OpenID Connect | Login.gov

Authorization

The authorization endpoint handles authentication and authorization of a user. To present the Login.gov authorization page to a user, direct them to the /openid_connect/authorize. View an example for private_key_jwt or PKCE in the side panel.

Request Parameters

JWT
PKCE

acr_values

The Authentication Context Class Reference requests can be used to specify the type of service level or the AAL (Authentication Assurance Level) for the user. These and the scope determine which user attributes will be available in the user info response.

Multiple values can be joined with a space (before being URI-escaped in the final URL).

A type of service level must be specified.

urn:acr.login.gov:auth-only
Requires basic identity assurance: email address, password, and at least one MFA method. No identity verification.

Meets either NIST 800-63-3 AAL1 or AAL2 standard (depending on agency integration configuration)
urn:acr.login.gov:verified
Requires that the user has gone through basic identity verification without facial matching.

Does not meet NIST 800-63-3 IAL2 standard.
urn:acr.login.gov:verified-facial-match-required
Requires identity verification with facial match for all users. Even if a user has been previously verified without facial matching, they will be required to go through verification with facial match.

Meets NIST 800-63-3 IAL2 standard.
urn:acr.login.gov:verified-facial-match-preferred
Requires identity verification. Users with no previous identity verification will be required to go through a facial match. Users with previous identity verification will use that data, even if it was done without facial match.

Authentications for users who verify with facial matching will meet NIST 800-63-3 IAL2 standard. Authentication for users who do not do facial matching will not meet NIST 800-63-3 IAL2 standard.

We default to requiring a user to be authenticated with a second factor:

urn:gov:gsa:ac:classes:sp:PasswordProtectedTransport:duo
This specifies that a user has been authenticated with a second factor. This value will be returned in the user attributes by default. We do not allow strict AAL1, because it implies that a user did not authenticate with a second factor. This setting requires users to reauthenticate with a separate second factor (i.e. not a remembered device) once every 30 days at a minimum.

Stricter behavior can be specified by adding one of:

http://idmanagement.gov/ns/assurance/aal/2
This is the same as the default behavior except users must authenticate with a separate second factor (i.e. not a remembered device).
http://idmanagement.gov/ns/assurance/aal/2?phishing_resistant=true
This specifies that a user has been authenticated with a crytographically secure method, such as WebAuthn or using a PIV/CAC. Users must always authenticate with a second factor.
http://idmanagement.gov/ns/assurance/aal/2?hspd12=true
This specifies that a user has been authenticated with an HSPD12 credential (requires PIV/CAC). Users must always authenticate with a second factor.

These are not recommended, and only for legacy compatibility.

http://idmanagement.gov/ns/assurance/ial/1
Requires basic identity assurance, does not require identity verification. Equivalent to urn:acr.login.gov:auth-only.
http://idmanagement.gov/ns/assurance/ial/2
Requires that the user has gone through basic identity verification. Equivalent to urn:acr.login.gov:verified.

Does not meet NIST 800-63-3 IAL2 standard.
http://idmanagement.gov/ns/assurance/loa/1
Equivalent to urn:acr.login.gov:auth-only.
http://idmanagement.gov/ns/assurance/loa/3
Equivalent to urn:acr.login.gov:verified.

client_id

Also known as the issuer, this is the unique identifier for the client. This will be registered with the Login.gov IdP in advance.

code_challenge

required for PKCE

The RFC 4648 URL-safe Base64 encoding of the SHA256 binary digest of a random value generated by the client. The original random value is referred to as the code_verifier and is later used with the token endpoint. Generating these values in Ruby might look like this, for example:

Correct Example

code_verifier = SecureRandom.hex
=> "5787d673fb784c90f0e309883241803d"
code_challenge = Digest::SHA256.digest(code_verifier)
=> "\xD4\x15)\xC7-\xFBJ\x82\x0F\x98\xAC=\xEB\x06\xDD\xE8\xC0\xDC\xBD\xAC\x8Ebm\xE9\xB5?\xB3m\xEE\x8B\xFF3" # binary digest
url_safe_code_challenge = Base64.urlsafe_encode64(code_challenge)
# RFC 4648 URL-safe Base64 encoding replaces "+" with "-" and "/" with "_"
=> "1BUpxy37SoIPmKw96wbd6MDcvayOYm3ptT-zbe6L_zM="

Incorrect Example

=> "1BUpxy37SoIPmKw96wbd6MDcvayOYm3ptT-zbe6L_zM"
Base64.encode64(code_challenge) # wrong and URL-unsafe encoding
=> "1BUpxy37SoIPmKw96wbd6MDcvayOYm3ptT+zbe6L/zM=" # wrong and URL-unsafe encoding

code_challenge_method

required for PKCE

This must be S256, the only PKCE code challenge method supported.

prompt

This must be select_account

response_type

This must be code

redirect_uri

The URI Login.gov will redirect to after a successful authorization.

scope

A space-separated string of the scopes being requested. (Keep in mind the blank space “ “ should be encoded with “+”.) The authorization page will display the list of attributes being requested from the user. Applications should aim to request the fewest user attributes and smallest scope needed.

Possible values are:

openid
address
email
all_emails
phone
profile:birthdate
profile:name
profile:verified_at
profile
social_security_number
x509
x509:issuer
x509:presented
x509:subject

state

A unique value, at least 22 characters in length, used for maintaining state between the request and the callback. This value will be returned to the client on a successful authorization.

nonce

A unique value, at least 22 characters in length, used to verify the integrity of the id_token and mitigate replay attacks. This value should include per-session state and be unguessable by attackers. This value will be present in the id_token of the token endpoint response, where clients will verify that the nonce claim value is equal to the value of the nonce parameter sent in the authentication request. Read more about nonce implementation in the spec.

locale

optional

If you know that a user would prefer one of our alternative language translations (currently Spanish or French), you can include the locale parameter to specify the language Login.gov should use (either es for Spanish or fr for French).

      PKCE Requesthttps://idp.int.identitysandbox.gov/openid_connect/authorize?
  acr_values=urn:acr.login.gov:auth-only&
  client_id=${CLIENT_ID}&
  code_challenge=${CODE_CHALLENGE}&
  code_challenge_method=S256&
  nonce=${NONCE}&
  prompt=select_account&
  redirect_uri=${REDIRECT_URI}&
  response_type=code&
  scope=openid+email&
  state=abcdefghijklmnopabcdefghijklmnop

  

Authorization response

After an authorization, Login.gov will redirect to the provided redirect_uri.

In a successful authorization, the URI will contain the two parameters code and state:

code — A unique authorization code the client can pass to the token endpoint.
state — The state value originally provided by the client. Validate that the value is the same.

In an unsuccessful authorization, the URI will contain the parameters error and state, and optionally error_description:

error — The error type, either:
- access_denied — The user has either cancelled or declined to authorize the client.
- invalid_request — The authorization request was invalid. The error_description parameter will provide a description.
error_description — A description of the error.
state — The state value originally provided by the client.

Next step: Token

      
      https://agency.gov/response?
  code=12345&
  state=abcdefghijklmnopabcdefghijklmnop

      https://agency.gov/response?
  error=access_denied&
  state=abcdefghijklmnopabcdefghijklmnop

Next step: Token

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