feat(sdk): expose base key

README.md

@@ -37,6 +37,12 @@ public class Example {
                     .platformEndpoint("https://your.cluster/")
                     .build();
 
+        // Fetch the platform base key (if configured)
+        sdk.getBaseKey().ifPresent(baseKey -> {
+            System.out.println(baseKey.getKasUri());
+            System.out.println(baseKey.getPublicKey().getKid());
+        });
+
         // Encrypt a file
         try (InputStream in = new FileInputStream("input.plaintext")) {
             Config.TDFConfig c = Config.newTDFConfig(Config.withDataAttributes("attr1", "attr2"));

pom.xml

@@ -18,6 +18,7 @@
         <protobuf.version>4.29.2</protobuf.version>
         <bouncycastle.version>1.82</bouncycastle.version>
         <ayza.version>10.0.0</ayza.version>
+        <bytebuddy.version>1.14.12</bytebuddy.version>
         <!-- JaCoCo Properties -->
         <jacoco.version>0.8.13</jacoco.version>
         <sonar.java.coveragePlugin>jacoco</sonar.java.coveragePlugin>
@@ -156,6 +157,20 @@
                 <artifactId>bcprov-jdk18on</artifactId>
                 <version>${bouncycastle.version}</version>
             </dependency>
+            <!--
+                Pin Byte Buddy for test-time Mockito instrumentation on newer JVMs (e.g. Java 21).
+                This does NOT add a runtime dependency; it only manages the version used by modules.
+            -->
+            <dependency>
+                <groupId>net.bytebuddy</groupId>
+                <artifactId>byte-buddy</artifactId>
+                <version>${bytebuddy.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>net.bytebuddy</groupId>
+                <artifactId>byte-buddy-agent</artifactId>
+                <version>${bytebuddy.version}</version>
+            </dependency>
         </dependencies>
     </dependencyManagement>
 

sdk/pom.xml

@@ -592,4 +592,4 @@
             </build>
         </profile>
     </profiles>
-</project>
+</project>

sdk/src/main/java/io/opentdf/platform/sdk/SDK.java

@@ -4,6 +4,7 @@
 
 import com.connectrpc.impl.ProtocolClient;
 import io.opentdf.platform.authorization.AuthorizationServiceClientInterface;
+import io.opentdf.platform.policy.SimpleKasKey;
 import io.opentdf.platform.policy.attributes.AttributesServiceClientInterface;
 import io.opentdf.platform.policy.kasregistry.KeyAccessServerRegistryServiceClientInterface;
 import io.opentdf.platform.policy.namespaces.NamespaceServiceClientInterface;
@@ -98,6 +99,15 @@ public Services getServices() {
         return this.services;
     }
 
+    /**
+     * Fetch the platform "base key" from the well-known configuration, if present.
+     * <p>
+     * This is read from the {@code base_key} field returned by {@code GetWellKnownConfiguration}.
+     */
+    public Optional<SimpleKasKey> getBaseKey() {
+        return Planner.fetchBaseKey(services.wellknown());
+    }
+
     public TDF.Reader loadTDF(SeekableByteChannel channel, Config.TDFReaderConfig config) throws SDKException, IOException {
         var tdf = new TDF(services);
         return tdf.loadTDF(channel, config, platformUrl);

sdk/src/test/java/io/opentdf/platform/sdk/SDKTest.java

@@ -1,8 +1,14 @@
 package io.opentdf.platform.sdk;
 
 import com.connectrpc.impl.ProtocolClient;
+import com.google.protobuf.Struct;
+import com.google.protobuf.Value;
+import io.opentdf.platform.policy.Algorithm;
+import io.opentdf.platform.wellknownconfiguration.GetWellKnownConfigurationResponse;
+import io.opentdf.platform.wellknownconfiguration.WellKnownServiceClientInterface;
 import org.apache.commons.compress.utils.SeekableInMemoryByteChannel;
 import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -30,6 +36,33 @@ void testReadingProtocolClient() {
         assertThat(sdk.getPlatformServicesClient()).isSameAs(platformServicesClient);
     }
 
+    @Test
+    void testGettingBaseKey() {
+        var platformServicesClient = mock(ProtocolClient.class);
+        var wellknownService = Mockito.mock(WellKnownServiceClientInterface.class);
+        var baseKeyJson = "{\"kas_url\":\"https://example.com/base_key\",\"public_key\":{\"algorithm\":\"ALGORITHM_RSA_2048\",\"kid\":\"thekid\",\"pem\": \"thepem\"}}";
+        var val = Value.newBuilder().setStringValue(baseKeyJson).build();
+        var config = Struct.newBuilder().putFields("base_key", val).build();
+        var response = GetWellKnownConfigurationResponse
+                .newBuilder()
+                .setConfiguration(config)
+                .build();
+
+        Mockito.when(wellknownService.getWellKnownConfigurationBlocking(Mockito.any(), Mockito.anyMap()))
+                .thenReturn(TestUtil.successfulUnaryCall(response));
+
+        var services = new FakeServicesBuilder().setWellknownService(wellknownService).build();
+        var sdk = new SDK(services, null, null, platformServicesClient, null);
+
+        var baseKey = sdk.getBaseKey();
+        assertThat(baseKey).isPresent();
+        var simpleKasKey = baseKey.get();
+        assertThat(simpleKasKey.getKasUri()).isEqualTo("https://example.com/base_key");
+        assertThat(simpleKasKey.getPublicKey().getAlgorithm()).isEqualTo(Algorithm.ALGORITHM_RSA_2048);
+        assertThat(simpleKasKey.getPublicKey().getKid()).isEqualTo("thekid");
+        assertThat(simpleKasKey.getPublicKey().getPem()).isEqualTo("thepem");
+    }
+
     @Test
     void testAuthorizationServiceClientV2() {
         var platformServicesClient = mock(ProtocolClient.class);
@@ -108,4 +141,4 @@ void testReadingRandomBytes() {
 
         assertThat(SDK.isTDF(new SeekableInMemoryByteChannel(tdf))).isFalse();
     }
-}
+}