Refactor ORAM code a bit to improve readability (#141)

Summary: Pull Request resolved: #141 As title Reviewed By: ashiquemfb Differential Revision: D35098605 fbshipit-source-id: 3acd932ffc1f5ae21bd4888b57095b07c5672922
facebookresearch · Mar 24, 2022 · 801c397 · 801c397
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commit 801c397
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Showing 4 changed files with 15 additions and 18 deletions.
diff --git a/fbpcf/mpc_std_lib/oram/DummyDifferenceCalculator_impl.h b/fbpcf/mpc_std_lib/oram/DummyDifferenceCalculator_impl.h
@@ -7,6 +7,7 @@
 
 #pragma once
 
+#include <stdexcept>
 #include "fbpcf/mpc_std_lib/util/util.h"
 
 namespace fbpcf::mpc_std_lib::oram::insecure {
@@ -61,7 +62,14 @@ DummyDifferenceCalculator<T, indicatorSumWidth>::calculateDifferenceBatch(
       subtrahend = subtrahendShares.at(i) - subtrahend;
 
       T minuend = util::Adapters<T>::convertFromBits(boolBuffer.at(i));
-      rst[i] = indicator * (minuend - subtrahend);
+      if (indicator == 1) {
+        rst[i] = minuend - subtrahend;
+      } else if (indicator == -1) {
+        rst[i] = subtrahend - minuend;
+      } else {
+        throw std::runtime_error("invalid indicator!");
+      }
+
     } else {
       agent_->sendSingleT(indicatorShares.at(i));
       agent_->sendSingleT(subtrahendShares.at(i));

diff --git a/fbpcf/mpc_std_lib/oram/WriteOnlyOram_impl.h b/fbpcf/mpc_std_lib/oram/WriteOnlyOram_impl.h
@@ -103,11 +103,12 @@ std::vector<std::vector<T>> WriteOnlyOram<T>::generateMasks(
 
   auto difference = calculator_->calculateDifferenceBatch(
       indicatorShares, values, subtrahendShares);
-
   for (size_t i = 0; i < batchSize; i++) {
     for (size_t j = 0; j < size_; j++) {
-      rst[i][j] =
-          rst[i][j] + indicatorKeyPairs.at(i).first.at(j) * difference.at(i);
+      bool indicator = indicatorKeyPairs.at(i).first.at(j);
+      if (indicator) {
+        rst[i][j] = rst[i][j] + difference.at(i);
+      }
     }
   }
   return rst;

diff --git a/fbpcf/mpc_std_lib/oram/test/WriteOnlyORAMTest.cpp b/fbpcf/mpc_std_lib/oram/test/WriteOnlyORAMTest.cpp
@@ -57,7 +57,7 @@ void testWriteOnlyOram(
     std::unique_ptr<IWriteOnlyOramFactory<T>> factory0,
     std::unique_ptr<IWriteOnlyOramFactory<T>> factory1,
     size_t oramSize) {
-  size_t batchSize = 16384;
+  size_t batchSize = oramSize * 30;
 
   auto [input0, input1, expectedValue] =
       util::generateRandomValuesToAdd<T>(oramSize, batchSize);
@@ -113,7 +113,7 @@ void runOramTestWithDummyComponents() {
           insecure::DummyDifferenceCalculatorFactory<T, indicatorSumWidth>>(
           false, 0, *factories[1]));
 
-  size_t oramSize = 150;
+  size_t oramSize = 10; // use a smaller number due to performance issue.
   testWriteOnlyOram<T>(std::move(factory0), std::move(factory1), oramSize);
 }
 

diff --git a/fbpcf/mpc_std_lib/util/aggregationValue_impl.h b/fbpcf/mpc_std_lib/util/aggregationValue_impl.h
@@ -54,18 +54,6 @@ inline AggregationValue operator-(const AggregationValue& v) {
   return AggregationValue{-v.conversionCount, -v.conversionValue};
 }
 
-inline AggregationValue operator*(int sign, const AggregationValue& v1) {
-  if (sign == 1) {
-    return v1;
-  } else if (sign == 0) {
-    return AggregationValue(0);
-  } else if (sign == -1) {
-    return -v1;
-  } else {
-    throw std::invalid_argument("can only multiply with -1, 0, 1");
-  }
-}
-
 inline void operator+=(AggregationValue& v1, const AggregationValue& v2) {
   v1.conversionCount += v2.conversionCount;
   v1.conversionValue += v2.conversionValue;