Composite Prime Moduli Sampling and Scaling Factor Calculations (#910 phase 2)

src/pke/include/cryptocontext.h

@@ -443,6 +443,20 @@ class CryptoContextImpl : public Serializable {
         return p;
     }
 
+    /**
+    * GetCompositeDegree: get composite degree of the current scheme crypto context.
+    * @return integer value corresponding to composite degree
+    */
+    uint32_t GetCompositeDegreeFromCtxt() const {
+        const auto cryptoParams = std::dynamic_pointer_cast<CryptoParametersRNS>(params);
+        if (!cryptoParams) {
+            std::string errorMsg(std::string("std::dynamic_pointer_cast<CryptoParametersRNS>() failed"));
+            OPENFHE_THROW(errorMsg);
+        }
+
+        return cryptoParams->GetCompositeDegree();
+    }
+
     PrivateKey<Element> privateKey;
 
 public:
@@ -1052,20 +1066,6 @@ class CryptoContextImpl : public Serializable {
         return params->GetElementParams()->GetRootOfUnity();
     }
 
-    /**
-    * GetCompositeDegree: get composite degree of the current scheme crypto context.
-    * @return integer value corresponding to composite degree
-    */
-    uint32_t GetCompositeDegreeFromCtxt() const {
-        const auto cryptoParams = std::dynamic_pointer_cast<CryptoParametersRNS>(params);
-        if (!cryptoParams) {
-            std::string errorMsg(std::string("std::dynamic_pointer_cast<CryptoParametersRNS>() failed"));
-            OPENFHE_THROW(errorMsg);
-        }
-
-        return cryptoParams->GetCompositeDegree();
-    }
-
     //------------------------------------------------------------------------------
     // KEYS GETTERS
     //------------------------------------------------------------------------------

src/pke/lib/scheme/ckksrns/ckksrns-advancedshe.cpp

@@ -48,24 +48,37 @@ namespace lbcrypto {
 
 Ciphertext<DCRTPoly> AdvancedSHECKKSRNS::EvalMultMany(const std::vector<Ciphertext<DCRTPoly>>& ciphertextVec,
                                                       const std::vector<EvalKey<DCRTPoly>>& evalKeys) const {
-    if (ciphertextVec.size() < 1)
+    const size_t inSize = ciphertextVec.size();
+
+    if (inSize < 2)
         OPENFHE_THROW("Input ciphertext vector size should be 1 or more");
 
-    const size_t inSize = ciphertextVec.size();
-    const size_t lim    = inSize * 2 - 2;
+    if (inSize == 1)
+        return ciphertextVec[0];
+
+    const size_t lim = inSize * 2 - 2;
     std::vector<Ciphertext<DCRTPoly>> ciphertextMultVec;
     ciphertextMultVec.resize(inSize - 1);
-    size_t ctrIndex = 0;
 
     auto algo               = ciphertextVec[0]->GetCryptoContext()->GetScheme();
-    const auto cc           = ciphertextVec[0]->GetCryptoContext();
     const auto cryptoParams = std::dynamic_pointer_cast<CryptoParametersRNS>(ciphertextVec[0]->GetCryptoParameters());
     uint32_t levelsToDrop   = cryptoParams->GetCompositeDegree();
 
-    for (size_t i = 0; i < lim; i = i + 2) {
-        ciphertextMultVec[ctrIndex] = algo->EvalMultAndRelinearize(
-            i < inSize ? ciphertextVec[i] : ciphertextMultVec[i - inSize],
-            i + 1 < inSize ? ciphertextVec[i + 1] : ciphertextMultVec[i + 1 - inSize], evalKeys);
+    size_t ctrIndex = 0;
+    size_t i        = 0;
+    for (; i < (inSize - 1); i += 2) {
+        ciphertextMultVec[ctrIndex] = algo->EvalMultAndRelinearize(ciphertextVec[i], ciphertextVec[(i + 1)], evalKeys);
+        algo->ModReduceInPlace(ciphertextMultVec[ctrIndex++], levelsToDrop);
+    }
+    if (i < inSize) {
+        ciphertextMultVec[ctrIndex] =
+            algo->EvalMultAndRelinearize(ciphertextVec[i], ciphertextMultVec[i + 1 - inSize], evalKeys);
+        algo->ModReduceInPlace(ciphertextMultVec[ctrIndex++], levelsToDrop);
+        i += 2;
+    }
+    for (; i < lim; i += 2) {
+        ciphertextMultVec[ctrIndex] =
+            algo->EvalMultAndRelinearize(ciphertextMultVec[i - inSize], ciphertextMultVec[i + 1 - inSize], evalKeys);
         algo->ModReduceInPlace(ciphertextMultVec[ctrIndex++], levelsToDrop);
     }
 

src/pke/lib/schemebase/base-advancedshe.cpp

@@ -46,9 +46,12 @@ template <class Element>
 Ciphertext<Element> AdvancedSHEBase<Element>::EvalAddMany(const std::vector<Ciphertext<Element>>& ciphertextVec) const {
     const size_t inSize = ciphertextVec.size();
 
-    if (ciphertextVec.size() < 1)
+    if (ciphertextVec.size() < 2)
         OPENFHE_THROW("Input ciphertext vector size should be 1 or more");
 
+    if (ciphertextVec.size() == 1)
+        return ciphertextVec[0];
+
     const size_t lim = inSize * 2 - 2;
     std::vector<Ciphertext<Element>> ciphertextSumVec;
     ciphertextSumVec.resize(inSize - 1);

src/pke/lib/schemerns/rns-leveledshe.cpp

@@ -540,16 +540,14 @@ void LeveledSHERNS::AdjustForMultInPlace(Ciphertext<DCRTPoly>& ciphertext1, Ciph
 Ciphertext<DCRTPoly> LeveledSHERNS::ComposedEvalMult(ConstCiphertext<DCRTPoly> ciphertext1,
                                                      ConstCiphertext<DCRTPoly> ciphertext2,
                                                      const EvalKey<DCRTPoly> evalKey) const {
-    const auto cc           = ciphertext1->GetCryptoContext();
     auto algo               = ciphertext1->GetCryptoContext()->GetScheme();
     const auto cryptoParams = std::dynamic_pointer_cast<CryptoParametersRNS>(ciphertext1->GetCryptoParameters());
     Ciphertext<DCRTPoly> ciphertext = EvalMult(ciphertext1, ciphertext2);
     algo->KeySwitchInPlace(ciphertext, evalKey);
     uint32_t levelsToDrop = BASE_NUM_LEVELS_TO_DROP;
     if (cryptoParams->GetScalingTechnique() == COMPOSITESCALINGAUTO ||
         cryptoParams->GetScalingTechnique() == COMPOSITESCALINGMANUAL) {
-        const auto cryptoRNSParams = std::dynamic_pointer_cast<CryptoParametersRNS>(cryptoParams);
-        levelsToDrop               = cryptoRNSParams->GetCompositeDegree();
+        levelsToDrop = cryptoParams->GetCompositeDegree();
     }
     ModReduceInPlace(ciphertext, levelsToDrop);
     return ciphertext;