Measuring re-identification and disclosure risk

Risk analysis is the process of analyzing sensitive data to find properties that might increase the risk of subjects being identified. You can use risk analysis methods before de-identification to help determine an effective de-identification strategy or after de-identification to monitor for any changes or outliers.

Cloud Data Loss Prevention (DLP) can compute three risk metrics: k-anonymity, l-diversity, k-map, and δ-presence. If you're not familiar with risk analysis or any of these metrics, see the risk analysis concept topic before continuing on.

This topic gives an overview of how to use Cloud DLP for risk analysis of structured data using any of these metrics.

Risk analysis using Cloud DLP

Cloud DLP can analyze your structured data stored in BigQuery tables and compute the following privacy metrics:

Cloud DLP performs risk analysis whenever a risk analysis job runs. You must create the job first. To create a risk analysis job, you send a request to the following URL:

POST https://dlp.googleapis.com/v2/{parent=projects/*}/dlpJobs

The request contains a RiskAnalysisJobConfig object, which is composed of the following:

Computing k-anonymity with Cloud DLP

K-anonymity is a property of a dataset that indicates the re-identifiability of its records. A dataset is k-anonymous if quasi-identifiers for each person in the dataset are identical to at least k – 1 other people also in the dataset.

You can compute the k-anonymity value based on one or more columns, or fields, by first following the instructions in the previous section, Risk analysis using Cloud DLP.

Within the KAnonymityConfig object, you specify the following:

  • quasiIds[]: One or more quasi-identifiers (FieldId objects) to scan and use to compute k-anonymity. When you specify multiple quasi-identifiers, they are considered a single composite key. Structs and repeated data types are not supported, but nested fields are supported as long as they are not structs themselves or nested within a repeated field.
  • entityId: Optional identifier value that, when set, indicates that all rows corresponding to each distinct entityId should be grouped together for k-anonymity computation. Typically, an entityId will be a column that represents a unique user, like a customer ID or a user ID. When an entityId appears on several rows with different quasi-identifier values, these rows will be joined to form a multiset that will be used as the quasi-identifiers for that entity. For more information about entity IDs, see Entity IDs and computing k-anonymity in the Risk analysis conceptual topic.

Code examples

Following is sample code in several languages that demonstrates how to use Cloud DLP to compute a k-anonymity value.

Java

/**
 * Calculate k-anonymity for quasi-identifiers in a BigQuery table using the DLP API.
 *
 * @param projectId The Google Cloud Platform project ID to run the API call under.
 * @param datasetId The BigQuery dataset to analyze.
 * @param tableId The BigQuery table to analyze.
 * @param quasiIds The names of columns that form a composite key ('quasi-identifiers').
 * @param topicId The name of the Pub/Sub topic to notify once the job completes
 * @param subscriptionId The name of the Pub/Sub subscription to use when listening for job
 *     completion status.
 */
private static void calculateKAnonymity(
    String projectId,
    String datasetId,
    String tableId,
    List<String> quasiIds,
    String topicId,
    String subscriptionId)
    throws Exception {
  // Instantiates a client
  try (DlpServiceClient dlpServiceClient = DlpServiceClient.create()) {

    List<FieldId> quasiIdFields =
        quasiIds
            .stream()
            .map(columnName -> FieldId.newBuilder().setName(columnName).build())
            .collect(Collectors.toList());

    KAnonymityConfig kanonymityConfig =
        KAnonymityConfig.newBuilder().addAllQuasiIds(quasiIdFields).build();

    BigQueryTable bigQueryTable =
        BigQueryTable.newBuilder()
            .setProjectId(projectId)
            .setDatasetId(datasetId)
            .setTableId(tableId)
            .build();

    PrivacyMetric privacyMetric =
        PrivacyMetric.newBuilder().setKAnonymityConfig(kanonymityConfig).build();

    String topicName = String.format("projects/%s/topics/%s", projectId, topicId);

    PublishToPubSub publishToPubSub = PublishToPubSub.newBuilder().setTopic(topicName).build();

    // Create action to publish job status notifications over Google Cloud Pub/Sub
    Action action = Action.newBuilder().setPubSub(publishToPubSub).build();

    RiskAnalysisJobConfig riskAnalysisJobConfig =
        RiskAnalysisJobConfig.newBuilder()
            .setSourceTable(bigQueryTable)
            .setPrivacyMetric(privacyMetric)
            .addActions(action)
            .build();

    CreateDlpJobRequest createDlpJobRequest =
        CreateDlpJobRequest.newBuilder()
            .setParent(ProjectName.of(projectId).toString())
            .setRiskJob(riskAnalysisJobConfig)
            .build();

    DlpJob dlpJob = dlpServiceClient.createDlpJob(createDlpJobRequest);
    String dlpJobName = dlpJob.getName();

    final SettableApiFuture<Boolean> done = SettableApiFuture.create();

    // Set up a Pub/Sub subscriber to listen on the job completion status
    Subscriber subscriber =
        Subscriber.newBuilder(
                ProjectSubscriptionName.newBuilder()
                    .setProject(projectId)
                    .setSubscription(subscriptionId)
                    .build(),
          (pubsubMessage, ackReplyConsumer) -> {
            if (pubsubMessage.getAttributesCount() > 0
                && pubsubMessage.getAttributesMap().get("DlpJobName").equals(dlpJobName)) {
              // notify job completion
              done.set(true);
              ackReplyConsumer.ack();
            }
          })
            .build();
    subscriber.startAsync();

    // Wait for job completion semi-synchronously
    // For long jobs, consider using a truly asynchronous execution model such as Cloud Functions
    try {
      done.get(1, TimeUnit.MINUTES);
      Thread.sleep(500); // Wait for the job to become available
    } catch (TimeoutException e) {
      System.out.println("Unable to verify job completion.");
    }

    // Retrieve completed job status
    DlpJob completedJob =
        dlpServiceClient.getDlpJob(GetDlpJobRequest.newBuilder().setName(dlpJobName).build());

    System.out.println("Job status: " + completedJob.getState());
    AnalyzeDataSourceRiskDetails riskDetails = completedJob.getRiskDetails();

    KAnonymityResult kanonymityResult = riskDetails.getKAnonymityResult();
    for (KAnonymityHistogramBucket result :
        kanonymityResult.getEquivalenceClassHistogramBucketsList()) {
      System.out.printf(
          "Bucket size range: [%d, %d]\n",
          result.getEquivalenceClassSizeLowerBound(), result.getEquivalenceClassSizeUpperBound());

      for (KAnonymityEquivalenceClass bucket : result.getBucketValuesList()) {
        List<String> quasiIdValues =
            bucket
                .getQuasiIdsValuesList()
                .stream()
                .map(v -> v.toString())
                .collect(Collectors.toList());

        System.out.println("\tQuasi-ID values: " + String.join(", ", quasiIdValues));
        System.out.println("\tClass size: " + bucket.getEquivalenceClassSize());
      }
    }
  } catch (Exception e) {
    System.out.println("Error in calculateKAnonymity: " + e.getMessage());
  }
}

Node.js

// Import the Google Cloud client libraries
const DLP = require('@google-cloud/dlp');
const {PubSub} = require('@google-cloud/pubsub');

// Instantiates clients
const dlp = new DLP.DlpServiceClient();
const pubsub = new PubSub();

// The project ID to run the API call under
// const callingProjectId = process.env.GCLOUD_PROJECT;

// The project ID the table is stored under
// This may or (for public datasets) may not equal the calling project ID
// const tableProjectId = process.env.GCLOUD_PROJECT;

// The ID of the dataset to inspect, e.g. 'my_dataset'
// const datasetId = 'my_dataset';

// The ID of the table to inspect, e.g. 'my_table'
// const tableId = 'my_table';

// The name of the Pub/Sub topic to notify once the job completes
// TODO(developer): create a Pub/Sub topic to use for this
// const topicId = 'MY-PUBSUB-TOPIC'

// The name of the Pub/Sub subscription to use when listening for job
// completion notifications
// TODO(developer): create a Pub/Sub subscription to use for this
// const subscriptionId = 'MY-PUBSUB-SUBSCRIPTION'

// A set of columns that form a composite key ('quasi-identifiers')
// const quasiIds = [{ name: 'age' }, { name: 'city' }];

const sourceTable = {
  projectId: tableProjectId,
  datasetId: datasetId,
  tableId: tableId,
};

// Construct request for creating a risk analysis job
const request = {
  parent: dlp.projectPath(callingProjectId),
  riskJob: {
    privacyMetric: {
      kAnonymityConfig: {
        quasiIds: quasiIds,
      },
    },
    sourceTable: sourceTable,
    actions: [
      {
        pubSub: {
          topic: `projects/${callingProjectId}/topics/${topicId}`,
        },
      },
    ],
  },
};

// Create helper function for unpacking values
const getValue = obj => obj[Object.keys(obj)[0]];

try {
  // Run risk analysis job
  const [topicResponse] = await pubsub.topic(topicId).get();
  const subscription = await topicResponse.subscription(subscriptionId);
  const [jobsResponse] = await dlp.createDlpJob(request);
  const jobName = jobsResponse.name;
  // Watch the Pub/Sub topic until the DLP job finishes
  await new Promise((resolve, reject) => {
    const messageHandler = message => {
      if (message.attributes && message.attributes.DlpJobName === jobName) {
        message.ack();
        subscription.removeListener('message', messageHandler);
        subscription.removeListener('error', errorHandler);
        resolve(jobName);
      } else {
        message.nack();
      }
    };

    const errorHandler = err => {
      subscription.removeListener('message', messageHandler);
      subscription.removeListener('error', errorHandler);
      reject(err);
    };

    subscription.on('message', messageHandler);
    subscription.on('error', errorHandler);
  });
  setTimeout(() => {
    console.log(` Waiting for DLP job to fully complete`);
  }, 500);
  const [job] = await dlp.getDlpJob({name: jobName});
  const histogramBuckets =
    job.riskDetails.kAnonymityResult.equivalenceClassHistogramBuckets;

  histogramBuckets.forEach((histogramBucket, histogramBucketIdx) => {
    console.log(`Bucket ${histogramBucketIdx}:`);
    console.log(
      `  Bucket size range: [${
        histogramBucket.equivalenceClassSizeLowerBound
      }, ${histogramBucket.equivalenceClassSizeUpperBound}]`
    );

    histogramBucket.bucketValues.forEach(valueBucket => {
      const quasiIdValues = valueBucket.quasiIdsValues
        .map(getValue)
        .join(', ');
      console.log(`  Quasi-ID values: {${quasiIdValues}}`);
      console.log(`  Class size: ${valueBucket.equivalenceClassSize}`);
    });
  });
} catch (err) {
  console.log(`Error in kAnonymityAnalysis: ${err.message || err}`);
}

Python

def k_anonymity_analysis(project, table_project_id, dataset_id, table_id,
                         topic_id, subscription_id, quasi_ids, timeout=300):
    """Uses the Data Loss Prevention API to compute the k-anonymity of a
        column set in a Google BigQuery table.
    Args:
        project: The Google Cloud project id to use as a parent resource.
        table_project_id: The Google Cloud project id where the BigQuery table
            is stored.
        dataset_id: The id of the dataset to inspect.
        table_id: The id of the table to inspect.
        topic_id: The name of the Pub/Sub topic to notify once the job
            completes.
        subscription_id: The name of the Pub/Sub subscription to use when
            listening for job completion notifications.
        quasi_ids: A set of columns that form a composite key.
        timeout: The number of seconds to wait for a response from the API.

    Returns:
        None; the response from the API is printed to the terminal.
    """

    # Import the client library.
    import google.cloud.dlp

    # This sample additionally uses Cloud Pub/Sub to receive results from
    # potentially long-running operations.
    import google.cloud.pubsub

    # Create helper function for unpacking values
    def get_values(obj):
        return int(obj.integer_value)

    def callback(message):
        if (message.attributes['DlpJobName'] == operation.name):
            # This is the message we're looking for, so acknowledge it.
            message.ack()

            # Now that the job is done, fetch the results and print them.
            job = dlp.get_dlp_job(operation.name)
            histogram_buckets = (job.risk_details
                                    .k_anonymity_result
                                    .equivalence_class_histogram_buckets)
            # Print bucket stats
            for i, bucket in enumerate(histogram_buckets):
                print('Bucket {}:'.format(i))
                if bucket.equivalence_class_size_lower_bound:
                    print('   Bucket size range: [{}, {}]'.format(
                        bucket.equivalence_class_size_lower_bound,
                        bucket.equivalence_class_size_upper_bound))
                    for value_bucket in bucket.bucket_values:
                        print('   Quasi-ID values: {}'.format(
                            map(get_values, value_bucket.quasi_ids_values)
                        ))
                        print('   Class size: {}'.format(
                            value_bucket.equivalence_class_size))
            subscription.set_result(None)
        else:
            # This is not the message we're looking for.
            message.drop()

    # Instantiate a client.
    dlp = google.cloud.dlp.DlpServiceClient()

    # Convert the project id into a full resource id.
    parent = dlp.project_path(project)

    # Location info of the BigQuery table.
    source_table = {
        'project_id': table_project_id,
        'dataset_id': dataset_id,
        'table_id': table_id
    }

    # Convert quasi id list to Protobuf type
    def map_fields(field):
        return {'name': field}

    quasi_ids = map(map_fields, quasi_ids)

    # Tell the API where to send a notification when the job is complete.
    actions = [{
        'pub_sub': {'topic': '{}/topics/{}'.format(parent, topic_id)}
    }]

    # Configure risk analysis job
    # Give the name of the numeric column to compute risk metrics for
    risk_job = {
        'privacy_metric': {
            'k_anonymity_config': {
                'quasi_ids': quasi_ids
            }
        },
        'source_table': source_table,
        'actions': actions
    }

    # Create a Pub/Sub client and find the subscription. The subscription is
    # expected to already be listening to the topic.
    subscriber = google.cloud.pubsub.SubscriberClient()
    subscription_path = subscriber.subscription_path(
        project, subscription_id)
    subscription = subscriber.subscribe(subscription_path, callback)

    # Call API to start risk analysis job
    operation = dlp.create_dlp_job(parent, risk_job=risk_job)

    try:
        subscription.result(timeout=timeout)
    except TimeoutError:
        print('No event received before the timeout. Please verify that the '
              'subscription provided is subscribed to the topic provided.')
        subscription.close()

Go

// riskKAnonymity computes the risk of the given columns using K Anonymity.
func riskKAnonymity(w io.Writer, client *dlp.Client, project, dataProject, pubSubTopic, pubSubSub, datasetID, tableID string, columnNames ...string) {
	ctx := context.Background()

	// Create a PubSub Client used to listen for when the inspect job finishes.
	pClient, err := pubsub.NewClient(ctx, project)
	if err != nil {
		log.Fatalf("Error creating PubSub client: %v", err)
	}
	defer pClient.Close()

	// Create a PubSub subscription we can use to listen for messages.
	s, err := setupPubSub(ctx, pClient, project, pubSubTopic, pubSubSub)
	if err != nil {
		log.Fatalf("Error setting up PubSub: %v\n", err)
	}

	// topic is the PubSub topic string where messages should be sent.
	topic := "projects/" + project + "/topics/" + pubSubTopic

	// Build the QuasiID slice.
	var q []*dlppb.FieldId
	for _, c := range columnNames {
		q = append(q, &dlppb.FieldId{Name: c})
	}

	// Create a configured request.
	req := &dlppb.CreateDlpJobRequest{
		Parent: "projects/" + project,
		Job: &dlppb.CreateDlpJobRequest_RiskJob{
			RiskJob: &dlppb.RiskAnalysisJobConfig{
				// PrivacyMetric configures what to compute.
				PrivacyMetric: &dlppb.PrivacyMetric{
					Type: &dlppb.PrivacyMetric_KAnonymityConfig_{
						KAnonymityConfig: &dlppb.PrivacyMetric_KAnonymityConfig{
							QuasiIds: q,
						},
					},
				},
				// SourceTable describes where to find the data.
				SourceTable: &dlppb.BigQueryTable{
					ProjectId: dataProject,
					DatasetId: datasetID,
					TableId:   tableID,
				},
				// Send a message to PubSub using Actions.
				Actions: []*dlppb.Action{
					{
						Action: &dlppb.Action_PubSub{
							PubSub: &dlppb.Action_PublishToPubSub{
								Topic: topic,
							},
						},
					},
				},
			},
		},
	}
	// Create the risk job.
	j, err := client.CreateDlpJob(context.Background(), req)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Fprintf(w, "Created job: %v\n", j.GetName())

	// Wait for the risk job to finish by waiting for a PubSub message.
	ctx, cancel := context.WithCancel(ctx)
	err = s.Receive(ctx, func(ctx context.Context, msg *pubsub.Message) {
		// If this is the wrong job, do not process the result.
		if msg.Attributes["DlpJobName"] != j.GetName() {
			msg.Nack()
			return
		}
		msg.Ack()
		time.Sleep(500 * time.Millisecond)
		j, err := client.GetDlpJob(ctx, &dlppb.GetDlpJobRequest{
			Name: j.GetName(),
		})
		if err != nil {
			log.Fatalf("Error getting completed job: %v\n", err)
		}
		h := j.GetRiskDetails().GetKAnonymityResult().GetEquivalenceClassHistogramBuckets()
		for i, b := range h {
			fmt.Fprintf(w, "Histogram bucket %v\n", i)
			fmt.Fprintf(w, "  Size range: [%v,%v]\n", b.GetEquivalenceClassSizeLowerBound(), b.GetEquivalenceClassSizeUpperBound())
			fmt.Fprintf(w, "  %v unique values total\n", b.GetBucketSize())
			for _, v := range b.GetBucketValues() {
				var qvs []string
				for _, qv := range v.GetQuasiIdsValues() {
					qvs = append(qvs, qv.String())
				}
				fmt.Fprintf(w, "    QuasiID values: %s\n", strings.Join(qvs, ", "))
				fmt.Fprintf(w, "    Class size: %v\n", v.GetEquivalenceClassSize())
			}
		}
		// Stop listening for more messages.
		cancel()
	})
	if err != nil {
		log.Fatalf("Error receiving from PubSub: %v\n", err)
	}
}

PHP

/**
 * Computes the k-anonymity of a column set in a Google BigQuery table.
 */
use Google\Cloud\Core\ExponentialBackoff;
use Google\Cloud\Dlp\V2\DlpServiceClient;
use Google\Cloud\Dlp\V2\RiskAnalysisJobConfig;
use Google\Cloud\Dlp\V2\BigQueryTable;
use Google\Cloud\Dlp\V2\DlpJob\JobState;
use Google\Cloud\Dlp\V2\Action;
use Google\Cloud\Dlp\V2\Action\PublishToPubSub;
use Google\Cloud\Dlp\V2\PrivacyMetric\KAnonymityConfig;
use Google\Cloud\Dlp\V2\PrivacyMetric;
use Google\Cloud\Dlp\V2\FieldId;
use Google\Cloud\PubSub\PubSubClient;

/** Uncomment and populate these variables in your code */
// $callingProjectId = 'The project ID to run the API call under';
// $dataProjectId = 'The project ID containing the target Datastore';
// $topicId = 'The name of the Pub/Sub topic to notify once the job completes';
// $subscriptionId = 'The name of the Pub/Sub subscription to use when listening for job';
// $datasetId = 'The ID of the dataset to inspect';
// $tableId = 'The ID of the table to inspect';
// $quasiIdNames = 'Comma-separated list of columns that form a composite key (quasi-identifiers)';

// Instantiate a client.
$dlp = new DlpServiceClient([
    'projectId' => $callingProjectId,
]);
$pubsub = new PubSubClient([
    'projectId' => $callingProjectId,
]);
$topic = $pubsub->topic($topicId);

// Construct risk analysis config
$quasiIds = array_map(
    function ($id) {
        return (new FieldId())->setName($id);
    },
    explode(',', $quasiIdNames)
);

$statsConfig = (new KAnonymityConfig())
    ->setQuasiIds($quasiIds);

$privacyMetric = (new PrivacyMetric())
    ->setKAnonymityConfig($statsConfig);

// Construct items to be analyzed
$bigqueryTable = (new BigQueryTable())
    ->setProjectId($dataProjectId)
    ->setDatasetId($datasetId)
    ->setTableId($tableId);

// Construct the action to run when job completes
$pubSubAction = (new PublishToPubSub())
    ->setTopic($topic->name());

$action = (new Action())
    ->setPubSub($pubSubAction);

// Construct risk analysis job config to run
$riskJob = (new RiskAnalysisJobConfig())
    ->setPrivacyMetric($privacyMetric)
    ->setSourceTable($bigqueryTable)
    ->setActions([$action]);

// Listen for job notifications via an existing topic/subscription.
$subscription = $topic->subscription($subscriptionId);

// Submit request
$parent = $dlp->projectName($callingProjectId);
$job = $dlp->createDlpJob($parent, [
    'riskJob' => $riskJob
]);

// Poll Pub/Sub using exponential backoff until job finishes
$backoff = new ExponentialBackoff(20);
$backoff->execute(function () use ($subscription, $dlp, &$job) {
    printf('Waiting for job to complete' . PHP_EOL);
    foreach ($subscription->pull() as $message) {
        if (isset($message->attributes()['DlpJobName']) &&
            $message->attributes()['DlpJobName'] === $job->getName()) {
            $subscription->acknowledge($message);
            // Get the updated job. Loop to avoid race condition with DLP API.
            do {
                $job = $dlp->getDlpJob($job->getName());
            } while ($job->getState() == JobState::RUNNING);
            return true;
        }
    }
    throw new Exception('Job has not yet completed');
});

// Print finding counts
printf('Job %s status: %s' . PHP_EOL, $job->getName(), JobState::name($job->getState()));
switch ($job->getState()) {
    case JobState::DONE:
        $histBuckets = $job->getRiskDetails()->getKAnonymityResult()->getEquivalenceClassHistogramBuckets();

        foreach ($histBuckets as $bucketIndex => $histBucket) {
            // Print bucket stats
            printf('Bucket %s:' . PHP_EOL, $bucketIndex);
            printf(
                '  Bucket size range: [%s, %s]' . PHP_EOL,
                $histBucket->getEquivalenceClassSizeLowerBound(),
                $histBucket->getEquivalenceClassSizeUpperBound()
            );

            // Print bucket values
            foreach ($histBucket->getBucketValues() as $percent => $valueBucket) {
                // Pretty-print quasi-ID values
                print('  Quasi-ID values:' . PHP_EOL);
                foreach ($valueBucket->getQuasiIdsValues() as $index => $value) {
                    print('    ' . $value->serializeToJsonString() . PHP_EOL);
                }
                printf(
                    '  Class size: %s' . PHP_EOL,
                    $valueBucket->getEquivalenceClassSize()
                );
            }
        }

        break;
    case JobState::FAILED:
        printf('Job %s had errors:' . PHP_EOL, $job->getName());
        $errors = $job->getErrors();
        foreach ($errors as $error) {
            var_dump($error->getDetails());
        }
        break;
    default:
        printf('Unexpected job state. Most likely, the job is either running or has not yet started.');
}

C#

public static object KAnonymity(
    string callingProjectId,
    string tableProjectId,
    string datasetId,
    string tableId,
    string topicId,
    string subscriptionId,
    IEnumerable<FieldId> quasiIds)
{
    DlpServiceClient dlp = DlpServiceClient.Create();

    // Construct + submit the job
    var KAnonymityConfig = new KAnonymityConfig
    {
        QuasiIds = { quasiIds }
    };

    var config = new RiskAnalysisJobConfig
    {
        PrivacyMetric = new PrivacyMetric
        {
            KAnonymityConfig = KAnonymityConfig
        },
        SourceTable = new BigQueryTable
        {
            ProjectId = tableProjectId,
            DatasetId = datasetId,
            TableId = tableId
        },
        Actions =
        {
            new Google.Cloud.Dlp.V2.Action
            {
                PubSub = new PublishToPubSub
                {
                    Topic = $"projects/{callingProjectId}/topics/{topicId}"
                }
            }
        }
    };

    var submittedJob = dlp.CreateDlpJob(
        new CreateDlpJobRequest
        {
            ParentAsProjectName = new ProjectName(callingProjectId),
            RiskJob = config
        });

    // Listen to pub/sub for the job
    var subscriptionName = new SubscriptionName(callingProjectId, subscriptionId);
    SubscriberClient subscriber = SubscriberClient.CreateAsync(
        subscriptionName).Result;

    // SimpleSubscriber runs your message handle function on multiple
    // threads to maximize throughput.
    var done = new ManualResetEventSlim(false);
    subscriber.StartAsync((PubsubMessage message, CancellationToken cancel) =>
    {
        if (message.Attributes["DlpJobName"] == submittedJob.Name)
        {
            Thread.Sleep(500); // Wait for DLP API results to become consistent
            done.Set();
            return Task.FromResult(SubscriberClient.Reply.Ack);
        }
        else
        {
            return Task.FromResult(SubscriberClient.Reply.Nack);
        }
    });

    done.Wait(TimeSpan.FromMinutes(10)); // 10 minute timeout; may not work for large jobs
    subscriber.StopAsync(CancellationToken.None).Wait();

    // Process results
    var resultJob = dlp.GetDlpJob(new GetDlpJobRequest
    {
        DlpJobName = DlpJobName.Parse(submittedJob.Name)
    });

    var result = resultJob.RiskDetails.KAnonymityResult;

    for (int bucketIdx = 0; bucketIdx < result.EquivalenceClassHistogramBuckets.Count; bucketIdx++)
    {
        var bucket = result.EquivalenceClassHistogramBuckets[bucketIdx];
        Console.WriteLine($"Bucket {bucketIdx}");
        Console.WriteLine($"  Bucket size range: [{bucket.EquivalenceClassSizeLowerBound}, {bucket.EquivalenceClassSizeUpperBound}].");
        Console.WriteLine($"  {bucket.BucketSize} unique value(s) total.");

        foreach (var bucketValue in bucket.BucketValues)
        {
            // 'UnpackValue(x)' is a prettier version of 'x.toString()'
            Console.WriteLine($"    Quasi-ID values: [{String.Join(',', bucketValue.QuasiIdsValues.Select(x => DlpSamplesUtils.UnpackValue(x)))}]");
            Console.WriteLine($"    Class size: {bucketValue.EquivalenceClassSize}");
        }
    }

    return 0;
}

Computing l-diversity with Cloud DLP

L-diversity is an extension of k-anonymity that additionally measures the diversity of sensitive values for each column in which they occur. A dataset has l-diversity if, for every set of rows with identical quasi-identifiers, there are at least l distinct values for each sensitive attribute.

You can compute the l-diversity value for one or more columns, or fields, by first following the instructions in the previous section, Risk analysis using Cloud DLP.

Within the LDiversityConfig object, you specify the following:

  • quasiIds[]: A set of quasi-identifiers (FieldId objects) that indicate how equivalence classes are defined for the l-diversity computation. As with KAnonymityConfig, when you specify multiple fields, they are considered a single composite key.
  • sensitiveAttribute: Sensitive field (FieldId object) for computing the l-diversity value.

Code examples

Following is sample code in several languages that demonstrates how to use Cloud DLP to compute a l-diversity value.

Java

/**
 * Calculate l-diversity for an attribute relative to quasi-identifiers in a BigQuery table.
 *
 * @param projectId The Google Cloud Platform project ID to run the API call under.
 * @param datasetId The BigQuery dataset to analyze.
 * @param tableId The BigQuery table to analyze.
 * @param sensitiveAttribute The name of the attribute to compare the quasi-ID against
 * @param quasiIds A set of column names that form a composite key ('quasi-identifiers').
 * @param topicId The name of the Pub/Sub topic to notify once the job completes
 * @param subscriptionId The name of the Pub/Sub subscription to use when listening for job
 *     completion status.
 */
private static void calculateLDiversity(
    String projectId,
    String datasetId,
    String tableId,
    String sensitiveAttribute,
    List<String> quasiIds,
    String topicId,
    String subscriptionId)
    throws Exception {

  // Instantiates a client
  try (DlpServiceClient dlpServiceClient = DlpServiceClient.create()) {

    FieldId sensitiveAttributeField = FieldId.newBuilder().setName(sensitiveAttribute).build();

    List<FieldId> quasiIdFields =
        quasiIds
            .stream()
            .map(columnName -> FieldId.newBuilder().setName(columnName).build())
            .collect(Collectors.toList());

    LDiversityConfig ldiversityConfig =
        LDiversityConfig.newBuilder()
            .addAllQuasiIds(quasiIdFields)
            .setSensitiveAttribute(sensitiveAttributeField)
            .build();

    BigQueryTable bigQueryTable =
        BigQueryTable.newBuilder()
            .setProjectId(projectId)
            .setDatasetId(datasetId)
            .setTableId(tableId)
            .build();

    PrivacyMetric privacyMetric =
        PrivacyMetric.newBuilder().setLDiversityConfig(ldiversityConfig).build();

    String topicName = String.format("projects/%s/topics/%s", projectId, topicId);

    PublishToPubSub publishToPubSub = PublishToPubSub.newBuilder().setTopic(topicName).build();

    // Create action to publish job status notifications over Google Cloud Pub/Sub
    Action action = Action.newBuilder().setPubSub(publishToPubSub).build();

    RiskAnalysisJobConfig riskAnalysisJobConfig =
        RiskAnalysisJobConfig.newBuilder()
            .setSourceTable(bigQueryTable)
            .setPrivacyMetric(privacyMetric)
            .addActions(action)
            .build();

    CreateDlpJobRequest createDlpJobRequest =
        CreateDlpJobRequest.newBuilder()
            .setParent(ProjectName.of(projectId).toString())
            .setRiskJob(riskAnalysisJobConfig)
            .build();

    DlpJob dlpJob = dlpServiceClient.createDlpJob(createDlpJobRequest);
    String dlpJobName = dlpJob.getName();

    final SettableApiFuture<Boolean> done = SettableApiFuture.create();

    // Set up a Pub/Sub subscriber to listen on the job completion status
    Subscriber subscriber =
        Subscriber.newBuilder(
                ProjectSubscriptionName.newBuilder()
                    .setProject(projectId)
                    .setSubscription(subscriptionId)
                    .build(),
          (pubsubMessage, ackReplyConsumer) -> {
            if (pubsubMessage.getAttributesCount() > 0
                && pubsubMessage.getAttributesMap().get("DlpJobName").equals(dlpJobName)) {
              // notify job completion
              done.set(true);
              ackReplyConsumer.ack();
            }
          })
            .build();
    subscriber.startAsync();

    // Wait for job completion semi-synchronously
    // For long jobs, consider using a truly asynchronous execution model such as Cloud Functions
    try {
      done.get(1, TimeUnit.MINUTES);
      Thread.sleep(500); // Wait for the job to become available
    } catch (TimeoutException e) {
      System.out.println("Unable to verify job completion.");
    }

    // retrieve completed job status
    DlpJob completedJob =
        dlpServiceClient.getDlpJob(GetDlpJobRequest.newBuilder().setName(dlpJobName).build());

    System.out.println("Job status: " + completedJob.getState());
    AnalyzeDataSourceRiskDetails riskDetails = completedJob.getRiskDetails();

    LDiversityResult ldiversityResult = riskDetails.getLDiversityResult();
    for (LDiversityHistogramBucket result :
        ldiversityResult.getSensitiveValueFrequencyHistogramBucketsList()) {
      for (LDiversityEquivalenceClass bucket : result.getBucketValuesList()) {
        List<String> quasiIdValues =
            bucket
                .getQuasiIdsValuesList()
                .stream()
                .map(Value::toString)
                .collect(Collectors.toList());

        System.out.println("\tQuasi-ID values: " + String.join(", ", quasiIdValues));
        System.out.println("\tClass size: " + bucket.getEquivalenceClassSize());

        for (ValueFrequency valueFrequency : bucket.getTopSensitiveValuesList()) {
          System.out.printf(
              "\t\tSensitive value %s occurs %d time(s).\n",
              valueFrequency.getValue().toString(), valueFrequency.getCount());
        }
      }
    }
  } catch (Exception e) {
    System.out.println("Error in calculateLDiversity: " + e.getMessage());
  }
}

Node.js

// Import the Google Cloud client libraries
const DLP = require('@google-cloud/dlp');
const {PubSub} = require('@google-cloud/pubsub');

// Instantiates clients
const dlp = new DLP.DlpServiceClient();
const pubsub = new PubSub();

// The project ID to run the API call under
// const callingProjectId = process.env.GCLOUD_PROJECT;

// The project ID the table is stored under
// This may or (for public datasets) may not equal the calling project ID
// const tableProjectId = process.env.GCLOUD_PROJECT;

// The ID of the dataset to inspect, e.g. 'my_dataset'
// const datasetId = 'my_dataset';

// The ID of the table to inspect, e.g. 'my_table'
// const tableId = 'my_table';

// The name of the Pub/Sub topic to notify once the job completes
// TODO(developer): create a Pub/Sub topic to use for this
// const topicId = 'MY-PUBSUB-TOPIC'

// The name of the Pub/Sub subscription to use when listening for job
// completion notifications
// TODO(developer): create a Pub/Sub subscription to use for this
// const subscriptionId = 'MY-PUBSUB-SUBSCRIPTION'

// The column to measure l-diversity relative to, e.g. 'firstName'
// const sensitiveAttribute = 'name';

// A set of columns that form a composite key ('quasi-identifiers')
// const quasiIds = [{ name: 'age' }, { name: 'city' }];

const sourceTable = {
  projectId: tableProjectId,
  datasetId: datasetId,
  tableId: tableId,
};

// Construct request for creating a risk analysis job
const request = {
  parent: dlp.projectPath(callingProjectId),
  riskJob: {
    privacyMetric: {
      lDiversityConfig: {
        quasiIds: quasiIds,
        sensitiveAttribute: {
          name: sensitiveAttribute,
        },
      },
    },
    sourceTable: sourceTable,
    actions: [
      {
        pubSub: {
          topic: `projects/${callingProjectId}/topics/${topicId}`,
        },
      },
    ],
  },
};

// Create helper function for unpacking values
const getValue = obj => obj[Object.keys(obj)[0]];

try {
  // Run risk analysis job
  const [topicResponse] = await pubsub.topic(topicId).get();
  const subscription = await topicResponse.subscription(subscriptionId);
  const [jobsResponse] = await dlp.createDlpJob(request);
  const jobName = jobsResponse.name;
  // Watch the Pub/Sub topic until the DLP job finishes
  await new Promise((resolve, reject) => {
    const messageHandler = message => {
      if (message.attributes && message.attributes.DlpJobName === jobName) {
        message.ack();
        subscription.removeListener('message', messageHandler);
        subscription.removeListener('error', errorHandler);
        resolve(jobName);
      } else {
        message.nack();
      }
    };

    const errorHandler = err => {
      subscription.removeListener('message', messageHandler);
      subscription.removeListener('error', errorHandler);
      reject(err);
    };

    subscription.on('message', messageHandler);
    subscription.on('error', errorHandler);
  });
  setTimeout(() => {
    console.log(` Waiting for DLP job to fully complete`);
  }, 500);
  const [job] = await dlp.getDlpJob({name: jobName});
  const histogramBuckets =
    job.riskDetails.lDiversityResult.sensitiveValueFrequencyHistogramBuckets;

  histogramBuckets.forEach((histogramBucket, histogramBucketIdx) => {
    console.log(`Bucket ${histogramBucketIdx}:`);

    console.log(
      `Bucket size range: [${
        histogramBucket.sensitiveValueFrequencyLowerBound
      }, ${histogramBucket.sensitiveValueFrequencyUpperBound}]`
    );
    histogramBucket.bucketValues.forEach(valueBucket => {
      const quasiIdValues = valueBucket.quasiIdsValues
        .map(getValue)
        .join(', ');
      console.log(`  Quasi-ID values: {${quasiIdValues}}`);
      console.log(`  Class size: ${valueBucket.equivalenceClassSize}`);
      valueBucket.topSensitiveValues.forEach(valueObj => {
        console.log(
          `    Sensitive value ${getValue(valueObj.value)} occurs ${
            valueObj.count
          } time(s).`
        );
      });
    });
  });
} catch (err) {
  console.log(`Error in lDiversityAnalysis: ${err.message || err}`);
}

Python

def l_diversity_analysis(project, table_project_id, dataset_id, table_id,
                         topic_id, subscription_id, sensitive_attribute,
                         quasi_ids, timeout=300):
    """Uses the Data Loss Prevention API to compute the l-diversity of a
        column set in a Google BigQuery table.
    Args:
        project: The Google Cloud project id to use as a parent resource.
        table_project_id: The Google Cloud project id where the BigQuery table
            is stored.
        dataset_id: The id of the dataset to inspect.
        table_id: The id of the table to inspect.
        topic_id: The name of the Pub/Sub topic to notify once the job
            completes.
        subscription_id: The name of the Pub/Sub subscription to use when
            listening for job completion notifications.
        sensitive_attribute: The column to measure l-diversity relative to.
        quasi_ids: A set of columns that form a composite key.
        timeout: The number of seconds to wait for a response from the API.

    Returns:
        None; the response from the API is printed to the terminal.
    """

    # Import the client library.
    import google.cloud.dlp

    # This sample additionally uses Cloud Pub/Sub to receive results from
    # potentially long-running operations.
    import google.cloud.pubsub

    # Create helper function for unpacking values
    def get_values(obj):
        return int(obj.integer_value)

    def callback(message):
        if (message.attributes['DlpJobName'] == operation.name):
            # This is the message we're looking for, so acknowledge it.
            message.ack()

            # Now that the job is done, fetch the results and print them.
            job = dlp.get_dlp_job(operation.name)
            histogram_buckets = (
                job.risk_details
                   .l_diversity_result
                   .sensitive_value_frequency_histogram_buckets)
            # Print bucket stats
            for i, bucket in enumerate(histogram_buckets):
                print('Bucket {}:'.format(i))
                print('   Bucket size range: [{}, {}]'.format(
                    bucket.sensitive_value_frequency_lower_bound,
                    bucket.sensitive_value_frequency_upper_bound))
                for value_bucket in bucket.bucket_values:
                    print('   Quasi-ID values: {}'.format(
                        map(get_values, value_bucket.quasi_ids_values)))
                    print('   Class size: {}'.format(
                        value_bucket.equivalence_class_size))
                    for value in value_bucket.top_sensitive_values:
                        print(('   Sensitive value {} occurs {} time(s)'
                               .format(value.value, value.count)))
            subscription.set_result(None)
        else:
            # This is not the message we're looking for.
            message.drop()

    # Instantiate a client.
    dlp = google.cloud.dlp.DlpServiceClient()

    # Convert the project id into a full resource id.
    parent = dlp.project_path(project)

    # Location info of the BigQuery table.
    source_table = {
        'project_id': table_project_id,
        'dataset_id': dataset_id,
        'table_id': table_id
    }

    # Convert quasi id list to Protobuf type
    def map_fields(field):
        return {'name': field}

    quasi_ids = map(map_fields, quasi_ids)

    # Tell the API where to send a notification when the job is complete.
    actions = [{
        'pub_sub': {'topic': '{}/topics/{}'.format(parent, topic_id)}
    }]

    # Configure risk analysis job
    # Give the name of the numeric column to compute risk metrics for
    risk_job = {
        'privacy_metric': {
            'l_diversity_config': {
                'quasi_ids': quasi_ids,
                'sensitive_attribute': {
                    'name': sensitive_attribute
                }
            }
        },
        'source_table': source_table,
        'actions': actions
    }

    # Create a Pub/Sub client and find the subscription. The subscription is
    # expected to already be listening to the topic.
    subscriber = google.cloud.pubsub.SubscriberClient()
    subscription_path = subscriber.subscription_path(
        project, subscription_id)
    subscription = subscriber.subscribe(subscription_path, callback)

    # Call API to start risk analysis job
    operation = dlp.create_dlp_job(parent, risk_job=risk_job)

    try:
        subscription.result(timeout=timeout)
    except TimeoutError:
        print('No event received before the timeout. Please verify that the '
              'subscription provided is subscribed to the topic provided.')
        subscription.close()

Go

// riskLDiversity computes the L Diversity of the given columns.
func riskLDiversity(w io.Writer, client *dlp.Client, project, dataProject, pubSubTopic, pubSubSub, datasetID, tableID, sensitiveAttribute string, columnNames ...string) {
	ctx := context.Background()

	// Create a PubSub Client used to listen for when the inspect job finishes.
	pClient, err := pubsub.NewClient(ctx, project)
	if err != nil {
		log.Fatalf("Error creating PubSub client: %v", err)
	}
	defer pClient.Close()

	// Create a PubSub subscription we can use to listen for messages.
	s, err := setupPubSub(ctx, pClient, project, pubSubTopic, pubSubSub)
	if err != nil {
		log.Fatalf("Error setting up PubSub: %v\n", err)
	}

	// topic is the PubSub topic string where messages should be sent.
	topic := "projects/" + project + "/topics/" + pubSubTopic

	// Build the QuasiID slice.
	var q []*dlppb.FieldId
	for _, c := range columnNames {
		q = append(q, &dlppb.FieldId{Name: c})
	}

	// Create a configured request.
	req := &dlppb.CreateDlpJobRequest{
		Parent: "projects/" + project,
		Job: &dlppb.CreateDlpJobRequest_RiskJob{
			RiskJob: &dlppb.RiskAnalysisJobConfig{
				// PrivacyMetric configures what to compute.
				PrivacyMetric: &dlppb.PrivacyMetric{
					Type: &dlppb.PrivacyMetric_LDiversityConfig_{
						LDiversityConfig: &dlppb.PrivacyMetric_LDiversityConfig{
							QuasiIds: q,
							SensitiveAttribute: &dlppb.FieldId{
								Name: sensitiveAttribute,
							},
						},
					},
				},
				// SourceTable describes where to find the data.
				SourceTable: &dlppb.BigQueryTable{
					ProjectId: dataProject,
					DatasetId: datasetID,
					TableId:   tableID,
				},
				// Send a message to PubSub using Actions.
				Actions: []*dlppb.Action{
					{
						Action: &dlppb.Action_PubSub{
							PubSub: &dlppb.Action_PublishToPubSub{
								Topic: topic,
							},
						},
					},
				},
			},
		},
	}
	// Create the risk job.
	j, err := client.CreateDlpJob(context.Background(), req)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Fprintf(w, "Created job: %v\n", j.GetName())

	// Wait for the risk job to finish by waiting for a PubSub message.
	ctx, cancel := context.WithCancel(ctx)
	err = s.Receive(ctx, func(ctx context.Context, msg *pubsub.Message) {
		// If this is the wrong job, do not process the result.
		if msg.Attributes["DlpJobName"] != j.GetName() {
			msg.Nack()
			return
		}
		msg.Ack()
		time.Sleep(500 * time.Millisecond)
		j, err := client.GetDlpJob(ctx, &dlppb.GetDlpJobRequest{
			Name: j.GetName(),
		})
		if err != nil {
			log.Fatalf("Error getting completed job: %v\n", err)
		}
		h := j.GetRiskDetails().GetLDiversityResult().GetSensitiveValueFrequencyHistogramBuckets()
		for i, b := range h {
			fmt.Fprintf(w, "Histogram bucket %v\n", i)
			fmt.Fprintf(w, "  Size range: [%v,%v]\n", b.GetSensitiveValueFrequencyLowerBound(), b.GetSensitiveValueFrequencyUpperBound())
			fmt.Fprintf(w, "  %v unique values total\n", b.GetBucketSize())
			for _, v := range b.GetBucketValues() {
				var qvs []string
				for _, qv := range v.GetQuasiIdsValues() {
					qvs = append(qvs, qv.String())
				}
				fmt.Fprintf(w, "    QuasiID values: %s\n", strings.Join(qvs, ", "))
				fmt.Fprintf(w, "    Class size: %v\n", v.GetEquivalenceClassSize())
				for _, sv := range v.GetTopSensitiveValues() {
					fmt.Fprintf(w, "    Sensitive value %v occurs %v times\n", sv.GetValue(), sv.GetCount())
				}
			}
		}
		// Stop listening for more messages.
		cancel()
	})
	if err != nil {
		log.Fatalf("Error receiving from PubSub: %v\n", err)
	}
}

PHP

/**
 * Computes the l-diversity of a column set in a Google BigQuery table.
 */
use Google\Cloud\Core\ExponentialBackoff;
use Google\Cloud\Dlp\V2\DlpServiceClient;
use Google\Cloud\Dlp\V2\RiskAnalysisJobConfig;
use Google\Cloud\Dlp\V2\BigQueryTable;
use Google\Cloud\Dlp\V2\DlpJob\JobState;
use Google\Cloud\Dlp\V2\Action;
use Google\Cloud\Dlp\V2\Action\PublishToPubSub;
use Google\Cloud\Dlp\V2\PrivacyMetric\LDiversityConfig;
use Google\Cloud\Dlp\V2\PrivacyMetric;
use Google\Cloud\Dlp\V2\FieldId;
use Google\Cloud\PubSub\PubSubClient;

/** Uncomment and populate these variables in your code */
// $callingProjectId = 'The project ID to run the API call under';
// $dataProjectId = 'The project ID containing the target Datastore';
// $topicId = 'The name of the Pub/Sub topic to notify once the job completes';
// $subscriptionId = 'The name of the Pub/Sub subscription to use when listening for job';
// $datasetId = 'The ID of the dataset to inspect';
// $tableId = 'The ID of the table to inspect';
// $sensitiveAttribute = 'The column to measure l-diversity relative to, e.g. "firstName"';
// $quasiIdNames = ['array columns that form a composite key (quasi-identifiers)'];

// Instantiate a client.
$dlp = new DlpServiceClient([
    'projectId' => $callingProjectId,
]);
$pubsub = new PubSubClient([
    'projectId' => $callingProjectId,
]);
$topic = $pubsub->topic($topicId);

// Construct risk analysis config
$quasiIds = array_map(
    function ($id) {
        return (new FieldId())->setName($id);
    },
    $quasiIdNames
);

$sensitiveField = (new FieldId())
    ->setName($sensitiveAttribute);

$statsConfig = (new LDiversityConfig())
    ->setQuasiIds($quasiIds)
    ->setSensitiveAttribute($sensitiveField);

$privacyMetric = (new PrivacyMetric())
    ->setLDiversityConfig($statsConfig);

// Construct items to be analyzed
$bigqueryTable = (new BigQueryTable())
    ->setProjectId($dataProjectId)
    ->setDatasetId($datasetId)
    ->setTableId($tableId);

// Construct the action to run when job completes
$pubSubAction = (new PublishToPubSub())
    ->setTopic($topic->name());

$action = (new Action())
    ->setPubSub($pubSubAction);

// Construct risk analysis job config to run
$riskJob = (new RiskAnalysisJobConfig())
    ->setPrivacyMetric($privacyMetric)
    ->setSourceTable($bigqueryTable)
    ->setActions([$action]);

// Listen for job notifications via an existing topic/subscription.
$subscription = $topic->subscription($subscriptionId);

// Submit request
$parent = $dlp->projectName($callingProjectId);
$job = $dlp->createDlpJob($parent, [
    'riskJob' => $riskJob
]);

// Poll Pub/Sub using exponential backoff until job finishes
$backoff = new ExponentialBackoff(20);
$backoff->execute(function () use ($subscription, $dlp, &$job) {
    printf('Waiting for job to complete' . PHP_EOL);
    foreach ($subscription->pull() as $message) {
        if (isset($message->attributes()['DlpJobName']) &&
            $message->attributes()['DlpJobName'] === $job->getName()) {
            $subscription->acknowledge($message);
            // Get the updated job. Loop to avoid race condition with DLP API.
            do {
                $job = $dlp->getDlpJob($job->getName());
            } while ($job->getState() == JobState::RUNNING);
            return true;
        }
    }
    throw new Exception('Job has not yet completed');
});

// Print finding counts
printf('Job %s status: %s' . PHP_EOL, $job->getName(), JobState::name($job->getState()));
switch ($job->getState()) {
    case JobState::DONE:
        $histBuckets = $job->getRiskDetails()->getLDiversityResult()->getSensitiveValueFrequencyHistogramBuckets();

        foreach ($histBuckets as $bucketIndex => $histBucket) {
            // Print bucket stats
            printf('Bucket %s:' . PHP_EOL, $bucketIndex);
            printf(
                '  Bucket size range: [%s, %s]' . PHP_EOL,
                $histBucket->getSensitiveValueFrequencyLowerBound(),
                $histBucket->getSensitiveValueFrequencyUpperBound()
            );

            // Print bucket values
            foreach ($histBucket->getBucketValues() as $percent => $valueBucket) {
                printf(
                    '  Class size: %s' . PHP_EOL,
                    $valueBucket->getEquivalenceClassSize()
                );

                // Pretty-print quasi-ID values
                print('  Quasi-ID values:' . PHP_EOL);
                foreach ($valueBucket->getQuasiIdsValues() as $index => $value) {
                    print('    ' . $value->serializeToJsonString() . PHP_EOL);
                }

                // Pretty-print sensitive values
                $topValues = $valueBucket->getTopSensitiveValues();
                foreach ($topValues as $topValue) {
                    printf(
                        '  Sensitive value %s occurs %s time(s).' . PHP_EOL,
                        $topValue->getValue()->serializeToJsonString(),
                        $topValue->getCount()
                    );
                }
            }
        }
        break;
    case JobState::FAILED:
        printf('Job %s had errors:' . PHP_EOL, $job->getName());
        $errors = $job->getErrors();
        foreach ($errors as $error) {
            var_dump($error->getDetails());
        }
        break;
    default:
        printf('Unexpected job state. Most likely, the job is either running or has not yet started.');
}

C#

public static object LDiversity(
    string callingProjectId,
    string tableProjectId,
    string datasetId,
    string tableId,
    string topicId,
    string subscriptionId,
    IEnumerable<FieldId> quasiIds,
    string sensitiveAttribute)
{
    DlpServiceClient dlp = DlpServiceClient.Create();

    // Construct + submit the job
    var ldiversityConfig = new LDiversityConfig
    {
        SensitiveAttribute = new FieldId { Name = sensitiveAttribute },
        QuasiIds = { quasiIds }
    };

    var config = new RiskAnalysisJobConfig
    {
        PrivacyMetric = new PrivacyMetric
        {
            LDiversityConfig = ldiversityConfig
        },
        SourceTable = new BigQueryTable
        {
            ProjectId = tableProjectId,
            DatasetId = datasetId,
            TableId = tableId
        },
        Actions = {
            new Google.Cloud.Dlp.V2.Action
            {
                PubSub = new PublishToPubSub
                {
                    Topic = $"projects/{callingProjectId}/topics/{topicId}"
                }
            }
        }
    };

    var submittedJob = dlp.CreateDlpJob(
        new CreateDlpJobRequest
        {
            ParentAsProjectName = new ProjectName(callingProjectId),
            RiskJob = config
        });

    // Listen to pub/sub for the job
    var subscriptionName = new SubscriptionName(callingProjectId, subscriptionId);
    SubscriberClient subscriber = SubscriberClient.CreateAsync(
        subscriptionName).Result;

    // SimpleSubscriber runs your message handle function on multiple
    // threads to maximize throughput.
    var done = new ManualResetEventSlim(false);
    subscriber.StartAsync((PubsubMessage message, CancellationToken cancel) =>
    {
        if (message.Attributes["DlpJobName"] == submittedJob.Name)
        {
            Thread.Sleep(500); // Wait for DLP API results to become consistent
            done.Set();
            return Task.FromResult(SubscriberClient.Reply.Ack);
        }
        else
        {
            return Task.FromResult(SubscriberClient.Reply.Nack);
        }
    });

    done.Wait(TimeSpan.FromMinutes(10)); // 10 minute timeout; may not work for large jobs
    subscriber.StopAsync(CancellationToken.None).Wait();

    // Process results
    var resultJob = dlp.GetDlpJob(
        new GetDlpJobRequest
        {
            DlpJobName = DlpJobName.Parse(submittedJob.Name)
        });

    var result = resultJob.RiskDetails.LDiversityResult;

    for (int bucketIdx = 0; bucketIdx < result.SensitiveValueFrequencyHistogramBuckets.Count; bucketIdx++)
    {
        var bucket = result.SensitiveValueFrequencyHistogramBuckets[bucketIdx];
        Console.WriteLine($"Bucket {bucketIdx}");
        Console.WriteLine($"  Bucket size range: [{bucket.SensitiveValueFrequencyLowerBound}, {bucket.SensitiveValueFrequencyUpperBound}].");
        Console.WriteLine($"  {bucket.BucketSize} unique value(s) total.");

        foreach (var bucketValue in bucket.BucketValues)
        {
            // 'UnpackValue(x)' is a prettier version of 'x.toString()'
            Console.WriteLine($"    Quasi-ID values: [{String.Join(',', bucketValue.QuasiIdsValues.Select(x => DlpSamplesUtils.UnpackValue(x)))}]");
            Console.WriteLine($"    Class size: {bucketValue.EquivalenceClassSize}");

            foreach (var topValue in bucketValue.TopSensitiveValues)
            {
                Console.WriteLine($"    Sensitive value {DlpSamplesUtils.UnpackValue(topValue.Value)} occurs {topValue.Count} time(s).");
            }
        }
    }

    return 0;
}

Computing k-map estimates with Cloud DLP

You can estimate k-map values using Cloud DLP, which uses a statistical model to estimate a re-identification dataset. This is in contrast to the other risk analysis methods, in which the attack dataset is explicitly known. Depending on the type of data, Cloud DLP uses publicly available datasets (for example, from the US Census) or a custom statistical model (for example, one or more BigQuery tables that you specify), or it extrapolates from the distribution of values in your input dataset.

To compute a k-map estimate using Cloud DLP, first follow the instructions in the previous section, Risk analysis using Cloud DLP.

Within the KMapEstimationConfig object, you specify the following:

  • quasiIds[]: Required. Fields (TaggedField objects) considered to be quasi-identifiers to scan and use to compute k-map. No two columns can have the same tag. These can be any of the following:

    • An infoType: This causes Cloud DLP to use the relevant public dataset as a statistical model of population, including US ZIP codes, region codes, ages, and genders.
    • A custom infoType: A custom tag wherein you indicate an auxiliary table (an AuxiliaryTable object) that contains statistical information about the possible values of this column.
    • The inferred tag: If no semantic tag is indicated, specify inferred. Cloud DLP infers the statistical model from the distribution of values in the input data.
  • regionCode: An ISO 3166-1 alpha-2 region code for Cloud DLP to use in statistical modeling. This value is required if no column is tagged with a region-specific infoType (for example, a US ZIP code) or a region code.

  • auxiliaryTables[]: Auxiliary tables (AuxiliaryTable objects) to use in the analysis. Each custom tag used to tag a quasi-identifier column (from quasiIds[]) must appear in exactly one column of one auxiliary table.

Code examples

Following is sample code in several languages that demonstrates how to use Cloud DLP to compute a k-map value.

Java

/**
 * Calculate k-map risk estimation for an attribute relative to quasi-identifiers in a BigQuery
 * table.
 *
 * @param projectId The Google Cloud Platform project ID to run the API call under.
 * @param datasetId The BigQuery dataset to analyze.
 * @param tableId The BigQuery table to analyze.
 * @param quasiIds A set of column names that form a composite key ('quasi-identifiers').
 * @param infoTypes The infoTypes corresponding to each quasi-id column
 * @param regionCode An ISO-3166-1 region code specifying the k-map distribution region
 * @param topicId The name of the Pub/Sub topic to notify once the job completes
 * @param subscriptionId The name of the Pub/Sub subscription to use when listening for job
 *     completion status.
 */
private static void calculateKMap(
    String projectId,
    String datasetId,
    String tableId,
    List<String> quasiIds,
    List<InfoType> infoTypes,
    String regionCode,
    String topicId,
    String subscriptionId)
    throws Exception {

  // Instantiates a client
  try (DlpServiceClient dlpServiceClient = DlpServiceClient.create()) {

    Iterator<String> quasiIdsIterator = quasiIds.iterator();
    Iterator<InfoType> infoTypesIterator = infoTypes.iterator();

    if (quasiIds.size() != infoTypes.size()) {
      throw new IllegalArgumentException("The numbers of quasi-IDs and infoTypes must be equal!");
    }

    ArrayList<TaggedField> taggedFields = new ArrayList();

    while (quasiIdsIterator.hasNext() || infoTypesIterator.hasNext()) {
      taggedFields.add(
          TaggedField.newBuilder()
              .setField(FieldId.newBuilder().setName(quasiIdsIterator.next()).build())
              .setInfoType(infoTypesIterator.next())
              .build());
    }

    KMapEstimationConfig kmapConfig =
        KMapEstimationConfig.newBuilder()
            .addAllQuasiIds(taggedFields)
            .setRegionCode(regionCode)
            .build();

    BigQueryTable bigQueryTable =
        BigQueryTable.newBuilder()
            .setProjectId(projectId)
            .setDatasetId(datasetId)
            .setTableId(tableId)
            .build();

    PrivacyMetric privacyMetric =
        PrivacyMetric.newBuilder().setKMapEstimationConfig(kmapConfig).build();

    String topicName = String.format("projects/%s/topics/%s", projectId, topicId);

    PublishToPubSub publishToPubSub = PublishToPubSub.newBuilder().setTopic(topicName).build();

    // Create action to publish job status notifications over Google Cloud Pub/Sub
    Action action = Action.newBuilder().setPubSub(publishToPubSub).build();

    RiskAnalysisJobConfig riskAnalysisJobConfig =
        RiskAnalysisJobConfig.newBuilder()
            .setSourceTable(bigQueryTable)
            .setPrivacyMetric(privacyMetric)
            .addActions(action)
            .build();

    CreateDlpJobRequest createDlpJobRequest =
        CreateDlpJobRequest.newBuilder()
            .setParent(ProjectName.of(projectId).toString())
            .setRiskJob(riskAnalysisJobConfig)
            .build();

    DlpJob dlpJob = dlpServiceClient.createDlpJob(createDlpJobRequest);
    String dlpJobName = dlpJob.getName();

    final SettableApiFuture<Boolean> done = SettableApiFuture.create();

    // Set up a Pub/Sub subscriber to listen on the job completion status
    Subscriber subscriber =
        Subscriber.newBuilder(
                ProjectSubscriptionName.newBuilder()
                    .setProject(projectId)
                    .setSubscription(subscriptionId)
                    .build(),
          (pubsubMessage, ackReplyConsumer) -> {
            if (pubsubMessage.getAttributesCount() > 0
                && pubsubMessage.getAttributesMap().get("DlpJobName").equals(dlpJobName)) {
              // notify job completion
              done.set(true);
              ackReplyConsumer.ack();
            }
          })
            .build();
    subscriber.startAsync();

    // Wait for job completion semi-synchronously
    // For long jobs, consider using a truly asynchronous execution model such as Cloud Functions
    try {
      done.get(1, TimeUnit.MINUTES);
      Thread.sleep(500); // Wait for the job to become available
    } catch (TimeoutException e) {
      System.out.println("Unable to verify job completion.");
    }

    // retrieve completed job status
    DlpJob completedJob =
        dlpServiceClient.getDlpJob(GetDlpJobRequest.newBuilder().setName(dlpJobName).build());

    System.out.println("Job status: " + completedJob.getState());
    AnalyzeDataSourceRiskDetails riskDetails = completedJob.getRiskDetails();

    KMapEstimationResult kmapResult = riskDetails.getKMapEstimationResult();
    for (KMapEstimationHistogramBucket result : kmapResult.getKMapEstimationHistogramList()) {

      System.out.printf(
          "\tAnonymity range: [%d, %d]\n", result.getMinAnonymity(), result.getMaxAnonymity());
      System.out.printf("\tSize: %d\n", result.getBucketSize());

      for (KMapEstimationQuasiIdValues valueBucket : result.getBucketValuesList()) {
        String quasiIdValues =
            valueBucket
                .getQuasiIdsValuesList()
                .stream()
                .map(
                    v -> {
                      String s = v.toString();
                      return s.substring(s.indexOf(':') + 1).trim();
                    })
                .collect(Collectors.joining(", "));

        System.out.printf("\tValues: {%s}\n", quasiIdValues);
        System.out.printf(
            "\tEstimated k-map anonymity: %d\n", valueBucket.getEstimatedAnonymity());
      }
    }
  } catch (Exception e) {
    System.out.println("Error in calculateKMap: " + e.getMessage());
  }
}

Node.js

// Import the Google Cloud client libraries
const DLP = require('@google-cloud/dlp');
const {PubSub} = require('@google-cloud/pubsub');

// Instantiates clients
const dlp = new DLP.DlpServiceClient();
const pubsub = new PubSub();

// The project ID to run the API call under
// const callingProjectId = process.env.GCLOUD_PROJECT;

// The project ID the table is stored under
// This may or (for public datasets) may not equal the calling project ID
// const tableProjectId = process.env.GCLOUD_PROJECT;

// The ID of the dataset to inspect, e.g. 'my_dataset'
// const datasetId = 'my_dataset';

// The ID of the table to inspect, e.g. 'my_table'
// const tableId = 'my_table';

// The name of the Pub/Sub topic to notify once the job completes
// TODO(developer): create a Pub/Sub topic to use for this
// const topicId = 'MY-PUBSUB-TOPIC'

// The name of the Pub/Sub subscription to use when listening for job
// completion notifications
// TODO(developer): create a Pub/Sub subscription to use for this
// const subscriptionId = 'MY-PUBSUB-SUBSCRIPTION'

// The ISO 3166-1 region code that the data is representative of
// Can be omitted if using a region-specific infoType (such as US_ZIP_5)
// const regionCode = 'USA';

// A set of columns that form a composite key ('quasi-identifiers'), and
// optionally their reidentification distributions
// const quasiIds = [{ field: { name: 'age' }, infoType: { name: 'AGE' }}];

const sourceTable = {
  projectId: tableProjectId,
  datasetId: datasetId,
  tableId: tableId,
};

// Construct request for creating a risk analysis job
const request = {
  parent: dlp.projectPath(process.env.GCLOUD_PROJECT),
  riskJob: {
    privacyMetric: {
      kMapEstimationConfig: {
        quasiIds: quasiIds,
        regionCode: regionCode,
      },
    },
    sourceTable: sourceTable,
    actions: [
      {
        pubSub: {
          topic: `projects/${callingProjectId}/topics/${topicId}`,
        },
      },
    ],
  },
};

// Create helper function for unpacking values
const getValue = obj => obj[Object.keys(obj)[0]];

try {
  // Run risk analysis job
  const [topicResponse] = await pubsub.topic(topicId).get();
  const subscription = await topicResponse.subscription(subscriptionId);
  const [jobsResponse] = await dlp.createDlpJob(request);
  const jobName = jobsResponse.name;
  // Watch the Pub/Sub topic until the DLP job finishes
  await new Promise((resolve, reject) => {
    const messageHandler = message => {
      if (message.attributes && message.attributes.DlpJobName === jobName) {
        message.ack();
        subscription.removeListener('message', messageHandler);
        subscription.removeListener('error', errorHandler);
        resolve(jobName);
      } else {
        message.nack();
      }
    };

    const errorHandler = err => {
      subscription.removeListener('message', messageHandler);
      subscription.removeListener('error', errorHandler);
      reject(err);
    };

    subscription.on('message', messageHandler);
    subscription.on('error', errorHandler);
  });
  setTimeout(() => {
    console.log(` Waiting for DLP job to fully complete`);
  }, 500);
  const [job] = await dlp.getDlpJob({name: jobName});
  const histogramBuckets =
    job.riskDetails.kMapEstimationResult.kMapEstimationHistogram;

  histogramBuckets.forEach((histogramBucket, histogramBucketIdx) => {
    console.log(`Bucket ${histogramBucketIdx}:`);
    console.log(
      `  Anonymity range: [${histogramBucket.minAnonymity}, ${
        histogramBucket.maxAnonymity
      }]`
    );
    console.log(`  Size: ${histogramBucket.bucketSize}`);
    histogramBucket.bucketValues.forEach(valueBucket => {
      const values = valueBucket.quasiIdsValues.map(value => getValue(value));
      console.log(`    Values: ${values.join(' ')}`);
      console.log(
        `    Estimated k-map anonymity: ${valueBucket.estimatedAnonymity}`
      );
    });
  });
} catch (err) {
  console.log(`Error in kMapEstimationAnalysis: ${err.message || err}`);
}

Python

def k_map_estimate_analysis(project, table_project_id, dataset_id, table_id,
                            topic_id, subscription_id, quasi_ids, info_types,
                            region_code='US', timeout=300):
    """Uses the Data Loss Prevention API to compute the k-map risk estimation
        of a column set in a Google BigQuery table.
    Args:
        project: The Google Cloud project id to use as a parent resource.
        table_project_id: The Google Cloud project id where the BigQuery table
            is stored.
        dataset_id: The id of the dataset to inspect.
        table_id: The id of the table to inspect.
        column_name: The name of the column to compute risk metrics for.
        topic_id: The name of the Pub/Sub topic to notify once the job
            completes.
        subscription_id: The name of the Pub/Sub subscription to use when
            listening for job completion notifications.
        quasi_ids: A set of columns that form a composite key and optionally
            their reidentification distributions.
        info_types: Type of information of the quasi_id in order to provide a
            statistical model of population.
        region_code: The ISO 3166-1 region code that the data is representative
            of. Can be omitted if using a region-specific infoType (such as
            US_ZIP_5)
        timeout: The number of seconds to wait for a response from the API.

    Returns:
        None; the response from the API is printed to the terminal.
    """

    # Import the client library.
    import google.cloud.dlp

    # This sample additionally uses Cloud Pub/Sub to receive results from
    # potentially long-running operations.
    import google.cloud.pubsub

    # Create helper function for unpacking values
    def get_values(obj):
        return int(obj.integer_value)

    def callback(message):
        if (message.attributes['DlpJobName'] == operation.name):
            # This is the message we're looking for, so acknowledge it.
            message.ack()

            # Now that the job is done, fetch the results and print them.
            job = dlp.get_dlp_job(operation.name)
            histogram_buckets = (job.risk_details
                                    .k_map_estimation_result
                                    .k_map_estimation_histogram)
            # Print bucket stats
            for i, bucket in enumerate(histogram_buckets):
                print('Bucket {}:'.format(i))
                print('   Anonymity range: [{}, {}]'.format(
                    bucket.min_anonymity, bucket.max_anonymity))
                print('   Size: {}'.format(bucket.bucket_size))
                for value_bucket in bucket.bucket_values:
                    print('   Values: {}'.format(
                        map(get_values, value_bucket.quasi_ids_values)))
                    print('   Estimated k-map anonymity: {}'.format(
                        value_bucket.estimated_anonymity))
            subscription.set_result(None)
        else:
            # This is not the message we're looking for.
            message.drop()

    # Instantiate a client.
    dlp = google.cloud.dlp.DlpServiceClient()

    # Convert the project id into a full resource id.
    parent = dlp.project_path(project)

    # Location info of the BigQuery table.
    source_table = {
        'project_id': table_project_id,
        'dataset_id': dataset_id,
        'table_id': table_id
    }

    # Check that numbers of quasi-ids and info types are equal
    if len(quasi_ids) != len(info_types):
        raise ValueError("""Number of infoTypes and number of quasi-identifiers
                            must be equal!""")

    # Convert quasi id list to Protobuf type
    def map_fields(quasi_id, info_type):
        return {'field': {'name': quasi_id}, 'info_type': {'name': info_type}}

    quasi_ids = map(map_fields, quasi_ids, info_types)

    # Tell the API where to send a notification when the job is complete.
    actions = [{
        'pub_sub': {'topic': '{}/topics/{}'.format(parent, topic_id)}
    }]

    # Configure risk analysis job
    # Give the name of the numeric column to compute risk metrics for
    risk_job = {
        'privacy_metric': {
            'k_map_estimation_config': {
                'quasi_ids': quasi_ids,
                'region_code': region_code
            }
        },
        'source_table': source_table,
        'actions': actions
    }

    # Create a Pub/Sub client and find the subscription. The subscription is
    # expected to already be listening to the topic.
    subscriber = google.cloud.pubsub.SubscriberClient()
    subscription_path = subscriber.subscription_path(
        project, subscription_id)
    subscription = subscriber.subscribe(subscription_path, callback)

    # Call API to start risk analysis job
    operation = dlp.create_dlp_job(parent, risk_job=risk_job)

    try:
        subscription.result(timeout=timeout)
    except TimeoutError:
        print('No event received before the timeout. Please verify that the '
              'subscription provided is subscribed to the topic provided.')
        subscription.close()

Go

// riskKMap runs K Map on the given data.
func riskKMap(w io.Writer, client *dlp.Client, project, dataProject, pubSubTopic, pubSubSub, datasetID, tableID, region string, columnNames ...string) {
	ctx := context.Background()

	// Create a PubSub Client used to listen for when the inspect job finishes.
	pClient, err := pubsub.NewClient(ctx, project)
	if err != nil {
		log.Fatalf("Error creating PubSub client: %v", err)
	}
	defer pClient.Close()

	// Create a PubSub subscription we can use to listen for messages.
	s, err := setupPubSub(ctx, pClient, project, pubSubTopic, pubSubSub)
	if err != nil {
		log.Fatalf("Error setting up PubSub: %v\n", err)
	}

	// topic is the PubSub topic string where messages should be sent.
	topic := "projects/" + project + "/topics/" + pubSubTopic

	// Build the QuasiID slice.
	var q []*dlppb.PrivacyMetric_KMapEstimationConfig_TaggedField
	for _, c := range columnNames {
		q = append(q, &dlppb.PrivacyMetric_KMapEstimationConfig_TaggedField{
			Field: &dlppb.FieldId{
				Name: c,
			},
			Tag: &dlppb.PrivacyMetric_KMapEstimationConfig_TaggedField_Inferred{
				Inferred: &empty.Empty{},
			},
		})
	}

	// Create a configured request.
	req := &dlppb.CreateDlpJobRequest{
		Parent: "projects/" + project,
		Job: &dlppb.CreateDlpJobRequest_RiskJob{
			RiskJob: &dlppb.RiskAnalysisJobConfig{
				// PrivacyMetric configures what to compute.
				PrivacyMetric: &dlppb.PrivacyMetric{
					Type: &dlppb.PrivacyMetric_KMapEstimationConfig_{
						KMapEstimationConfig: &dlppb.PrivacyMetric_KMapEstimationConfig{
							QuasiIds:   q,
							RegionCode: region,
						},
					},
				},
				// SourceTable describes where to find the data.
				SourceTable: &dlppb.BigQueryTable{
					ProjectId: dataProject,
					DatasetId: datasetID,
					TableId:   tableID,
				},
				// Send a message to PubSub using Actions.
				Actions: []*dlppb.Action{
					{
						Action: &dlppb.Action_PubSub{
							PubSub: &dlppb.Action_PublishToPubSub{
								Topic: topic,
							},
						},
					},
				},
			},
		},
	}
	// Create the risk job.
	j, err := client.CreateDlpJob(context.Background(), req)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Fprintf(w, "Created job: %v\n", j.GetName())

	// Wait for the risk job to finish by waiting for a PubSub message.
	ctx, cancel := context.WithCancel(ctx)
	err = s.Receive(ctx, func(ctx context.Context, msg *pubsub.Message) {
		// If this is the wrong job, do not process the result.
		if msg.Attributes["DlpJobName"] != j.GetName() {
			msg.Nack()
			return
		}
		msg.Ack()
		time.Sleep(500 * time.Millisecond)
		j, err := client.GetDlpJob(ctx, &dlppb.GetDlpJobRequest{
			Name: j.GetName(),
		})
		if err != nil {
			log.Fatalf("Error getting completed job: %v\n", err)
		}
		h := j.GetRiskDetails().GetKMapEstimationResult().GetKMapEstimationHistogram()
		for i, b := range h {
			fmt.Fprintf(w, "Histogram bucket %v\n", i)
			fmt.Fprintf(w, "  Anonymity range: [%v,%v]\n", b.GetMaxAnonymity(), b.GetMaxAnonymity())
			fmt.Fprintf(w, "  %v unique values total\n", b.GetBucketSize())
			for _, v := range b.GetBucketValues() {
				var qvs []string
				for _, qv := range v.GetQuasiIdsValues() {
					qvs = append(qvs, qv.String())
				}
				fmt.Fprintf(w, "    QuasiID values: %s\n", strings.Join(qvs, ", "))
				fmt.Fprintf(w, "    Estimated anonymity: %v\n", v.GetEstimatedAnonymity())
			}
		}
		// Stop listening for more messages.
		cancel()
	})
	if err != nil {
		log.Fatalf("Error receiving from PubSub: %v\n", err)
	}
}

PHP

/**
 * Computes the k-map risk estimation of a column set in a Google BigQuery table.
 */
use Google\Cloud\Core\ExponentialBackoff;
use Google\Cloud\Dlp\V2\DlpServiceClient;
use Google\Cloud\Dlp\V2\InfoType;
use Google\Cloud\Dlp\V2\RiskAnalysisJobConfig;
use Google\Cloud\Dlp\V2\BigQueryTable;
use Google\Cloud\Dlp\V2\DlpJob\JobState;
use Google\Cloud\Dlp\V2\Action;
use Google\Cloud\Dlp\V2\Action\PublishToPubSub;
use Google\Cloud\Dlp\V2\PrivacyMetric\KMapEstimationConfig;
use Google\Cloud\Dlp\V2\PrivacyMetric\KMapEstimationConfig\TaggedField;
use Google\Cloud\Dlp\V2\PrivacyMetric;
use Google\Cloud\Dlp\V2\FieldId;
use Google\Cloud\PubSub\PubSubClient;

/** Uncomment and populate these variables in your code */
// $callingProjectId = 'The project ID to run the API call under';
// $dataProjectId = 'The project ID containing the target Datastore';
// $topicId = 'The name of the Pub/Sub topic to notify once the job completes';
// $subscriptionId = 'The name of the Pub/Sub subscription to use when listening for job';
// $datasetId = 'The ID of the dataset to inspect';
// $tableId = 'The ID of the table to inspect';
// $regionCode = 'The ISO 3166-1 region code that the data is representative of';
// $quasiIdNames = ['array columns that form a composite key (quasi-identifiers)'];
// $infoTypes = ['array of infoTypes corresponding to the chosen quasi-identifiers'];

// Instantiate a client.
$dlp = new DlpServiceClient([
    'projectId' => $callingProjectId,
]);
$pubsub = new PubSubClient([
    'projectId' => $callingProjectId,
]);
$topic = $pubsub->topic($topicId);

// Verify input
if (count($infoTypes) != count($quasiIdNames)) {
    throw new Exception('Number of infoTypes and number of quasi-identifiers must be equal!');
}

// Map infoTypes to quasi-ids
$quasiIdObjects = array_map(function ($quasiId, $infoType) {
    $quasiIdField = (new FieldId())
        ->setName($quasiId);

    $quasiIdType = (new InfoType())
        ->setName($infoType);

    $quasiIdObject = (new TaggedField())
        ->setInfoType($quasiIdType)
        ->setField($quasiIdField);

    return $quasiIdObject;
}, $quasiIdNames, $infoTypes);

// Construct analysis config
$statsConfig = (new KMapEstimationConfig())
    ->setQuasiIds($quasiIdObjects)
    ->setRegionCode($regionCode);

$privacyMetric = (new PrivacyMetric())
    ->setKMapEstimationConfig($statsConfig);

// Construct items to be analyzed
$bigqueryTable = (new BigQueryTable())
    ->setProjectId($dataProjectId)
    ->setDatasetId($datasetId)
    ->setTableId($tableId);

// Construct the action to run when job completes
$pubSubAction = (new PublishToPubSub())
    ->setTopic($topic->name());

$action = (new Action())
    ->setPubSub($pubSubAction);

// Construct risk analysis job config to run
$riskJob = (new RiskAnalysisJobConfig())
    ->setPrivacyMetric($privacyMetric)
    ->setSourceTable($bigqueryTable)
    ->setActions([$action]);

// Listen for job notifications via an existing topic/subscription.
$subscription = $topic->subscription($subscriptionId);

// Submit request
$parent = $dlp->projectName($callingProjectId);
$job = $dlp->createDlpJob($parent, [
    'riskJob' => $riskJob
]);

// Poll Pub/Sub using exponential backoff until job finishes
$backoff = new ExponentialBackoff(20);
$backoff->execute(function () use ($subscription, $dlp, &$job) {
    printf('Waiting for job to complete' . PHP_EOL);
    foreach ($subscription->pull() as $message) {
        if (isset($message->attributes()['DlpJobName']) &&
            $message->attributes()['DlpJobName'] === $job->getName()) {
            $subscription->acknowledge($message);
            // Get the updated job. Loop to avoid race condition with DLP API.
            do {
                $job = $dlp->getDlpJob($job->getName());
            } while ($job->getState() == JobState::RUNNING);
            return true;
        }
    }
    throw new Exception('Job has not yet completed');
});

// Print finding counts
printf('Job %s status: %s' . PHP_EOL, $job->getName(), JobState::name($job->getState()));
switch ($job->getState()) {
    case JobState::DONE:
        $histBuckets = $job->getRiskDetails()->getKMapEstimationResult()->getKMapEstimationHistogram();

        foreach ($histBuckets as $bucketIndex => $histBucket) {
            // Print bucket stats
            printf('Bucket %s:' . PHP_EOL, $bucketIndex);
            printf(
                '  Anonymity range: [%s, %s]' . PHP_EOL,
                $histBucket->getMinAnonymity(),
                $histBucket->getMaxAnonymity()
            );
            printf('  Size: %s' . PHP_EOL, $histBucket->getBucketSize());

            // Print bucket values
            foreach ($histBucket->getBucketValues() as $percent => $valueBucket) {
                printf(
                    '  Estimated k-map anonymity: %s' . PHP_EOL,
                    $valueBucket->getEstimatedAnonymity()
                );

                // Pretty-print quasi-ID values
                print('  Values: ' . PHP_EOL);
                foreach ($valueBucket->getQuasiIdsValues() as $index => $value) {
                    print('    ' . $value->serializeToJsonString() . PHP_EOL);
                }
            }
        }
        break;
    case JobState::FAILED:
        printf('Job %s had errors:' . PHP_EOL, $job->getName());
        $errors = $job->getErrors();
        foreach ($errors as $error) {
            var_dump($error->getDetails());
        }
        break;
    default:
        print('Unexpected job state. Most likely, the job is either running or has not yet started.');
}

C#

public static object KMap(
    string callingProjectId,
    string tableProjectId,
    string datasetId,
    string tableId,
    string topicId,
    string subscriptionId,
    IEnumerable<FieldId> quasiIds,
    IEnumerable<InfoType> infoTypes,
    string regionCode)
{
    DlpServiceClient dlp = DlpServiceClient.Create();

    // Construct + submit the job
    var kmapEstimationConfig = new KMapEstimationConfig
    {
        QuasiIds =
        {
            quasiIds.Zip(
                infoTypes,
                (Field, InfoType) => new TaggedField
                {
                    Field = Field,
                    InfoType = InfoType
                }
            )
        },
        RegionCode = regionCode
    };

    var config = new RiskAnalysisJobConfig()
    {
        PrivacyMetric = new PrivacyMetric
        {
            KMapEstimationConfig = kmapEstimationConfig
        },
        SourceTable = new BigQueryTable
        {
            ProjectId = tableProjectId,
            DatasetId = datasetId,
            TableId = tableId
        },
        Actions =
        {
            new Google.Cloud.Dlp.V2.Action
            {
                PubSub = new PublishToPubSub
                {
                    Topic = $"projects/{callingProjectId}/topics/{topicId}"
                }
            }
        }
    };

    var submittedJob = dlp.CreateDlpJob(
        new CreateDlpJobRequest
        {
            ParentAsProjectName = new ProjectName(callingProjectId),
            RiskJob = config
        });

    // Listen to pub/sub for the job
    var subscriptionName = new SubscriptionName(
        callingProjectId,
        subscriptionId);
    SubscriberClient subscriber = SubscriberClient.CreateAsync(
        subscriptionName).Result;

    // SimpleSubscriber runs your message handle function on multiple
    // threads to maximize throughput.
    var done = new ManualResetEventSlim(false);
    subscriber.StartAsync((PubsubMessage message, CancellationToken cancel) =>
    {
        if (message.Attributes["DlpJobName"] == submittedJob.Name)
        {
            Thread.Sleep(500); // Wait for DLP API results to become consistent
            done.Set();
            return Task.FromResult(SubscriberClient.Reply.Ack);
        }
        else
        {
            return Task.FromResult(SubscriberClient.Reply.Nack);
        }
    });

    done.Wait(TimeSpan.FromMinutes(10)); // 10 minute timeout; may not work for large jobs
    subscriber.StopAsync(CancellationToken.None).Wait();

    // Process results
    var resultJob = dlp.GetDlpJob(new GetDlpJobRequest
    {
        DlpJobName = DlpJobName.Parse(submittedJob.Name)
    });

    var result = resultJob.RiskDetails.KMapEstimationResult;

    for (int histogramIdx = 0; histogramIdx < result.KMapEstimationHistogram.Count; histogramIdx++)
    {
        var histogramValue = result.KMapEstimationHistogram[histogramIdx];
        Console.WriteLine($"Bucket {histogramIdx}");
        Console.WriteLine($"  Anonymity range: [{histogramValue.MinAnonymity}, {histogramValue.MaxAnonymity}].");
        Console.WriteLine($"  Size: {histogramValue.BucketSize}");

        foreach (var datapoint in histogramValue.BucketValues)
        {
            // 'UnpackValue(x)' is a prettier version of 'x.toString()'
            Console.WriteLine($"    Values: [{String.Join(',', datapoint.QuasiIdsValues.Select(x => DlpSamplesUtils.UnpackValue(x)))}]");
            Console.WriteLine($"    Estimated k-map anonymity: {datapoint.EstimatedAnonymity}");
        }
    }

    return 0;
}

Computing δ-presence estimates with the Cloud DLP

Delta-presence (δ-presence) is a metric that quantifies the probability that an individual belongs to an analyzed dataset. Like k-map, you can estimate δ-presence values using Cloud DLP, which uses a statistical model to estimate the attack dataset. This is in contrast to the other risk analysis methods, in which the attack dataset is explicitly known. Depending on the type of data, Cloud DLP uses publicly available datasets (for example, from the US Census) or a custom statistical model (for example, one or more BigQuery tables that you specify), or it extrapolates from the distribution of values in your input dataset.

To compute a δ-presence estimate using Cloud DLP, first follow the instructions in the previous section, Risk analysis using Cloud DLP.

Within the DeltaPresenceEstimationConfig object, you specify the following:

  • quasiIds[]: Required. Fields (QuasiId objects) considered to be quasi-identifiers to scan and use to compute δ-presence. No two columns can have the same tag. These can be any of the following:

    • An infoType: This causes Cloud DLP to use the relevant public dataset as a statistical model of population, including US ZIP codes, region codes, ages, and genders.
    • A custom infoType: A custom tag wherein you indicate an auxiliary table (an AuxiliaryTable object) that contains statistical information about the possible values of this column.
    • The inferred tag: If no semantic tag is indicated, specify inferred. Cloud DLP infers the statistical model from the distribution of values in the input data.
  • regionCode: An ISO 3166-1 alpha-2 region code for Cloud DLP to use in statistical modeling. This value is required if no column is tagged with a region-specific infoType (for example, a US ZIP code) or a region code.

  • auxiliaryTables[]: Auxiliary tables (StatisticalTable objects) to use in the analysis. Each custom tag used to tag a quasi-identifier column (from quasiIds[]) must appear in exactly one column of one auxiliary table.

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