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https://issues.apache.org/jira/browse/KAFKA-14496?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Manikumar updated KAFKA-14496:
------------------------------
Fix Version/s: 3.4.0
3.3.2
> Wrong Base64 encoder used by OIDC OAuthBearerLoginCallbackHandler
> -----------------------------------------------------------------
>
> Key: KAFKA-14496
> URL: https://issues.apache.org/jira/browse/KAFKA-14496
> Project: Kafka
> Issue Type: Bug
> Components: clients
> Affects Versions: 3.3.1
> Reporter: Endre Vig
> Priority: Major
> Fix For: 3.4.0, 3.3.2
>
> Attachments: base64test.zip
>
>
> Currently our team is setting up a blueprint for our Kafka
> consumers/producers to provide guidelines on how to connect to our broker
> using the OIDC security mechanism. The blueprint is written in Java using the
> latest 3.3.1 Kafka library dependencies managed by Spring Boot 3.0.0.
> While trying to use the new built-in
> {{org.apache.kafka.common.security.oauthbearer.secured.OAuthBearerLoginCallbackHandler}}
> introduced by [KIP-768: Extend SASL/OAUTHBEARER with Support for
> OIDC|https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=186877575],
> we've noticed that some calls to retrieve the token work out well, while
> some of them (seemingly randomly) are failing with 401 Unauthorized.
> After some debugging we've got to the conclusion that the faulty behavior is
> caused by
> {{org.apache.kafka.common.security.oauthbearer.secured.HttpAccessTokenRetriever#formatAuthorizationHeader:}}
> {code:java}
> static String formatAuthorizationHeader(String clientId, String clientSecret)
> {
> clientId = sanitizeString("the token endpoint request client ID
> parameter", clientId);
> clientSecret = sanitizeString("the token endpoint request client secret
> parameter", clientSecret);
>
> String s = String.format("%s:%s", clientId, clientSecret);
> String encoded = Base64.getUrlEncoder().encodeToString(Utils.utf8(s));
> return String.format("Basic %s", encoded);
> } {code}
> The above code is using {{java.util.Base64#getUrlEncoder}} on line 311 to
> encode the authorization header value, which is using the alphabet described
> in [section 5 of the RFC|https://www.rfc-editor.org/rfc/rfc4648#section-5]
> during the encoding algorithm. As stated by the Basic Authentication Scheme
> [definition|https://www.rfc-editor.org/rfc/rfc7617#section-2] however,
> [section 4 of the RFC|https://www.rfc-editor.org/rfc/rfc4648#section-4]
> should be used:
> ??4. and obtains the basic-credentials by encoding this octet sequence using
> Base64 ([RFC4648], Section 4) into a sequence of US-ASCII characters
> ([RFC0020]).??
> The difference between the 2 alphabets are only on two characters (62: '+'
> vs. '-' and 63: '/' vs. '_'), that's why the 401 Unauthorized response arises
> only for certain credential values.
> Here's a concrete example use case:
>
> {code:java}
> String s = String.format("%s:%s", "SOME_RANDOM_LONG_USER_01234",
> "9Q|0`8i~ute-n9ksjLWb\\50\"AX@UUED5E");
> System.out.println(Base64.getUrlEncoder().encodeToString(Utils.utf8(s)));
> {code}
> would print out:
> {code:java}
> U09NRV9SQU5ET01fTE9OR19VU0VSXzAxMjM0OjlRfDBgOGl-dXRlLW45a3NqTFdiXDUwIkFYQFVVRUQ1RQ==
> {code}
> while
> {code:java}
> String s = String.format("%s:%s", "SOME_RANDOM_LONG_USER_01234",
> "9Q|0`8i~ute-n9ksjLWb\\50\"AX@UUED5E");
> System.out.println(Base64.getEncoder().encodeToString(Utils.utf8(s))); {code}
> would give:
> {code:java}
> U09NRV9SQU5ET01fTE9OR19VU0VSXzAxMjM0OjlRfDBgOGl+dXRlLW45a3NqTFdiXDUwIkFYQFVVRUQ1RQ==
> {code}
> Please notice the '-' vs. '+' characters.
>
> The 2 code snippets above would not behave differently for other credentials,
> where the encoded result doesn't use the 62nd character of the alphabet:
> {code:java}
> String s = String.format("%s:%s", "SHORT_USER_01234",
> "9Q|0`8i~ute-n9ksjLWb\\50\"AX@UUED5E");
> System.out.println(Base64.getEncoder().encodeToString(Utils.utf8(s))); {code}
> {code:java}
> U0hPUlRfVVNFUl8wMTIzNDo5UXwwYDhpfnV0ZS1uOWtzakxXYlw1MCJBWEBVVUVENUU=
> {code}
>
> As a *conclusion* I would suggest that line 311 of
> {{HttpAccessTokenRetriever}} should be modified to use
> {{Base64.getEncoder().encodeToString(...)}} instead of
> {{Base64.getUrlEncoder().encodeToString(...).}}
>
> I'm attaching a short sample application with tests proving that the above
> encoding method is rejected by the standard Spring Security HTTP basic
> authentication as well.
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