Fuzzing: Add fuzzer for dev.sigstore.bundle package

fuzzing/src/main/java/fuzzing/BundleFuzzer.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2023 The Sigstore Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package fuzzing;
+
+import com.code_intelligence.jazzer.api.FuzzedDataProvider;
+import dev.sigstore.bundle.BundleFactory;
+import dev.sigstore.bundle.BundleParseException;
+import dev.sigstore.bundle.BundleVerifier;
+import java.io.StringReader;
+
+public class BundleFuzzer {
+  public static void fuzzerTestOneInput(FuzzedDataProvider data) {
+    try {
+      Boolean choice = data.consumeBoolean();
+      String string = data.consumeRemainingAsString();
+
+      if (choice) {
+        BundleFactory.createBundle(BundleFactory.readBundle(new StringReader(string)));
+      } else {
+        BundleVerifier.findMissingFields(string);
+      }
+    } catch (BundleParseException | IllegalArgumentException e) {
+      // Known exception
+    }
+  }
+}