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jwt-auth-demo/docs/output/rs-converter-java.txt
Ankur Mhatre 4dc45d5e00 Add OAuth2 resource server project: JWT validation, JWKS and key rotation
Companion code for the follow-up article. The repository now holds two Maven
projects sharing one docs/ tree:

  jwt-authentication/       the hand-written filter application (unchanged, moved)
  oauth2-resource-server/   a resource server, a Keycloak compose, and a stub
                            issuer whose JWK Set can be mutated on command

The stub exists because Keycloak will not rotate a signing key at a chosen
second, report how many times its JWKS endpoint was fetched, or drop a key from
the published set on request - and the caching and rotation measurements need
all three. The Keycloak run confirms the same code path against a real issuer.

Findings captured under docs/output/, all from real runs:

  * The default validator stack does not check aud. A token minted for another
    service in the same realm is accepted.
  * Spring Security builds its JWKSource with refreshAheadCache(false) and
    rateLimited(false), overriding two of Nimbus's protective defaults, and
    enables Nimbus caching only when NO Spring cache was supplied - so
    supplying one removes the five-minute expiry.
  * A key retired from the JWK Set stops being accepted at t+300s with the
    default cache, and never with a Spring cache that has no TTL.
  * 25 tokens carrying an unknown kid produce 25 JWKS fetches at the issuer,
    through permitAll() endpoints included.
  * A hyphenated client id in an authorities-claim-expression parses as
    subtraction; the SpelEvaluationException is swallowed and logged at TRACE.
  * A clientScopes key in a Keycloak realm import replaces the built-in scopes
    rather than adding to them.

New docs chapters 12-18. README covers both projects. Existing docs and scripts
updated for the new paths; no docs/output/ file from the first article moved, so
links in the published article still resolve.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013f7f2XZXrQ6gW3RtZE187t
2026-08-23 11:00:56 +00:00

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--------------------------------------------------------------------------
resource server profiles: stub,roles
--------------------------------------------------------------------------
--------------------------------------------------------------------------
1. alice - realm role USER, client role reports-reader
--------------------------------------------------------------------------
header: {"kid": "stub-key-1", "typ": "JWT", "alg": "RS256"}
iss "http://localhost:9000"
aud "reports-api"
scope "profile:read reports:read"
preferred_username "alice"
realm_access {"roles": ["USER"]}
resource_access {"reports-api": {"roles": ["reports-reader"]}}
$ GET /api/me (which authorities did the converter produce?)
HTTP 200
{
"name": "alice",
"authorities": [
"FACTOR_BEARER",
"ROLE_USER",
"ROLE_reports-reader",
"SCOPE_profile:read",
"SCOPE_reports:read"
],
"iss": "http://localhost:9000",
"aud": [
"reports-api"
],
"typ": "JWT",
"kid": "stub-key-1",
"exp": "2026-08-23T10:33:11Z"
}
$ GET /api/reports (needs ROLE_reports-reader, from resource_access)
HTTP 200
{
"reports": 3
}
$ GET /api/admin/stats (needs ROLE_ADMIN, from realm_access)
HTTP 403
WWW-Authenticate: Bearer error="insufficient_scope", error_description="The request requires higher privileges than provided by the access token.", error_uri="https://tools.ietf.org/html/rfc6750#section-3.1"
--------------------------------------------------------------------------
2. root - realm roles USER and ADMIN
--------------------------------------------------------------------------
$ GET /api/me
HTTP 200
{
"name": "root",
"authorities": [
"FACTOR_BEARER",
"ROLE_ADMIN",
"ROLE_USER",
"ROLE_reports-reader",
"SCOPE_profile:read",
"SCOPE_reports:read"
],
"iss": "http://localhost:9000",
"aud": [
"reports-api"
],
"typ": "JWT",
"kid": "stub-key-1",
"exp": "2026-08-23T10:33:11Z"
}
$ GET /api/admin/stats
HTTP 200
{
"secret": "only ROLE_ADMIN sees this"
}