1 files changed, 33 insertions, 0 deletions
diff --git a/private_join_and_compute/crypto/two_modulus_crt.cc b/private_join_and_compute/crypto/two_modulus_crt.cc
new file mode 100644
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+++ b/private_join_and_compute/crypto/two_modulus_crt.cc
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+/*
+ * Copyright 2019 Google Inc.
+ * 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 "private_join_and_compute/crypto/two_modulus_crt.h"
+
+namespace private_join_and_compute {
+
+TwoModulusCrt::TwoModulusCrt(const BigNum& coprime1, const BigNum& coprime2)
+    : crt_term1_(coprime2 * coprime2.ModInverse(coprime1)),
+      crt_term2_(coprime1 * coprime1.ModInverse(coprime2)),
+      coprime_product_(coprime1 * coprime2) {}
+
+BigNum TwoModulusCrt::Compute(const BigNum& solution1,
+                              const BigNum& solution2) const {
+  return ((solution1 * crt_term1_) + (solution2 * crt_term2_))
+      .Mod(coprime_product_);
+}
+
+BigNum TwoModulusCrt::GetCoprimeProduct() const { return coprime_product_; }
+
+}  // namespace private_join_and_compute