBl0S0KgndCagD6Q"
  }
Public JWKS / JWK Set (click to expand)
  {
     "keys": [
        {
           "kty": "RSA",
           "e": "AQAB",
           "use": "sig",
           "kid": "ut-Fle8JH9IdPqo7QDDakblWR1DdvMIijJT9A-lVntk",
           "alg": "RS256",
           "n": "jAQFAKQ9omNtb_I2iSryCulJnkB56qGf35fA1RrDBLup7ysJCez9dnu-HTZ62SKoe-9Pxu-4WzjjBNQacotUXYTIi7GFWM5Pyb4ha-bBJprbiwhyrYGIVzZw4LIcleexWPcIOI0cTKmpM6qKb9_6CTFa-A6uX_16n-n3fQjWGPKrJBY7mcIalJ4YTmLhavs6yt6efSD67SaJ2FabzjouRa_yeDmsGPq2LA-4FymDvuGCHeeMtPO9ClnA2eWC15L7n3-Pagm5pso5GchORl2Rwr_bhCmNCKsC_Qh6TqTHJyymuJwZIuSOv88cf-5UsSidRSJ9r0dBl0S0KgndCagD6Q"
        }
     ]
  }

Login proxy

NAIS offers an opt-in login proxy (also known as Wonderwall) that simplifies the process of authenticating end-users in your application. The proxy exposes endpoints under your application's ingress to help you authenticate employees or citizens.

Availability

Login proxy is only available in the Google Cloud Platform environments.

The proxy sits in front of your application and intercepts all incoming requests. Unauthenticated requests are proxied as-is.

graph LR
  style Proxy stroke:#0f0,stroke-dasharray: 5
  style Application stroke:#f00
    
  U((User)) -- "request" ---> Proxy["Login proxy"]
  Proxy -. "proxy request\n as-is" -..-> Application

To log in an end-user, redirect them to the login endpoint.

graph LR
  IDP[Identity Provider]
  style Proxy stroke:#0f0,stroke-dasharray: 5
  style IDP stroke:#f00

  U((User)) -- "/oauth2/login" --> Proxy["Login proxy"]

  subgraph OIDC["OpenID Connect Authorization Code Flow"]
    IDP -- "redirect callback" ---> Proxy
    Proxy -- "redirect to log in" ---> IDP
  end

After successful login, the proxy creates and stores a session for the end-user. Requests from the user agent will now contain their access token as a Bearer token in the Authorization header.

graph LR
  style Proxy stroke:#0f0,stroke-dasharray: 5
  style Application stroke:#f00

  subgraph Session["Authenticated Session"]
    direction LR
    U((User)) -- "request" ---> Proxy["Login proxy"]
    Proxy -. "proxy request\n with token" -..-> Application
  end

Sessions

When an end-user authenticates themselves, they receive a session. Sessions are stored server-side and are managed by the login proxy; we only store a session identifier at the end-user's user agent.

A session has three possible states:

  • active - the session is valid
  • inactive - the session has reached the inactivity timeout and is considered invalid
  • expired - the session has reached its maximum lifetime and is considered invalid

Requests with an invalid session are considered unauthenticated; they must get a new session by performing a new login.

See the session management reference for more details.

Autologin

The autologin option configures the login proxy to enforce authentication for all requests, except for the paths that are explicitly excluded.

Autologin vs. token validation

Always validate tokens in requests for any endpoint that requires authentication. Autologin does not perform nor is it a replacement for token validation.

Validation is especially important for requests that access sensitive data or otherwise performs operations that modify state.

If the user is unauthenticated, all requests will be short-circuited (i.e. return early and not proxied to your application). The response depends on whether the request is a top-level navigation request or not.

What is a top-level navigation request?

A top-level navigation request is a GET request that fulfills at least one of the following properties:

  1. Has the Fetch metadata request headers Sec-Fetch-Dest=document and Sec-Fetch-Mode=navigate, or
  2. Has an Accept header that includes text/html

All major modern browsers sends at least one of these for navigational requests, with Internet Explorer 8 being the only known exception. Hopefully you're not in a position that requires supporting that browser.

Ensure that your frontend code handles HTTP 401 responses and appropriately notifies the user or redirects them to the login endpoint.

Further Reading