OAuth2 and OpenID Connect are both pervasive technologies in modern identity systems. While verification of JSON web tokens issued by these systems is documented in the policy reference, the policy examples below aim to cover some other common use cases.
Metadata discovery
Rather than storing endpoints and other metadata as part of policy data, the authorization server metadata endpoint may be queried for this data.
package oidc
issuers = {"https://issuer1.example.com", "https://issuer2.example.com"}
metadata_discovery(issuer) = http.send({
"url": concat("", [issuers[issuer], "/.well-known/openid-configuration"]),
"method": "GET",
"force_cache": true,
"force_cache_duration_seconds": 86400 # Cache response for 24 hours
}).body
claims := jwt.decode(input.token)[1]
metadata = metadata_discovery(claims.iss)
jwks_endpoint := metadata.jwks_uri
token_endpoint := metadata.token_endpointToken verification using JWKS endpoint
Below example uses the keys published at the JWKS endpoint of the authorization server for token verification.
package oidc
jwks_request(url) = http.send({
"url": url,
"method": "GET",
"force_cache": true,
"force_cache_duration_seconds": 3600 # Cache response for an hour
})
jwks = jwks_request("https://authorization-server.example.com/jwks").raw_body
verified = io.jwt.verify_rs256(input.token, jwks)Key rotation
Use the keys published at the JWKS endpoint of the authorization server for token verification, with key rotation taken into account.
package oidc
jwks_request(url) = http.send({
"url": url,
"method": "GET",
"force_cache": true,
"force_cache_duration_seconds": 3600
})
jwt_unverified := io.jwt.decode(input.token)
jwt_header := jwt_unverified[0]
# Use the key ID (kid) from the token as a cache key - if a new kid is encountered
# we obtain a fresh JWKS object as the keys have likely been rotated.
jwks_url := concat("?", [
"https://authorization-server.example.com/jwks",
urlquery.encode_object({"kid": jwt_header.kid}),
])
jwks = jwks_request(jwks_url).raw_body
jwt_verified = jwt_unverified {
io.jwt.verify_rs256(input.token, jwks)
}
claims_verified := jwt_verified[1]Token retrieval
Programmatically obtain an OAuth2 access token following the client credentials or resource owner password credential flow.
package oauth2
token = t {
response := http.send({
"url": "https://authorization-server.example.com/token",
"method": "POST",
"headers": {
"Content-Type": "application/x-www-form-urlencoded",
"Authorization": concat(" ", [
"Basic",
base64.encode(sprintf("%v:%v", [client_id, client_secret]))
]),
},
# To use the resource owner password credentials flow, change grant_type
# to "password" and add username and password parameters to the body
"raw_body": "grant_type=client_credentials",
"force_cache": true,
"force_cache_duration_seconds": 3595, # Given an `expires_in` value of 3600
})
response.status_code == 200
t := response.body.access_token
}Feedback
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