diff --git a/gcloud-java-core/src/main/java/com/google/gcloud/AuthCredentials.java b/gcloud-java-core/src/main/java/com/google/gcloud/AuthCredentials.java
index 800fcf340689..afd785981ab9 100644
--- a/gcloud-java-core/src/main/java/com/google/gcloud/AuthCredentials.java
+++ b/gcloud-java-core/src/main/java/com/google/gcloud/AuthCredentials.java
@@ -28,6 +28,7 @@
 import com.google.api.client.json.jackson.JacksonFactory;
 import com.google.auth.http.HttpCredentialsAdapter;
 import com.google.auth.oauth2.GoogleCredentials;
+import com.google.auth.oauth2.ServiceAccountCredentials;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -212,7 +213,7 @@ public RestorableState<AuthCredentials> capture() {
     }
   }
 
-  private static class ApplicationDefaultAuthCredentials extends AuthCredentials {
+  public static class ApplicationDefaultAuthCredentials extends AuthCredentials {
 
     private GoogleCredentials googleCredentials;
 
@@ -255,6 +256,15 @@ protected HttpRequestInitializer httpRequestInitializer(HttpTransport transport,
       return new HttpCredentialsAdapter(googleCredentials.createScoped(scopes));
     }
 
+    public ServiceAccountAuthCredentials toServiceAccountCredentials() {
+      if (googleCredentials instanceof ServiceAccountCredentials) {
+        ServiceAccountCredentials credentials = (ServiceAccountCredentials) googleCredentials;
+        return new ServiceAccountAuthCredentials(credentials.getClientEmail(),
+            credentials.getPrivateKey());
+      }
+      return null;
+    }
+
     @Override
     public RestorableState<AuthCredentials> capture() {
       return STATE;
diff --git a/gcloud-java-storage/src/main/java/com/google/gcloud/storage/StorageImpl.java b/gcloud-java-storage/src/main/java/com/google/gcloud/storage/StorageImpl.java
index fa059254eddb..8ae3948a7576 100644
--- a/gcloud-java-storage/src/main/java/com/google/gcloud/storage/StorageImpl.java
+++ b/gcloud-java-storage/src/main/java/com/google/gcloud/storage/StorageImpl.java
@@ -43,6 +43,8 @@
 import com.google.common.hash.Hashing;
 import com.google.common.io.BaseEncoding;
 import com.google.common.primitives.Ints;
+import com.google.gcloud.AuthCredentials;
+import com.google.gcloud.AuthCredentials.ApplicationDefaultAuthCredentials;
 import com.google.gcloud.AuthCredentials.ServiceAccountAuthCredentials;
 import com.google.gcloud.PageImpl;
 import com.google.gcloud.BaseService;
@@ -584,9 +586,15 @@ public URL signUrl(BlobInfo blobInfo, long duration, TimeUnit unit, SignUrlOptio
     ServiceAccountAuthCredentials cred =
         (ServiceAccountAuthCredentials) optionMap.get(SignUrlOption.Option.SERVICE_ACCOUNT_CRED);
     if (cred == null) {
-      checkArgument(options().authCredentials() instanceof ServiceAccountAuthCredentials,
-          "Signing key was not provided and could not be derived");
-      cred = (ServiceAccountAuthCredentials) this.options().authCredentials();
+      AuthCredentials serviceCred = this.options().authCredentials();
+      if (serviceCred instanceof ServiceAccountAuthCredentials) {
+        cred = (ServiceAccountAuthCredentials) serviceCred;
+      } else {
+        if (serviceCred instanceof ApplicationDefaultAuthCredentials) {
+          cred = ((ApplicationDefaultAuthCredentials) serviceCred).toServiceAccountCredentials();
+        }
+      }
+      checkArgument(cred != null, "Signing key was not provided and could not be derived");
     }
     // construct signature - see https://cloud.google.com/storage/docs/access-control#Signed-URLs
     StringBuilder stBuilder = new StringBuilder();
diff --git a/gcloud-java-storage/src/main/java/com/google/gcloud/storage/testing/RemoteGcsHelper.java b/gcloud-java-storage/src/main/java/com/google/gcloud/storage/testing/RemoteGcsHelper.java
index b15768cffa98..f5cdae83f999 100644
--- a/gcloud-java-storage/src/main/java/com/google/gcloud/storage/testing/RemoteGcsHelper.java
+++ b/gcloud-java-storage/src/main/java/com/google/gcloud/storage/testing/RemoteGcsHelper.java
@@ -45,8 +45,6 @@ public class RemoteGcsHelper {
 
   private static final Logger log = Logger.getLogger(RemoteGcsHelper.class.getName());
   private static final String BUCKET_NAME_PREFIX = "gcloud-test-bucket-temp-";
-  private static final String PROJECT_ID_ENV_VAR = "GCLOUD_TESTS_PROJECT_ID";
-  private static final String PRIVATE_KEY_ENV_VAR = "GCLOUD_TESTS_KEY";
   private final StorageOptions options;
 
   private RemoteGcsHelper(StorageOptions options) {
@@ -107,13 +105,7 @@ public static RemoteGcsHelper create(String projectId, InputStream keyStream)
       StorageOptions storageOptions = StorageOptions.builder()
           .authCredentials(AuthCredentials.createForJson(keyStream))
           .projectId(projectId)
-          .retryParams(RetryParams.builder()
-              .retryMaxAttempts(10)
-              .retryMinAttempts(6)
-              .maxRetryDelayMillis(30000)
-              .totalRetryPeriodMillis(120000)
-              .initialRetryDelayMillis(250)
-              .build())
+          .retryParams(retryParams())
           .connectTimeout(60000)
           .readTimeout(60000)
           .build();
@@ -145,41 +137,30 @@ public static RemoteGcsHelper create(String projectId, String keyPath)
         log.log(Level.WARNING, ex.getMessage());
       }
       throw GcsHelperException.translate(ex);
-    } catch (IOException ex) {
-      if (log.isLoggable(Level.WARNING)) {
-        log.log(Level.WARNING, ex.getMessage());
-      }
-      throw GcsHelperException.translate(ex);
     }
   }
 
   /**
-   * Creates a {@code RemoteGcsHelper} object. Project id and path to JSON key are read from two
-   * environment variables: {@code GCLOUD_TESTS_PROJECT_ID} and {@code GCLOUD_TESTS_KEY}.
-   *
-   * @return A {@code RemoteGcsHelper} object for the provided options.
-   * @throws com.google.gcloud.storage.testing.RemoteGcsHelper.GcsHelperException if environment
-   *     variables {@code GCLOUD_TESTS_PROJECT_ID} and {@code GCLOUD_TESTS_KEY} are not set or if
-   *     the file pointed by {@code GCLOUD_TESTS_KEY} does not exist
+   * Creates a {@code RemoteGcsHelper} object using default project id and authentication
+   * credentials.
    */
   public static RemoteGcsHelper create() throws GcsHelperException {
-    String projectId = System.getenv(PROJECT_ID_ENV_VAR);
-    String keyPath = System.getenv(PRIVATE_KEY_ENV_VAR);
-    if (projectId == null) {
-      String message = "Environment variable " + PROJECT_ID_ENV_VAR + " not set";
-      if (log.isLoggable(Level.WARNING)) {
-        log.log(Level.WARNING, message);
-      }
-      throw new GcsHelperException(message);
-    }
-    if (keyPath == null) {
-      String message = "Environment variable " + PRIVATE_KEY_ENV_VAR + " not set";
-      if (log.isLoggable(Level.WARNING)) {
-        log.log(Level.WARNING, message);
-      }
-      throw new GcsHelperException(message);
-    }
-    return create(projectId, keyPath);
+    StorageOptions storageOptions = StorageOptions.builder()
+        .retryParams(retryParams())
+        .connectTimeout(60000)
+        .readTimeout(60000)
+        .build();
+    return new RemoteGcsHelper(storageOptions);
+  }
+
+  private static RetryParams retryParams() {
+    return RetryParams.builder()
+        .retryMaxAttempts(10)
+        .retryMinAttempts(6)
+        .maxRetryDelayMillis(30000)
+        .totalRetryPeriodMillis(120000)
+        .initialRetryDelayMillis(250)
+        .build();
   }
 
   private static class DeleteBucketTask implements Callable<Boolean> {
diff --git a/utilities/integration_test_env.sh b/utilities/integration_test_env.sh
index f7aca1a8a623..a1bebe4dcb69 100755
--- a/utilities/integration_test_env.sh
+++ b/utilities/integration_test_env.sh
@@ -1,3 +1,3 @@
 # Export test env variables
-export GCLOUD_TESTS_PROJECT_ID="gcloud-devel"
-export GCLOUD_TESTS_KEY=$TRAVIS_BUILD_DIR/signing-tools/gcloud-devel-travis.json
+export GCLOUD_PROJECT="gcloud-devel"
+export GOOGLE_APPLICATION_CREDENTIALS=$TRAVIS_BUILD_DIR/signing-tools/gcloud-devel-travis.json