| // Copyright 2020 Google LLC |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #include "third_party/private_membership/src/private_membership_rlwe_client.h" |
| |
| #include <algorithm> |
| #include <iterator> |
| #include <memory> |
| #include <optional> |
| #include <string> |
| #include <utility> |
| #include <vector> |
| |
| #include "third_party/private-join-and-compute/src/crypto/ec_commutative_cipher.h" |
| #include "third_party/private_membership/src/internal/crypto_utils.h" |
| #include "third_party/private_membership/src/private_membership.pb.h" |
| #include "third_party/private_membership/src/private_membership_rlwe.pb.h" |
| #include "third_party/private_membership/src/internal/constants.h" |
| #include "third_party/private_membership/src/internal/encrypted_bucket_id.h" |
| #include "third_party/private_membership/src/internal/hashed_bucket_id.h" |
| #include "third_party/private_membership/src/internal/rlwe_id_utils.h" |
| #include "third_party/private_membership/src/internal/rlwe_params.h" |
| #include "third_party/private_membership/src/internal/utils.h" |
| #include "absl/container/flat_hash_map.h" |
| #include "absl/container/flat_hash_set.h" |
| #include "absl/status/statusor.h" |
| #include "absl/strings/string_view.h" |
| #include "third_party/shell-encryption/src/polynomial.h" |
| #include "third_party/shell-encryption/src/status_macros.h" |
| #include "third_party/shell-encryption/src/symmetric_encryption_with_prng.h" |
| #include "third_party/shell-encryption/src/transcription.h" |
| |
| namespace private_membership { |
| namespace rlwe { |
| |
| ::rlwe::StatusOr<std::unique_ptr<PrivateMembershipRlweClient>> |
| PrivateMembershipRlweClient::Create( |
| private_membership::rlwe::RlweUseCase use_case, |
| const std::vector<RlwePlaintextId>& plaintext_ids) { |
| return CreateInternal(use_case, plaintext_ids, std::optional<std::string>(), |
| internal::PrngSeedGenerator::Create(), |
| internal::SecurePrngGenerator::Create()); |
| } |
| |
| ::rlwe::StatusOr<std::unique_ptr<PrivateMembershipRlweClient>> |
| PrivateMembershipRlweClient::CreateForTesting( |
| private_membership::rlwe::RlweUseCase use_case, |
| const std::vector<RlwePlaintextId>& plaintext_ids, |
| absl::string_view ec_cipher_key, absl::string_view seed) { |
| RLWE_ASSIGN_OR_RETURN(auto prng_seed_generator, |
| internal::PrngSeedGenerator::CreateDeterministic(seed)); |
| return CreateInternal( |
| use_case, plaintext_ids, std::optional<std::string>(ec_cipher_key), |
| std::move(prng_seed_generator), internal::SecurePrngGenerator::Create()); |
| } |
| |
| ::rlwe::StatusOr<std::unique_ptr<PrivateMembershipRlweClient>> |
| PrivateMembershipRlweClient::CreateInternal( |
| private_membership::rlwe::RlweUseCase use_case, |
| const std::vector<RlwePlaintextId>& plaintext_ids, |
| std::optional<std::string> ec_cipher_key, |
| std::unique_ptr<internal::PrngSeedGenerator> prng_seed_generator, |
| std::unique_ptr<internal::PrngGenerator> prng_generator) { |
| if (use_case == private_membership::rlwe::RLWE_USE_CASE_UNDEFINED) { |
| return absl::InvalidArgumentError("Use case must be defined."); |
| } |
| if (plaintext_ids.empty()) { |
| return absl::InvalidArgumentError("Plaintext ids must not be empty."); |
| } |
| |
| // Remove duplicate IDs. |
| absl::flat_hash_set<std::string> hashed_rlwe_plaintext_ids; |
| std::vector<RlwePlaintextId> unique_plaintext_ids; |
| for (int i = 0; i < plaintext_ids.size(); ++i) { |
| std::string hash = HashRlwePlaintextId(plaintext_ids[i]); |
| if (!hashed_rlwe_plaintext_ids.contains(hash)) { |
| unique_plaintext_ids.push_back(plaintext_ids[i]); |
| } |
| hashed_rlwe_plaintext_ids.insert(hash); |
| } |
| |
| // Create the cipher with new key or from existing key depending on whether |
| // the key was provided. |
| auto ec_cipher = |
| ec_cipher_key.has_value() |
| ? ::private_join_and_compute::ECCommutativeCipher::CreateFromKey( |
| kCurveId, ec_cipher_key.value(), |
| ::private_join_and_compute::ECCommutativeCipher::HashType::SHA256) |
| : ::private_join_and_compute::ECCommutativeCipher::CreateWithNewKey( |
| kCurveId, ::private_join_and_compute::ECCommutativeCipher::HashType::SHA256); |
| if (!ec_cipher.ok()) { |
| return ec_cipher.status(); |
| } |
| |
| return absl::WrapUnique<PrivateMembershipRlweClient>( |
| new PrivateMembershipRlweClient( |
| use_case, unique_plaintext_ids, std::move(ec_cipher).value(), |
| std::move(prng_seed_generator), std::move(prng_generator))); |
| } |
| |
| PrivateMembershipRlweClient::PrivateMembershipRlweClient( |
| private_membership::rlwe::RlweUseCase use_case, |
| const std::vector<RlwePlaintextId>& plaintext_ids, |
| std::unique_ptr<::private_join_and_compute::ECCommutativeCipher> ec_cipher, |
| std::unique_ptr<internal::PrngSeedGenerator> prng_seed_generator, |
| std::unique_ptr<internal::PrngGenerator> prng_generator) |
| : use_case_(use_case), |
| plaintext_ids_(plaintext_ids), |
| ec_cipher_(std::move(ec_cipher)), |
| prng_seed_generator_(std::move(prng_seed_generator)), |
| prng_generator_(std::move(prng_generator)) {} |
| |
| ::rlwe::StatusOr<private_membership::rlwe::PrivateMembershipRlweOprfRequest> |
| PrivateMembershipRlweClient::CreateOprfRequest() { |
| private_membership::rlwe::PrivateMembershipRlweOprfRequest request; |
| request.set_use_case(use_case_); |
| // Encrypt the plaintext ids with the client generated key. |
| for (const auto& plaintext_id : plaintext_ids_) { |
| std::string whole_id = HashRlwePlaintextId(plaintext_id); |
| auto client_encrypted_id = ec_cipher_->Encrypt(whole_id); |
| if (!client_encrypted_id.ok()) { |
| return client_encrypted_id.status(); |
| } |
| *request.add_encrypted_ids() = client_encrypted_id.value(); |
| |
| // Populate the map of client encrypted id to plaintext id. |
| client_encrypted_id_to_plaintext_id_[client_encrypted_id.value()] = |
| plaintext_id; |
| } |
| return request; |
| } |
| |
| absl::Status PrivateMembershipRlweClient::ValidateOprfResponse( |
| const private_membership::rlwe::PrivateMembershipRlweOprfResponse& |
| oprf_response) const { |
| // Check for valid bucket ID lengths. |
| int encrypted_bucket_id_length = |
| oprf_response.encrypted_buckets_parameters().encrypted_bucket_id_length(); |
| if (encrypted_bucket_id_length < 0 || |
| encrypted_bucket_id_length > kMaxEncryptedBucketIdLength) { |
| return absl::InvalidArgumentError(absl::StrCat( |
| "Encrypted bucket ID length must be non-negative and at most ", |
| kMaxEncryptedBucketIdLength, ".")); |
| } |
| |
| // Check number of responses. |
| if (oprf_response.doubly_encrypted_ids_size() < |
| client_encrypted_id_to_plaintext_id_.size()) { |
| return absl::InvalidArgumentError( |
| "OPRF response missing a response to a requested ID."); |
| } else if (oprf_response.doubly_encrypted_ids_size() > |
| client_encrypted_id_to_plaintext_id_.size()) { |
| return absl::InvalidArgumentError( |
| "OPRF response contains too many responses."); |
| } |
| return absl::OkStatus(); |
| } |
| |
| ::rlwe::StatusOr<private_membership::rlwe::PrivateMembershipRlweQueryRequest> |
| PrivateMembershipRlweClient::CreateQueryRequest( |
| const private_membership::rlwe::PrivateMembershipRlweOprfResponse& |
| oprf_response) { |
| auto validation_result = ValidateOprfResponse(oprf_response); |
| if (!validation_result.ok()) { |
| return validation_result; |
| } |
| |
| // Initialize PIR client. |
| int encrypted_bucket_id_length = |
| oprf_response.encrypted_buckets_parameters().encrypted_bucket_id_length(); |
| int encrypted_buckets_count = 1 << encrypted_bucket_id_length; |
| RLWE_ASSIGN_OR_RETURN( |
| pir_client_, internal::PirClient::Create( |
| oprf_response.rlwe_parameters(), encrypted_buckets_count, |
| prng_seed_generator_.get(), prng_generator_.get())); |
| |
| private_membership::rlwe::PrivateMembershipRlweQueryRequest request; |
| request.set_use_case(use_case_); |
| request.set_key_version(oprf_response.key_version()); |
| |
| // Keep track of seen plaintext IDs to check for duplicates. |
| absl::flat_hash_set<std::string> seen_encrypted_ids; |
| |
| for (const auto& doubly_encrypted_id : oprf_response.doubly_encrypted_ids()) { |
| private_membership::rlwe::PrivateMembershipRlweQuery single_query; |
| single_query.set_queried_encrypted_id( |
| doubly_encrypted_id.queried_encrypted_id()); |
| const std::string& encrypted_id = |
| doubly_encrypted_id.queried_encrypted_id(); |
| |
| // Check validity of returned queried ID. |
| if (!client_encrypted_id_to_plaintext_id_.contains(encrypted_id)) { |
| return absl::InvalidArgumentError( |
| "OPRF response contains a response to an erroneous encrypted ID."); |
| } |
| |
| // Already processed a response for this encrypted ID. Ignore this one. |
| if (seen_encrypted_ids.contains(encrypted_id)) { |
| return absl::InvalidArgumentError( |
| "OPRF response contains duplicate responses for the same ID."); |
| } |
| seen_encrypted_ids.insert(encrypted_id); |
| |
| // Compute the hashed bucket id if the hashed bucket parameter is set in |
| // the response. |
| if (oprf_response.hashed_buckets_parameters().hashed_bucket_id_length() > |
| 0) { |
| const RlwePlaintextId& plaintext_id = |
| client_encrypted_id_to_plaintext_id_[encrypted_id]; |
| RLWE_ASSIGN_OR_RETURN( |
| HashedBucketId hashed_bucket_id, |
| HashedBucketId::Create(plaintext_id, |
| oprf_response.hashed_buckets_parameters(), |
| &context_)); |
| *single_query.mutable_hashed_bucket_id() = hashed_bucket_id.ToApiProto(); |
| } |
| |
| // Decrypt doubly encrypted id to retrieve id encrypted only by the server |
| // key. |
| auto server_encrypted_id = |
| ec_cipher_->Decrypt(doubly_encrypted_id.doubly_encrypted_id()); |
| if (!server_encrypted_id.ok()) { |
| return server_encrypted_id.status(); |
| } |
| |
| // Truncate the hash of the server encrypted id by the first |
| // encrypted_bucket_id_length bits to compute the encrypted bucket id. |
| RLWE_ASSIGN_OR_RETURN( |
| EncryptedBucketId encrypted_bucket_id_obj, |
| EncryptedBucketId::Create(server_encrypted_id.value(), |
| oprf_response.encrypted_buckets_parameters(), |
| &context_)); |
| RLWE_ASSIGN_OR_RETURN(int encrypted_bucket_id, |
| encrypted_bucket_id_obj.ToUint32()); |
| |
| // Create query request. |
| RLWE_ASSIGN_OR_RETURN(*single_query.mutable_pir_request(), |
| pir_client_->CreateRequest(encrypted_bucket_id)); |
| |
| client_encrypted_id_to_server_encrypted_id_[encrypted_id] = |
| std::move(server_encrypted_id).value(); |
| |
| *request.add_queries() = single_query; |
| } |
| |
| hashed_bucket_params_ = oprf_response.hashed_buckets_parameters(); |
| encrypted_bucket_params_ = oprf_response.encrypted_buckets_parameters(); |
| return request; |
| } |
| |
| absl::Status PrivateMembershipRlweClient::ValidateQueryResponse( |
| const private_membership::rlwe::PrivateMembershipRlweQueryResponse& |
| query_response) const { |
| // Check response length for missing responses. |
| if (query_response.pir_responses_size() < |
| client_encrypted_id_to_plaintext_id_.size()) { |
| return absl::InvalidArgumentError( |
| "Query response missing a response to a requested ID."); |
| } else if (query_response.pir_responses_size() > |
| client_encrypted_id_to_plaintext_id_.size()) { |
| return absl::InvalidArgumentError( |
| "Query response contains too many responses."); |
| } |
| return absl::OkStatus(); |
| } |
| |
| ::rlwe::StatusOr<RlweMembershipResponses> |
| PrivateMembershipRlweClient::ProcessQueryResponse( |
| const private_membership::rlwe::PrivateMembershipRlweQueryResponse& |
| query_response) { |
| auto validation_result = ValidateQueryResponse(query_response); |
| if (!validation_result.ok()) { |
| return validation_result; |
| } |
| |
| // Keep track of seen encrypted IDs to avoid duplicates. |
| absl::flat_hash_set<std::string> seen_encrypted_ids; |
| |
| RlweMembershipResponses membership_responses; |
| for (const auto& pir_response : query_response.pir_responses()) { |
| const std::string& encrypted_id = pir_response.queried_encrypted_id(); |
| if (!client_encrypted_id_to_plaintext_id_.contains(encrypted_id) || |
| !client_encrypted_id_to_server_encrypted_id_.contains(encrypted_id)) { |
| return absl::InvalidArgumentError( |
| "Query response contains a response to an erroneous encrypted ID."); |
| } |
| |
| // Already processed this encrypted ID. Ignore this one. |
| if (seen_encrypted_ids.contains(encrypted_id)) { |
| return absl::InvalidArgumentError( |
| "Query response contains duplicate responses for the same ID."); |
| } |
| seen_encrypted_ids.insert(encrypted_id); |
| |
| RLWE_ASSIGN_OR_RETURN( |
| std::vector<uint8_t> serialized_encrypted_bucket_byte, |
| pir_client_->ProcessResponse(pir_response.pir_response())); |
| |
| std::string serialized_encrypted_bucket; |
| if (!serialized_encrypted_bucket_byte.empty()) { |
| RLWE_ASSIGN_OR_RETURN(serialized_encrypted_bucket, |
| private_membership::Unpad(std::string( |
| serialized_encrypted_bucket_byte.begin(), |
| serialized_encrypted_bucket_byte.end()))); |
| } |
| |
| private_membership::rlwe::EncryptedBucket encrypted_bucket; |
| if (!serialized_encrypted_bucket.empty() && |
| !encrypted_bucket.ParseFromString(serialized_encrypted_bucket)) { |
| return absl::InternalError("Parsing serialized encrypted bucket failed."); |
| } |
| |
| // Plaintext id associated with the client encrypted id. |
| const RlwePlaintextId& plaintext_id = |
| client_encrypted_id_to_plaintext_id_[encrypted_id]; |
| // Server key encrypted id associated with the client encrypted id. |
| const std::string& server_encrypted_id = |
| client_encrypted_id_to_server_encrypted_id_[encrypted_id]; |
| RLWE_ASSIGN_OR_RETURN(auto membership, CheckMembership(server_encrypted_id, |
| encrypted_bucket)); |
| auto* response = membership_responses.add_membership_responses(); |
| *response->mutable_plaintext_id() = plaintext_id; |
| *response->mutable_membership_response() = membership; |
| } |
| |
| return membership_responses; |
| } |
| |
| ::rlwe::StatusOr<private_membership::MembershipResponse> |
| PrivateMembershipRlweClient::CheckMembership( |
| absl::string_view server_encrypted_id, |
| const private_membership::rlwe::EncryptedBucket& encrypted_bucket) { |
| private_membership::MembershipResponse membership_response; |
| RLWE_ASSIGN_OR_RETURN( |
| std::string to_match_hash, |
| ComputeBucketStoredEncryptedId(server_encrypted_id, |
| encrypted_bucket_params_, &context_)); |
| for (const auto& encrypted_id_value_pair : |
| encrypted_bucket.encrypted_id_value_pairs()) { |
| const auto& encrypted_id = encrypted_id_value_pair.encrypted_id(); |
| // Check encrypted_id is a prefix of to_match_hash. If it is, then the id |
| // is a member. |
| if (std::equal(encrypted_id.begin(), encrypted_id.end(), |
| to_match_hash.begin())) { |
| membership_response.set_is_member(true); |
| if (!encrypted_id_value_pair.encrypted_value().empty()) { |
| RLWE_ASSIGN_OR_RETURN( |
| std::string decrypted_value, |
| private_membership::DecryptValue( |
| server_encrypted_id, encrypted_id_value_pair.encrypted_value(), |
| &context_)); |
| membership_response.set_value(decrypted_value); |
| } |
| break; |
| } |
| } |
| return membership_response; |
| } |
| |
| namespace internal { |
| |
| std::unique_ptr<PrngSeedGenerator> PrngSeedGenerator::Create() { |
| return absl::WrapUnique<PrngSeedGenerator>(new PrngSeedGenerator()); |
| } |
| |
| ::rlwe::StatusOr<std::unique_ptr<PrngSeedGenerator>> |
| PrngSeedGenerator::CreateDeterministic(absl::string_view seed) { |
| RLWE_ASSIGN_OR_RETURN(auto prng_seed_generator, |
| SingleThreadPrng::Create(seed)); |
| return absl::WrapUnique<PrngSeedGenerator>( |
| new PrngSeedGenerator(std::move(prng_seed_generator))); |
| } |
| |
| ::rlwe::StatusOr<std::string> PrngSeedGenerator::GeneratePrngSeed() const { |
| if (deterministic_prng_seed_generator_.has_value()) { |
| std::string res(SingleThreadPrng::SeedLength(), 0); |
| for (int i = 0; i < res.length(); ++i) { |
| RLWE_ASSIGN_OR_RETURN( |
| res[i], deterministic_prng_seed_generator_.value()->Rand8()); |
| } |
| return res; |
| } |
| return SingleThreadPrng::GenerateSeed(); |
| } |
| |
| PrngSeedGenerator::PrngSeedGenerator( |
| std::unique_ptr<SingleThreadPrng> prng_seed_generator) |
| : deterministic_prng_seed_generator_( |
| std::optional<std::unique_ptr<SingleThreadPrng>>( |
| std::move(prng_seed_generator))) {} |
| |
| template <typename ModularInt> |
| ::rlwe::StatusOr<std::unique_ptr<PirClientImpl<ModularInt>>> |
| PirClientImpl<ModularInt>::Create(const RlweParameters& rlwe_params, |
| int total_entry_count, |
| const PrngSeedGenerator* prng_seed_generator, |
| const PrngGenerator* prng_generator) { |
| if (rlwe_params.log_degree() < 0 || |
| rlwe_params.log_degree() > kMaxLogDegree) { |
| return absl::InvalidArgumentError( |
| "Degree must be positive and at most 2^20."); |
| } |
| int levels_of_recursion = rlwe_params.levels_of_recursion(); |
| if (levels_of_recursion <= 0 || levels_of_recursion > kMaxLevelsOfRecursion) { |
| return absl::InvalidArgumentError( |
| absl::StrCat("Levels of recursion, ", levels_of_recursion, |
| ", must be positive and at most ", kMaxLevelsOfRecursion)); |
| } |
| // Create parameters. |
| std::vector<std::unique_ptr<const typename ModularInt::Params>> |
| modulus_params; |
| modulus_params.reserve(rlwe_params.modulus_size()); |
| std::vector<std::unique_ptr<const ::rlwe::NttParameters<ModularInt>>> |
| ntt_params; |
| ntt_params.reserve(rlwe_params.modulus_size()); |
| std::vector<std::unique_ptr<const ::rlwe::ErrorParams<ModularInt>>> |
| error_params; |
| error_params.reserve(rlwe_params.modulus_size()); |
| for (int i = 0; i < rlwe_params.modulus_size(); ++i) { |
| RLWE_ASSIGN_OR_RETURN( |
| auto temp_modulus_params, |
| CreateModulusParams<ModularInt>(rlwe_params.modulus(i))); |
| modulus_params.push_back(std::move(temp_modulus_params)); |
| RLWE_ASSIGN_OR_RETURN( |
| auto temp_ntt_params, |
| CreateNttParams<ModularInt>(rlwe_params, modulus_params[i].get())); |
| ntt_params.push_back(std::move(temp_ntt_params)); |
| RLWE_ASSIGN_OR_RETURN( |
| auto temp_error_params, |
| CreateErrorParams<ModularInt>(rlwe_params, modulus_params[i].get(), |
| ntt_params[i].get())); |
| error_params.push_back(std::move(temp_error_params)); |
| } |
| |
| RLWE_ASSIGN_OR_RETURN(std::string prng_seed, |
| prng_seed_generator->GeneratePrngSeed()); |
| RLWE_ASSIGN_OR_RETURN(auto prng, prng_generator->CreatePrng(prng_seed)); |
| RLWE_ASSIGN_OR_RETURN( |
| auto key, |
| ::rlwe::SymmetricRlweKey<ModularInt>::Sample( |
| rlwe_params.log_degree(), rlwe_params.variance(), rlwe_params.log_t(), |
| modulus_params[0].get(), ntt_params[0].get(), prng.get())); |
| |
| return absl::WrapUnique<>(new PirClientImpl( |
| rlwe_params, std::move(modulus_params), std::move(ntt_params), |
| std::move(error_params), key, total_entry_count, prng_seed_generator, |
| prng_generator)); |
| } |
| |
| template <typename ModularInt> |
| PirClientImpl<ModularInt>::PirClientImpl( |
| const RlweParameters& rlwe_params, |
| std::vector<std::unique_ptr<const typename ModularInt::Params>> |
| modulus_params, |
| std::vector<std::unique_ptr<const ::rlwe::NttParameters<ModularInt>>> |
| ntt_params, |
| std::vector<std::unique_ptr<const ::rlwe::ErrorParams<ModularInt>>> |
| error_params, |
| const ::rlwe::SymmetricRlweKey<ModularInt>& key, int total_entry_count, |
| const PrngSeedGenerator* prng_seed_generator, |
| const PrngGenerator* prng_generator) |
| : rlwe_params_(rlwe_params), |
| modulus_params_(std::move(modulus_params)), |
| ntt_params_(std::move(ntt_params)), |
| error_params_(std::move(error_params)), |
| key_(key), |
| total_entry_count_(total_entry_count), |
| prng_seed_generator_(prng_seed_generator), |
| prng_generator_(prng_generator) {} |
| |
| template <typename ModularInt> |
| ::rlwe::StatusOr<PirRequest> PirClientImpl<ModularInt>::CreateRequest( |
| int index) { |
| if (index < 0 || index >= total_entry_count_) { |
| return absl::InvalidArgumentError("Index out of bounds."); |
| } |
| |
| PirRequest req; |
| |
| // The number of virtual entries per level of recursion = the |
| // (levels_of_recursion)th root of the number of items in the database. |
| double exact_entries_per_level = |
| pow(total_entry_count_, 1.0 / rlwe_params_.levels_of_recursion()); |
| // Round this number up to the nearest whole integer. |
| int branching_factor = static_cast<int>(ceil(exact_entries_per_level)); |
| |
| // Create the ciphertexts for each level of recursion. This two-dimensional |
| // table is flattened when it is put into the proto. |
| |
| // Determine the number of actual database items stored in each virtual |
| // database block at this level. This is the number of items remaining |
| // divided by the branching factor, rounded up. |
| int items_in_block = |
| (total_entry_count_ + branching_factor - 1) / branching_factor; |
| |
| // The index of the item we want to request at the current level of recursion. |
| int index_remaining = index; |
| |
| // Create useful zero polynomial. |
| std::vector<ModularInt> zeroes( |
| 1 << rlwe_params_.log_degree(), |
| ModularInt::ImportZero(modulus_params_[0].get())); |
| ::rlwe::Polynomial<ModularInt> zero_poly = |
| ::rlwe::Polynomial<ModularInt>(zeroes); |
| |
| // Create useful indicator polynomial. |
| std::vector<ModularInt> indicator(zeroes); |
| indicator[0] = ModularInt::ImportOne(modulus_params_[0].get()); |
| const ::rlwe::Polynomial<ModularInt> indicator_poly = |
| ::rlwe::Polynomial<ModularInt>::ConvertToNtt(indicator, *(ntt_params_[0]), |
| modulus_params_[0].get()); |
| |
| // Fill plaintext indicator vector with only zeroes at first. |
| if (branching_factor * rlwe_params_.levels_of_recursion() > |
| kMaxRequestEntries) { |
| return absl::InvalidArgumentError( |
| absl::StrCat("Number of request entries exceeds ", kMaxRequestEntries)); |
| } |
| std::vector<::rlwe::Polynomial<ModularInt>> plaintexts( |
| branching_factor * rlwe_params_.levels_of_recursion(), zero_poly); |
| |
| // Fill appropriate indicator for each level of recursion. |
| for (int level = 0; level < rlwe_params_.levels_of_recursion(); ++level) { |
| // Determine which block contains the item we wish to request. |
| int index_at_level = index_remaining / items_in_block; |
| int index_in_plaintext = (level * branching_factor) + index_at_level; |
| plaintexts[index_in_plaintext] = indicator_poly; |
| |
| // Determine the index of the desired item within that block. This is |
| // the index within the items that remain after this level of recursion. |
| index_remaining = index_remaining % items_in_block; |
| |
| // Update the block size for the next level of recursion. |
| items_in_block = (items_in_block + branching_factor - 1) / branching_factor; |
| } |
| |
| RLWE_ASSIGN_OR_RETURN(auto prng_seed, |
| prng_seed_generator_->GeneratePrngSeed()); |
| req.set_prng_seed(prng_seed); |
| RLWE_ASSIGN_OR_RETURN(auto prng, prng_generator_->CreatePrng(prng_seed)); |
| RLWE_ASSIGN_OR_RETURN(std::string prng_encryption_seed, |
| prng_seed_generator_->GeneratePrngSeed()); |
| RLWE_ASSIGN_OR_RETURN(auto prng_encryption, |
| prng_generator_->CreatePrng(prng_encryption_seed)); |
| RLWE_ASSIGN_OR_RETURN(std::vector<::rlwe::Polynomial<ModularInt>> ciphertexts, |
| ::rlwe::EncryptWithPrng(key_, plaintexts, prng.get(), |
| prng_encryption.get())); |
| for (int i = 0; i < ciphertexts.size(); ++i) { |
| RLWE_ASSIGN_OR_RETURN(*req.add_request(), |
| ciphertexts[i].Serialize(modulus_params_[0].get())); |
| } |
| |
| return req; |
| } |
| |
| template <typename ModularInt> |
| ::rlwe::StatusOr<std::vector<uint8_t>> |
| PirClientImpl<ModularInt>::ProcessResponse(const PirResponse& response) { |
| if (response.plaintext_entry_size() < 0 || |
| response.plaintext_entry_size() > kMaxPlaintextEntrySize) { |
| return absl::InvalidArgumentError( |
| "Invalid plaintext entry size that must be at most 10 MB in length."); |
| } |
| std::vector<uint8_t> raw_bytes; |
| for (int i = 0; i < response.response_size(); i++) { |
| const typename ModularInt::Params* decrypt_modulus_params; |
| const ::rlwe::NttParameters<ModularInt>* decrypt_ntt_params; |
| const ::rlwe::ErrorParams<ModularInt>* decrypt_error_params; |
| ::rlwe::SymmetricRlweKey<ModularInt> decrypt_key = key_; |
| if (modulus_params_.size() == 2) { |
| decrypt_modulus_params = modulus_params_[1].get(); |
| decrypt_ntt_params = ntt_params_[1].get(); |
| decrypt_error_params = error_params_[1].get(); |
| RLWE_ASSIGN_OR_RETURN( |
| decrypt_key, |
| key_.SwitchModulus(decrypt_modulus_params, decrypt_ntt_params)); |
| } else if (modulus_params_.size() == 1) { |
| decrypt_modulus_params = modulus_params_[0].get(); |
| decrypt_ntt_params = ntt_params_[0].get(); |
| decrypt_error_params = error_params_[0].get(); |
| } else { |
| return absl::InternalError("More than two moduli."); |
| } |
| RLWE_ASSIGN_OR_RETURN( |
| auto ciphertext, |
| ::rlwe::SymmetricRlweCiphertext<ModularInt>::Deserialize( |
| response.response(i), decrypt_modulus_params, |
| decrypt_error_params)); |
| RLWE_ASSIGN_OR_RETURN(std::vector<typename ModularInt::Int> plaintext, |
| ::rlwe::Decrypt(decrypt_key, ciphertext)); |
| RLWE_ASSIGN_OR_RETURN( |
| std::vector<uint8_t> column, |
| (::rlwe::TranscribeBits<typename ModularInt::Int, uint8_t>( |
| plaintext, key_.Len() * key_.BitsPerCoeff(), key_.BitsPerCoeff(), |
| 8))); |
| |
| raw_bytes.insert(raw_bytes.end(), std::make_move_iterator(column.begin()), |
| std::make_move_iterator(column.end())); |
| } |
| raw_bytes.resize(response.plaintext_entry_size()); |
| return raw_bytes; |
| } |
| |
| ::rlwe::StatusOr<std::unique_ptr<internal::PirClient>> |
| internal::PirClient::Create(const RlweParameters& rlwe_params, |
| int total_entry_count, |
| const PrngSeedGenerator* prng_seed_generator, |
| const PrngGenerator* prng_generator) { |
| if (rlwe_params.modulus_size() <= 0) { |
| return absl::InvalidArgumentError("Must provide at least one modulus."); |
| } |
| if (rlwe_params.modulus(0).hi() > 0 || |
| (rlwe_params.modulus(0).lo() >> 62) > 0) { |
| RLWE_ASSIGN_OR_RETURN( |
| auto client, PirClientImpl<ModularInt128>::Create( |
| rlwe_params, total_entry_count, prng_seed_generator, |
| prng_generator)); |
| return std::unique_ptr<internal::PirClient>(std::move(client)); |
| } else { |
| RLWE_ASSIGN_OR_RETURN( |
| auto client, PirClientImpl<ModularInt64>::Create( |
| rlwe_params, total_entry_count, prng_seed_generator, |
| prng_generator)); |
| return std::unique_ptr<internal::PirClient>(std::move(client)); |
| } |
| } |
| |
| template class PirClientImpl<ModularInt64>; |
| template class PirClientImpl<ModularInt128>; |
| |
| } // namespace internal |
| |
| } // namespace rlwe |
| } // namespace private_membership |