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Handle intersection when client is larger than server (#151)
* use the max of client and server inputs when computing the bits of the bloomfilter * fix gcs * typo * tests * cleanup * Update WASM tests * package lock * use min * fix * fix rollup * revert fpr * revert js tests * use better fpr
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-64
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13 files changed

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‎CHANGES.md‎

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@@ -1,3 +1,12 @@
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# Version 1.1.0
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Bugfix:
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- Fixed an issue when computing an intersection with the client's set **larger**
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than the server's set. In this case, the intersection reported more values
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than possible. e.g. computing an intersection with a client set of 100 values
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and server with 10 values sometimes resulted in 12.
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# Version 1.0.3
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Bugfix:

‎package-lock.json‎

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‎package.json‎

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@@ -1,6 +1,6 @@
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{
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"name": "@openmined/psi.js",
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"version": "1.0.3",
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"version": "1.1.0",
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"description": "Private Set Intersection for JavaScript",
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"repository": {
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"type": "git",

‎private_set_intersection/cpp/bloom_filter.cpp‎

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@@ -33,8 +33,12 @@ BloomFilter::BloomFilter(
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context_(std::move(context)) {}
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StatusOr<std::unique_ptr<BloomFilter>> BloomFilter::Create(
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double fpr, absl::Span<const std::string> elements) {
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ASSIGN_OR_RETURN(auto filter, CreateEmpty(fpr, elements.size()));
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double fpr, int64_t num_client_inputs,
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absl::Span<const std::string> elements) {
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auto num_server_inputs = static_cast<int64_t>(elements.size());
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ASSIGN_OR_RETURN(auto filter, CreateEmpty(fpr, std::max(num_client_inputs,
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num_server_inputs)));
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filter->Add(elements);
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// This move seems to be needed for some versions of GCC. See for example this
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// failing build:

‎private_set_intersection/cpp/bloom_filter.h‎

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Original file line numberDiff line numberDiff line change
@@ -45,7 +45,8 @@ class BloomFilter {
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BloomFilter() = delete;
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static StatusOr<std::unique_ptr<BloomFilter>> Create(
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double fpr, absl::Span<const std::string> elements);
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double fpr, int64_t num_client_inputs,
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absl::Span<const std::string> elements);
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// Creates a new Bloom filter. As long as less than `max_elements` are
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// inserted, the probability of false positives when performing checks

‎private_set_intersection/cpp/gcs.cpp‎

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@@ -35,12 +35,14 @@ GCS::GCS(std::string golomb, int64_t div, int64_t hash_range,
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context_(std::move(context)) {}
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StatusOr<std::unique_ptr<GCS>> GCS::Create(
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double fpr, absl::Span<const std::string> elements) {
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double fpr, int64_t num_client_inputs,
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absl::Span<const std::string> elements) {
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if (fpr <= 0 || fpr >= 1) {
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return absl::InvalidArgumentError("`fpr` must be in (0,1)");
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}
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auto hash_range = static_cast<int64_t>(elements.size() / fpr);
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auto num_server_inputs = static_cast<int64_t>(elements.size());
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auto hash_range = static_cast<int64_t>(
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std::max(num_client_inputs, num_server_inputs) / fpr);
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std::vector<int64_t> hashes;
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hashes.reserve(elements.size());
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auto context = absl::make_unique<::private_join_and_compute::Context>();

‎private_set_intersection/cpp/gcs.h‎

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Original file line numberDiff line numberDiff line change
@@ -33,7 +33,8 @@ class GCS {
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GCS() = delete;
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static StatusOr<std::unique_ptr<GCS>> Create(
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double fpr, absl::Span<const std::string> elements);
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double fpr, int64_t num_client_inputs,
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absl::Span<const std::string> elements);
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static StatusOr<std::unique_ptr<GCS>> CreateFromProtobuf(
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const psi_proto::ServerSetup& encoded_set);

‎private_set_intersection/cpp/gcs_test.cpp‎

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Original file line numberDiff line numberDiff line change
@@ -30,13 +30,15 @@ namespace {
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TEST(GCSTest, TestIntersect) {
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std::vector<std::string> elements = {"a", "b", "c", "d"};
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std::vector<std::string> elements2 = {"a", "b", "d", "e"};
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auto max_inputs =
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static_cast<int64_t>(std::max(elements.size(), elements2.size()));
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std::unique_ptr<GCS> gcs;
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PSI_ASSERT_OK_AND_ASSIGN(
36-
gcs,
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GCS::Create(0.001, absl::MakeConstSpan(&elements[0], elements.size())));
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gcs, GCS::Create(0.001, max_inputs,
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absl::MakeConstSpan(&elements[0], elements.size())));
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39-
std::vector<std::string> elements2 = {"a", "b", "d", "e"};
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std::vector<int64_t> intersect = {0, 1, 2};
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auto res =
@@ -63,7 +65,7 @@ TEST(GCSTest, TestFPR) {
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std::unique_ptr<GCS> gcs;
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PSI_ASSERT_OK_AND_ASSIGN(
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gcs, GCS::Create(target_fpr,
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gcs, GCS::Create(target_fpr, (int64_t)elements.size(),
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absl::MakeConstSpan(&elements[0], elements.size())));
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// Test 10k elements to measure FPR.
@@ -98,8 +100,8 @@ TEST(GCSTest, TestToProtobuf) {
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std::unique_ptr<GCS> gcs;
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PSI_ASSERT_OK_AND_ASSIGN(
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gcs,
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GCS::Create(fpr, absl::MakeConstSpan(&elements[0], elements.size())));
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gcs, GCS::Create(fpr, (int64_t)elements.size(),
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absl::MakeConstSpan(&elements[0], elements.size())));
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// Create the protobuf from the GCS and check if it matches.
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psi_proto::ServerSetup encoded_gcs = gcs->ToProtobuf();
@@ -110,17 +112,19 @@ TEST(GCSTest, TestToProtobuf) {
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111113
TEST(GCSTest, TestCreateFromProtobuf) {
112114
std::vector<std::string> elements = {"a", "b", "c", "d"};
115+
std::vector<std::string> elements2 = {"a", "b", "c", "d", "not present"};
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auto max_inputs =
117+
static_cast<int64_t>(std::max(elements.size(), elements2.size()));
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114119
std::unique_ptr<GCS> gcs;
115120
PSI_ASSERT_OK_AND_ASSIGN(
116-
gcs,
117-
GCS::Create(0.001, absl::MakeConstSpan(&elements[0], elements.size())));
121+
gcs, GCS::Create(0.001, max_inputs,
122+
absl::MakeConstSpan(&elements[0], elements.size())));
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psi_proto::ServerSetup encoded_gcs = gcs->ToProtobuf();
120125
std::unique_ptr<GCS> gcs2;
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PSI_ASSERT_OK_AND_ASSIGN(gcs2, GCS::CreateFromProtobuf(encoded_gcs));
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123-
std::vector<std::string> elements2 = {"a", "b", "c", "d", "not present"};
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auto res =
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gcs2->Intersect(absl::MakeConstSpan(&elements2[0], elements2.size()));
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std::vector<int64_t> intersect = {0, 1, 2, 3};
@@ -149,7 +153,7 @@ TEST(GCSTest, TestGolombSize) {
149153
for (size_t i = 0; i < sizeof(fpr) / sizeof(double); i++) {
150154
std::unique_ptr<GCS> gcs;
151155
PSI_ASSERT_OK_AND_ASSIGN(
152-
gcs, GCS::Create(fpr[i],
156+
gcs, GCS::Create(fpr[i], (int64_t)elements.size(),
153157
absl::MakeConstSpan(&elements[0], elements.size())));
154158
auto res =
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gcs->Intersect(absl::MakeConstSpan(&elements[0], elements.size()));

‎private_set_intersection/cpp/psi_client_test.cpp‎

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@@ -55,7 +55,8 @@ class PsiClientTest : public ::testing::Test {
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// Insert server elements into GCS.
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PSI_ASSERT_OK_AND_ASSIGN(
5757
auto gcs,
58-
GCS::Create(fpr, absl::MakeConstSpan(&elements[0], elements.size())));
58+
GCS::Create(fpr, (int64_t)elements.size(),
59+
absl::MakeConstSpan(&elements[0], elements.size())));
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*server_setup = gcs->ToProtobuf();
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}
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‎private_set_intersection/cpp/psi_server.cpp‎

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Original file line numberDiff line numberDiff line change
@@ -77,7 +77,7 @@ StatusOr<psi_proto::ServerSetup> PsiServer::CreateSetupMessage(
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// Create a GCS and insert elements into it.
7878
ASSIGN_OR_RETURN(
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auto gcs,
80-
GCS::Create(corrected_fpr,
80+
GCS::Create(corrected_fpr, num_client_inputs,
8181
absl::MakeConstSpan(&encrypted[0], encrypted.size())));
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8383
// Return the GCS as a Protobuf
@@ -86,7 +86,7 @@ StatusOr<psi_proto::ServerSetup> PsiServer::CreateSetupMessage(
8686
// Create a Bloom Filter and insert elements into it.
8787
ASSIGN_OR_RETURN(auto filter,
8888
BloomFilter::Create(
89-
corrected_fpr,
89+
corrected_fpr, num_client_inputs,
9090
absl::MakeConstSpan(&encrypted[0], encrypted.size())));
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9292
// Return the Bloom Filter as a Protobuf

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