Ankur Mhatre
38c0a5f358
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 C9PyP-Bxq-_AwoSFt1hAHGO6klWLddojkvIaIR1-vTzzTkjtc6o9c71G-yVYQwKf (64 chars)
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code_challenge FlJK8n-vjKPJ9-ZQPGrBm4JqIvhUotk67SUZRkXXJ3o
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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=FlJK8n-vjKPJ9-ZQPGrBm4JqIvhUotk67SUZRkXXJ3o&code_challenge_method=S256'
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-> 302 http://localhost:9000/oauth2/consent?scope=openid%20orders.read&client_id=demo-spa&state=s4VpkAnwpXo3Q9sekOo3MJVSaZgwc_AJnZMNIqcHvpE%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=s4VpkAnwpXo3Q9sekOo3MJVSaZgwc_AJnZMNIqcHvpE%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: s4VpkAnwpXo3Q9sekOo3MJVSaZgwc_AJnZMNIqcHvpE=
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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=s4VpkAnwpXo3Q9sekOo3MJVSaZgwc_AJnZMNIqcHvpE= -d _csrf=pQeZvH9HfbMeKSIJ5Tgv-82ImtETjf8f3pu1C0Ukgwnkyy9_lDX9iE12HNUzGRA_3RUbmqy9t-glv50y7qKGOiRCujHU_Eod -d scope=orders.read http://localhost:9000/oauth2/authorize
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-> 302 http://127.0.0.1:8080/authorized?code=f5H5d-BObbl65Mzu2LE_Lg6QmVgG31gd_1__sJ28KSIjHqbr9yp0o4sq-Q9NqADqXc2Bemfdiod46rduBfDmvygYYvvhadjjn5ZQcYHGNfipjZoTQ4oxjDFQJYldbS4H&state=xyz123
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------------------------------------------------------------------
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== 5. The authorization code
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------------------------------------------------------------------
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code = f5H5d-BObbl65Mzu2LE_Lg6QmVgG31gd_1__sJ28KSIjHqbr9yp0o4sq-Q9NqADqXc2Bemfdiod46rduBfDmvygYYvvhadjjn5ZQcYHGNfipjZoTQ4oxjDFQJYldbS4H
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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 = 5eNIeklP92R9ihz7RAuR_3cwTdlRKhqMXLSVVyNGei_jHwwsTiFIpHe_4bDLIdO0GbrLkkQ4NWAOD5XE1u1gsNB7xtfNEf9t6zTEyeu0EQ4tEtklkKpGtnfGMsKU1XZR
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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": "eyJraWQiOiIyNjJiZDU1MC0zNjU3LTQ2YzQtYmFmYy1jY2U0YzZmNGUwY2IiLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJhbGljZSIsImF1ZCI6Im9yZGVycy1hcGkiLCJuYmYiOjE3ODc1Mzg3MTQsInNjb3BlIjpbIm9wZW5pZCIsIm9yZGVycy5yZWFkIl0sInJvbGVzIjpbIkFETUlOIiwiVVNFUiJdLCJpc3MiOiJodHRwOi8vbG9jYWxob3N0OjkwMDAiLCJleHAiOjE3ODc1MzkwMTQsImlhdCI6MTc4NzUzODcxNCwianRpIjoiMWQ5NGFjYmMtZTI0NS00MGZiLWE3NWQtMDVhYjNiYzI5NGI2IiwidGVuYW50IjoiYWNtZSJ9.f0zh8PyK_6luy-npcr4zZj-ZHeqbrCtGI-b3SBlyE36RAu1PDXv6WP7ZQjV-9DWn7fSmD7mClOVSOdCZDXx9Y9jsCAvGwyV3DHeFutJHcM5pqrdX7n31TmPgFZgaXko8bK34qs62ic8pwNKKEL2R0jAYeVLqlGtPYVo1a5hMvXNxYARC519wKzfIJMMYtEiecOlk5n9m41lXk3WT4EvqN72zeQBgOnJBqd75vwTyr27UwLlXoGfeuu1cUBXzEg0COw4Eirv-P7zhvTpGSc8oich_At_TYip9GyOLnfNK60p_QJEPMnhCvye6ooXi6tiQ2kbHxdodTlTWDYId0wA6nQ",
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"scope": "openid orders.read",
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"id_token": "eyJraWQiOiIyNjJiZDU1MC0zNjU3LTQ2YzQtYmFmYy1jY2U0YzZmNGUwY2IiLCJhbGciOiJSUzI1NiJ9.eyJzdWIiOiJhbGljZSIsImF1ZCI6ImRlbW8tc3BhIiwiYXpwIjoiZGVtby1zcGEiLCJhdXRoX3RpbWUiOjE3ODc1Mzg3MTMsImlzcyI6Imh0dHA6Ly9sb2NhbGhvc3Q6OTAwMCIsInByZWZlcnJlZF91c2VybmFtZSI6ImFsaWNlIiwiZXhwIjoxNzg3NTQwNTE0LCJpYXQiOjE3ODc1Mzg3MTQsImp0aSI6ImRjM2JiZTMyLTBlMmEtNDUwYi1hNjVjLTU0YzQ0M2E4NTcwZCIsInNpZCI6ImNIb29WN2Nqa0ctV0t4ZC1NWTJyNDM0SXRJYXhwcXJZR1VPbENCVjY3OHcifQ.fCsxjhoqx7WQLXoN5eV6e1zrPB1MgHPZVbmW5HixQPcmvqqu2Zk--4sPsngPJBrLXKTcKEJeUM4jGvugkfQMnAIYu4stafM5_lJXwgA-Rvd7DgDzmzpXtfWpBDPsuuoiHyG00Hp9evbru0qHbfKFA4d4KarJTw9F1OHx5b_3H2Z3CGLh33ZZZG6zC2ki4wOg__GKmfw00p6OeRRfNIL_1zr4ZFv6xF0VynZdSOA1_0XtRBv1J-kp4G1YQcn2KwU1i1j2_5CU_dN8_kTC-T2HdF_-ANV37PoNYyZ9TdRuKwArQfBlbHsyD5WC6KDLMGf7MxK-DTMuoPlZh3SP12POTw",
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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": "262bd550-3657-46c4-bafc-cce4c6f4e0cb"
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}
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{
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"aud": "orders-api",
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"exp": 1787539014,
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"iat": 1787538714,
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"iss": "http://localhost:9000",
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"jti": "1d94acbc-e245-40fb-a75d-05ab3bc294b6",
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"nbf": 1787538714,
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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": 1787538713,
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"azp": "demo-spa",
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"exp": 1787540514,
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"iat": 1787538714,
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"iss": "http://localhost:9000",
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"jti": "dc3bbe32-0e2a-450b-a65c-54c443a8570d",
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"preferred_username": "alice",
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"sid": "cHooV7cjkG-WKxd-MY2r434ItIaxpqrYGUOlCBV678w",
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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":["FactorGrantedAuthority [authority=FACTOR_BEARER, issuedAt=2026-08-24T02:31:54.540547140Z]","SCOPE_openid","ROLE_USER","SCOPE_orders.read","ROLE_ADMIN"],"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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