class PrivacyEncoder

class PrivacyEncoder

Defined at line 27 of file ../../third_party/cobalt/src/logger/privacy_encoder.h

The PrivacyEncoder is used by the ObservationGenerator to add privacy to

Observations (of any non-private observation type) generated by local

aggregation procedures. The PrivateIndexObservations produced by the

PrivacyEncoder are then written to the ObservationStore by the

ObservationGenerator's ObservationWriter.

|secure_gen| is used to perform the privacy encoding and therefore needs to be cryptographically

secure.

|gen| is used to perform non-deterministic encodings prior to the privacy encoding and therefore

does not need to be cryptographically secure.

Public Methods

void PrivacyEncoder (std::unique_ptr<SecureBitGeneratorInterface<uint32_t>> secure_gen, std::unique_ptr<BitGeneratorInterface<uint32_t>> gen)
std::unique_ptr<PrivacyEncoder> MakeSecurePrivacyEncoder ()

Returns a PrivacyEncoder with a private random number generator.

lib::statusor::StatusOr<std::vector<std::unique_ptr<Observation>>> MaybeMakePrivateObservations (std::unique_ptr<Observation> observation, const MetricDefinition & metric_def, const ReportDefinition & report_def)

If the report definition does not specify a privacy level, MaybeMakeObservations returns

|observation|. Else, MaybeMakeObservations transforms a user contribution for a local

aggregation period into a list of private observations. If the local aggregation produced an

Observation for the period, then this should be passed as

|observation|. If not (i.e. if no events were logged during the

aggregation period), then |observation| should be nullptr.

lib::statusor::StatusOr<uint64_t> MaxIndexForReport (const MetricDefinition & metric_def, const ReportDefinition & report_def)

Returns the maximum index of a PrivateIndexObservation for the metric and report specified by

|metric_def| and |report_def|.

lib::statusor::StatusOr<uint32_t> GetNumHistogramBuckets (const IntegerBuckets & int_buckets)

Returns the number of histogram buckets associated to an IntegerBuckets, including the

underflow and overflow buckets.

lib::statusor::StatusOr<size_t> GetNumCountMinCellsPerHash (const ReportDefinition & report_def)

The number of sketch cells per hash function in CountMin sketch for a StringCounts or a

UniqueDeviceStringCounts report |report_def|. Currently hard-coded to 10. Returns an error

status if |report_def| is not of type StringCounts or UniqueDeviceStringCounts.

lib::statusor::StatusOr<size_t> GetNumCountMinHashes (const ReportDefinition & report_def)

The number of hash functions in a CountMin sketch for a StringCounts or a

UniqueDeviceStringCounts report |report_def|. Currently hard-coded to 5. Returns an error

status if |report_def| is not of type StringCounts or UniqueDeviceStringCounts.

void ~PrivacyEncoder ()

Defined at line 35 of file ../../third_party/cobalt/src/logger/privacy_encoder.h

Friends

class PrivacyEncoderTest