feat: Temporary: Use email as fallback principal id when user_uuid is missing.

cloudplatform/security/src/main/java/com/sap/cloud/sdk/cloudplatform/security/principal/OidcAuthTokenPrincipalExtractor.java

@@ -16,6 +16,7 @@
 class OidcAuthTokenPrincipalExtractor implements PrincipalExtractor
 {
     private static final String JWT_USER_UUID_CLAIM = "user_uuid";
+    private static final String JWT_EMAIL_CLAIM = "email";
 
     @Override
     @Nonnull
@@ -43,11 +44,16 @@ private Try<String> tryGetPrincipalId( @Nonnull final DecodedJWT jwt )
         return Try.of(() -> {
             final Claim userUuidClaim = jwt.getClaim(JWT_USER_UUID_CLAIM);
 
-            if( userUuidClaim.isMissing() || userUuidClaim.isNull() ) {
-                throw new PrincipalAccessException("The current JWT does not contain the IAS user uuid.");
+            if( userUuidClaim != null && !userUuidClaim.isMissing() && !userUuidClaim.isNull() ) {
+                return userUuidClaim.asString();
             }
 
-            return userUuidClaim.asString();
+            final Claim emailClaim = jwt.getClaim(JWT_EMAIL_CLAIM);
+            if( emailClaim != null && !emailClaim.isMissing() && !emailClaim.isNull() ) {
+                return emailClaim.asString();
+            }
+
+            throw new PrincipalAccessException("The current JWT does not contain the IAS user uuid or an email.");
         });
     }
 }

cloudplatform/security/src/test/java/com/sap/cloud/sdk/cloudplatform/security/AuthTokenDecoderIasTest.java

@@ -202,4 +202,35 @@ void testCaseInsensitiveBearer()
         assertThat(jwt).isNotNull();
         assertThat(jwt.getClaim("user_uuid").asString()).isEqualTo("5a21dfa1-fd90-45ff-a5d3-d1cfa446d25a");
     }
+
+    @Test
+    void testDecodeSucceedsWithEmailOnly( @Nonnull final WireMockRuntimeInfo wm )
+    {
+        final Token tokenOnlyEmail =
+            JwtGenerator
+                .getInstance(Service.IAS, "2aba8ab2-edc3-4666-b2ed-90b2b47e60e3")
+                .withHeaderParameter(TokenHeader.KEY_ID, "testKey")
+                .withClaimValue("iss", wm.getHttpBaseUrl())
+                .withClaimValues("aud", "1668e3ce-e2b8-4d27-a05b-3db47e7a4152", "2aba8ab2-edc3-4666-b2ed-90b2b47e60e3")
+                .withClaimValue("sub", "sub-only-email")
+                // intentionally omit user_uuid
+                .withClaimValue("email", "[email protected]")
+                .withExpiration(OffsetDateTime.now().plusDays(1).toInstant())
+                .withPrivateKey(RSA_KEYS.getPrivate())
+                .createToken();
+
+        final String tokenValue = tokenOnlyEmail.getTokenValue();
+
+        final RequestHeaderContainer headers =
+            DefaultRequestHeaderContainer
+                .fromSingleValueMap(Collections.singletonMap(HttpHeaders.AUTHORIZATION, "Bearer " + tokenValue));
+
+        final AuthToken authToken = new AuthTokenDecoderDefault().decode(headers).getOrNull();
+
+        assertThat(authToken).isNotNull();
+
+        final DecodedJWT jwt = authToken.getJwt();
+        assertThat(jwt).isNotNull();
+        assertThat(jwt.getClaim("email").asString()).isEqualTo("[email protected]");
+    }
 }

cloudplatform/security/src/test/java/com/sap/cloud/sdk/cloudplatform/security/principal/OidcAuthTokenPrincipalExtractorTest.java

@@ -56,6 +56,16 @@ void testReadPrincipal()
         assertThat(principal.getPrincipalId()).isEqualTo("principal id");
     }
 
+    @Test
+    void testReadPrincipalFromEmailFallback()
+    {
+        mockAuthTokenFacade(JWT.create().withClaim("email", "[email protected]"));
+
+        final Principal principal = new OidcAuthTokenPrincipalExtractor().tryGetCurrentPrincipal().get();
+
+        assertThat(principal.getPrincipalId()).isEqualTo("[email protected]");
+    }
+
     private void mockAuthTokenFacadeWithMissingAuthToken()
     {
         AuthTokenAccessor.setAuthTokenFacade(() -> Try.failure(new AuthTokenAccessException("Auth token not mocked.")));

release_notes.md

@@ -14,7 +14,7 @@
 
 ### ✨ New Functionality
 
-- 
+- Temporary: Use `email` as fallback principal id when `user_uuid` is missing. Will switch to using `sub` once IAS exposes `idtype` (tracked in [SCICAI-1323](https://jira.tools.sap/browse/SCICAI-1323)).
 
 ### 📈 Improvements