Ankur Mhatre
e9381dc5be
Three modules on Spring Boot 4.1.1 with Spring Authorization Server 7.1.1: the provider
itself, a relying party, and an API that trusts its tokens. Client registration, PKCE,
a custom consent page and token customisation, with profiles that make each failure
reproducible.
Every claim is backed by captured output in docs/output/as-*.txt, regenerated by
authorization-server/scripts/run-all.sh. Notable findings, verified against the jars:
- OAuth2AuthorizationServerConfiguration.applyDefaultSecurity(HttpSecurity) was deleted
in 7.0, and both configuration classes moved into spring-security-config
- ClientSettings.requireProofKey flipped from false to true, on the authorization server
(1.5.8 -> 7.1.1) and on the OAuth2 client (6.5.1 -> 7.1.1)
- requireProofKey(false) does not make PKCE optional for a public client; the code
verifier is that client's only authentication at the token endpoint
- MediaTypeRequestMatcher(TEXT_HTML) matches Accept: */*, so the token endpoint answers
API callers with 302 -> /login unless setIgnoredMediaTypes(ALL) is called
Also renames the repository to spring-auth-demo and cross-links the new chapter set from
the existing documentation.
141 lines
8.1 KiB
Plaintext
141 lines
8.1 KiB
Plaintext
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------------------------------------------------------------------
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== PKCE parameters (RFC 7636)
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------------------------------------------------------------------
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code_verifier s3e6dmr3wSf4_lvze8F93m7moAckkHVcu6hKAerx3Ug77jqz38_iNhnOtio2dNj6 (64 chars)
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code_challenge fIGXtoxshuoWNmv8gk1b7wWtLzxOzB0fSenfe02UwAs
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code_challenge_method S256
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The verifier never leaves the client until the token request. The challenge is
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all the authorization request carries, and it is a one-way hash of the verifier.
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------------------------------------------------------------------
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== 1. Log in to the authorization server (browser session)
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------------------------------------------------------------------
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$ curl -c jar -d username=alice -d password=password -d _csrf=<token> http://localhost:9000/login
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HTTP/1.1 302
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Location: http://localhost:9000/
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------------------------------------------------------------------
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== 2. GET /oauth2/authorize (client=demo-spa)
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------------------------------------------------------------------
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$ curl -b jar 'http://localhost:9000/oauth2/authorize?response_type=code&client_id=demo-spa&redirect_uri=http%3A%2F%2F127.0.0.1%3A8080%2Fauthorized&scope=openid%20orders.read&state=xyz123&code_challenge=fIGXtoxshuoWNmv8gk1b7wWtLzxOzB0fSenfe02UwAs&code_challenge_method=S256'
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-> 302 http://localhost:9000/oauth2/consent?scope=openid%20orders.read&client_id=demo-spa&state=zjgza5hwc4CbJeJepOgTFZXTDk1IBgjWjsGo_mupymU%3D
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------------------------------------------------------------------
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== 3. The consent page
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------------------------------------------------------------------
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The authorization endpoint redirected to OUR page, at the path given to
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.consentPage("/oauth2/consent"). Note the query string it hands over:
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http://localhost:9000/oauth2/consent?scope=openid%20orders.read
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client_id=demo-spa
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state=zjgza5hwc4CbJeJepOgTFZXTDk1IBgjWjsGo_mupymU%3D
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Scopes rendered as checkboxes (openid deliberately not among them):
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orders.read
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The hidden state the form must echo back: zjgza5hwc4CbJeJepOgTFZXTDk1IBgjWjsGo_mupymU=
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(this is NOT the client's state=xyz123 - it is the server's own correlation
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handle for the pending authorization request, and sending the client's value
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instead is what produces the consent redirect loop)
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------------------------------------------------------------------
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== 4. POST the approval to /oauth2/authorize
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------------------------------------------------------------------
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$ curl -b jar -X POST -d client_id=demo-spa -d state=zjgza5hwc4CbJeJepOgTFZXTDk1IBgjWjsGo_mupymU= -d _csrf=f7zUD7ezBE6G0H5DQuPikT9CkEEKR9JuA2Y8njWwhSkoewGDG4ziN46BZXerthpycc7Wp1x6vSBrJetDOwMLr1SI4EpOGDG1 -d scope=orders.read http://localhost:9000/oauth2/authorize
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-> 302 http://127.0.0.1:8080/authorized?code=whzdCa9Z_53d6sCkZYkNNswxQLQ46kDsMy9ynR0rOvy6KqP741fpHOAC5nF4PsN6O0Sqvi3R9kksVer6L6V3Zk9Ii_LcHOYdHqWGEiE9O8jDDRJjqr-LiTnpEDI12St1&state=xyz123
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------------------------------------------------------------------
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== 5. The authorization code
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------------------------------------------------------------------
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code = whzdCa9Z_53d6sCkZYkNNswxQLQ46kDsMy9ynR0rOvy6KqP741fpHOAC5nF4PsN6O0Sqvi3R9kksVer6L6V3Zk9Ii_LcHOYdHqWGEiE9O8jDDRJjqr-LiTnpEDI12St1
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state = xyz123 (the client's own value, returned untouched - compare it)
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------------------------------------------------------------------
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== 6a. Exchange the code WITHOUT the verifier
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------------------------------------------------------------------
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This is the request an attacker who stole the code can make.
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HTTP 401
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(empty response body)
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>>> Rejected. invalid_grant is deliberately vague: the server will not tell
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>>> a caller whether the code was wrong, expired, already used, or missing a
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>>> verifier, because each of those is information an attacker can use.
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Note: this consumed the code. Authorization codes are single-use, so the
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successful exchange below needs a fresh one.
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------------------------------------------------------------------
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== 6b. A fresh code, exchanged properly
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------------------------------------------------------------------
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fresh code = B3GUYBE-2tE9C3eSx8_m8ejjXhPwFYEHuTrMwvmNpj-xZuDsPhutSgDt3pY88aE4bSmclgB8mDWFb_SiCODkeheeyCkogZkPwSLFFY4MqbZ1WlUipMynXR1jn9L0UIav
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$ curl -d grant_type=authorization_code -d code=... -d code_verifier=... http://localhost:9000/oauth2/token
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HTTP 200
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{
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"access_token": "eyJraWQiOiIyYjNjZGFhMy1kMDE1LTQ3NTItOWZiYS0xNmM3YjI0NTJiNTciLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJhbGljZSIsImF1ZCI6Im9yZGVycy1hcGkiLCJuYmYiOjE3ODc1Mzg3NDYsInNjb3BlIjpbIm9wZW5pZCIsIm9yZGVycy5yZWFkIl0sInJvbGVzIjpbIkFETUlOIiwiVVNFUiJdLCJpc3MiOiJodHRwOi8vbG9jYWxob3N0OjkwMDAiLCJleHAiOjE3ODc1MzkwNDYsImlhdCI6MTc4NzUzODc0NiwianRpIjoiZmI3ZTUyOTEtMTc2OC00NjI2LWJhODUtNWQ3NWI2OGZmNjcyIiwidGVuYW50IjoiYWNtZSJ9.e048ANvC61A6JPe7rE5k_aQDFcQTTCWNRg11j6Nj3MoUsqPvRIPFtYWvK0_l20HnUWZn0X84hy-ifgi4f_nBYDXDXFI-Ya2bRjRnnhtincjZsLNB8RUUDK5tqAPMSdfcceM48cTLLDrvwrxIp0ASG697aBuRVmndcUWyMVfZPzSidR3h0ydeWUVaY7NmL8d6pOzgLLNlDTIjyipURUboda7Mcw7KTHxodM_saz1xwQTzozRtcybmreUw44O6b07wjATcIzAwAJzASaiX2ElUyYs9lWAtxQ-JSiGX4htmfLJiONVnuEZNSy3uvLQnTfnl4G4OY2mjK1zJzIT-wBfX6w",
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"scope": "openid orders.read",
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"id_token": "eyJraWQiOiIyYjNjZGFhMy1kMDE1LTQ3NTItOWZiYS0xNmM3YjI0NTJiNTciLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJhbGljZSIsImF1ZCI6ImRlbW8tc3BhIiwiYXpwIjoiZGVtby1zcGEiLCJhdXRoX3RpbWUiOjE3ODc1Mzg3NDYsImlzcyI6Imh0dHA6Ly9sb2NhbGhvc3Q6OTAwMCIsInByZWZlcnJlZF91c2VybmFtZSI6ImFsaWNlIiwiZXhwIjoxNzg3NTQwNTQ2LCJpYXQiOjE3ODc1Mzg3NDYsImp0aSI6IjBjY2IzZjI4LTk1MWYtNGU5ZS1iNzkzLTNjNWExNjdmNDg1MSIsInNpZCI6InQ1dUpXUDM2V1dYWTNXX2hkaURueTR1OGlEZlVyZHlLd1EyRE9XWUdoSzgifQ.B6kGKui5mOyakllBv7xmmlVcsy6BYUN-JNALZLKMPz-O0WZO6WigSYfHKXdHtYVGsNdxVpFgeyWYPyi6JOTX9ALaDeJcEAiUwZFEN4PJa-lSzZvdT6m5atD1OCQqXOd7c_4bqD596I94Gu22arBij6UYaNBagLdBmtbAhJYMhBT5Q7Ygzo5m0w7Ru-oxU_cK06R4ZggNGo9B0NWJfqXroTOdFzfJmptl3CN9Ddh14pj5pz4w0hAMkxSMsJ-GAgm85ldD9aGVzFfjZ4-lzI7gveUVn_IzWZQbCY3_SYUuoGQFe60I0L6cDyot88qfuXn3m1udEaQVvrJlE7SBxMIFmQ",
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"token_type": "Bearer",
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"expires_in": 299
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}
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------------------------------------------------------------------
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== 7. The access token
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------------------------------------------------------------------
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{
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"alg": "RS256",
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"kid": "2b3cdaa3-d015-4752-9fba-16c7b2452b57"
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}
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{
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"aud": "orders-api",
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"exp": 1787539046,
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"iat": 1787538746,
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"iss": "http://localhost:9000",
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"jti": "fb7e5291-1768-4626-ba85-5d75b68ff672",
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"nbf": 1787538746,
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"roles": [
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"ADMIN",
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"USER"
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],
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"scope": [
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"openid",
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"orders.read"
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],
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"sub": "alice",
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"tenant": "acme"
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}
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------------------------------------------------------------------
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== 8. The id_token - a different token, for a different audience
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------------------------------------------------------------------
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{
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"aud": "demo-spa",
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"auth_time": 1787538746,
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"azp": "demo-spa",
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"exp": 1787540546,
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"iat": 1787538746,
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"iss": "http://localhost:9000",
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"jti": "0ccb3f28-951f-4e9e-b793-3c5a167f4851",
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"preferred_username": "alice",
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"sid": "t5uJWP36WWXY3W_hdiDny4u8iDfUrdyKwQ2DOWYGhK8",
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"sub": "alice"
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}
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aud is the CLIENT here, not the API. Sending this to a resource server is the
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classic mix-up: it verifies (same issuer, same key) and then fails the audience
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check, or worse, passes it if nobody checks audience.
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------------------------------------------------------------------
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== 9. Calling the resource server
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------------------------------------------------------------------
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GET /api/orders -> 200
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{"orders":[{"total":"42.00","id":1}],"subject":"alice","clientId":null,"scopes":["openid","orders.read"],"roles":["ADMIN","USER"],"tenant":"acme","audience":["orders-api"]}
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GET /api/admin -> 200
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{"authorities":["SCOPE_openid","ROLE_USER","SCOPE_orders.read","ROLE_ADMIN","FactorGrantedAuthority [authority=FACTOR_BEARER, issuedAt=2026-08-24T02:32:26.714311634Z]"],"message":"admin only"}
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------------------------------------------------------------------
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== 10. Sending the id_token instead
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------------------------------------------------------------------
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HTTP/1.1 401
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WWW-Authenticate: Bearer error="invalid_token", error_description="An error occurred while attempting to decode the Jwt: the required audience orders-api is missing", error_uri="https://tools.ietf.org/html/rfc6750#section-3.1", resource_metadata="http://localhost:8090/.well-known/oauth-protected-resource"
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