added ring dimension validators for BGV, BFV, and CKKS

openfheorg · Jun 11, 2024 · fbddde9 · fbddde9
1 parent e2f0a91
commit fbddde9
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Showing 4 changed files with 69 additions and 2 deletions.
diff --git a/src/pke/lib/scheme/bfvrns/bfvrns-parametergeneration.cpp b/src/pke/lib/scheme/bfvrns/bfvrns-parametergeneration.cpp
@@ -373,6 +373,27 @@ bool ParameterGenerationBFVRNS::ParamsGenBFVRNS(std::shared_ptr<CryptoParameters
 
     cryptoParamsBFVRNS->PrecomputeCRTTables(ksTech, scalTech, encTech, multTech, numPartQ, auxBits, 0);
 
+    // Validate the ring dimension found using estimated logQ(P) against actual logQ(P)
+    if (stdLevel != HEStd_NotSet) {
+        uint32_t logActualQ = 0;
+        if (ksTech == HYBRID) {
+            logActualQ = cryptoParamsBFVRNS->GetParamsQP()->GetModulus().GetMSB();
+        }
+        else {
+            logActualQ = cryptoParamsBFVRNS->GetElementParams()->GetModulus().GetMSB();
+        }
+
+        uint32_t nActual = StdLatticeParm::FindRingDim(distType, stdLevel, logActualQ);
+        if (n < nActual) {
+            std::string errMsg("The ring dimension found using estimated logQ(P) [");
+            errMsg += std::to_string(n) + "] does does not meet security requirements. ";
+            errMsg += "Report this problem to OpenFHE developers and set the ring dimension manually to ";
+            errMsg += std::to_string(nActual) + ".";
+
+            OPENFHE_THROW(errMsg);
+        }
+    }
+
     return true;
 }
 

diff --git a/src/pke/lib/scheme/bgvrns/bgvrns-parametergeneration.cpp b/src/pke/lib/scheme/bgvrns/bgvrns-parametergeneration.cpp
@@ -608,6 +608,31 @@ bool ParameterGenerationBGVRNS::ParamsGenBGVRNS(std::shared_ptr<CryptoParameters
         cryptoParamsBGVRNS->SetEncodingParams(encodingParamsNew);
     }
     cryptoParamsBGVRNS->PrecomputeCRTTables(ksTech, scalTech, encTech, multTech, numPartQ, auxBits, 0);
+
+    // Validate the ring dimension found using estimated logQ(P) against actual logQ(P)
+    SecurityLevel stdLevel = cryptoParamsBGVRNS->GetStdLevel();
+    if (stdLevel != HEStd_NotSet) {
+        uint32_t logActualQ = 0;
+        if (ksTech == HYBRID) {
+            logActualQ = cryptoParamsBGVRNS->GetParamsQP()->GetModulus().GetMSB();
+        }
+        else {
+            logActualQ = cryptoParamsBGVRNS->GetElementParams()->GetModulus().GetMSB();
+        }
+
+        DistributionType distType = (cryptoParamsBGVRNS->GetSecretKeyDist() == GAUSSIAN) ? HEStd_error : HEStd_ternary;
+        uint32_t nActual          = StdLatticeParm::FindRingDim(distType, stdLevel, logActualQ);
+
+        if (n < nActual) {
+            std::string errMsg("The ring dimension found using estimated logQ(P) [");
+            errMsg += std::to_string(n) + "] does does not meet security requirements. ";
+            errMsg += "Report this problem to OpenFHE developers and set the ring dimension manually to ";
+            errMsg += std::to_string(nActual) + ".";
+
+            OPENFHE_THROW(errMsg);
+        }
+    }
+
     return true;
 }
 

diff --git a/src/pke/lib/scheme/ckksrns/ckksrns-parametergeneration.cpp b/src/pke/lib/scheme/ckksrns/ckksrns-parametergeneration.cpp
@@ -235,6 +235,27 @@ bool ParameterGenerationCKKSRNS::ParamsGenCKKSRNS(std::shared_ptr<CryptoParamete
 
     cryptoParamsCKKSRNS->PrecomputeCRTTables(ksTech, scalTech, encTech, multTech, numPartQ, auxBits, extraModSize);
 
+    // Validate the ring dimension found using estimated logQ(P) against actual logQ(P)
+    if (stdLevel != HEStd_NotSet) {
+        uint32_t logActualQ = 0;
+        if (ksTech == HYBRID) {
+            logActualQ = cryptoParamsCKKSRNS->GetParamsQP()->GetModulus().GetMSB();
+        }
+        else {
+            logActualQ = cryptoParamsCKKSRNS->GetElementParams()->GetModulus().GetMSB();
+        }
+
+        uint32_t nActual = StdLatticeParm::FindRingDim(distType, stdLevel, logActualQ);
+        if (n < nActual) {
+            std::string errMsg("The ring dimension found using estimated logQ(P) [");
+            errMsg += std::to_string(n) + "] does does not meet security requirements. ";
+            errMsg += "Report this problem to OpenFHE developers and set the ring dimension manually to ";
+            errMsg += std::to_string(nActual) + ".";
+
+            OPENFHE_THROW(errMsg);
+        }
+    }
+
     return true;
 }
 

diff --git a/src/pke/lib/schemerns/rns-cryptoparameters.cpp b/src/pke/lib/schemerns/rns-cryptoparameters.cpp
@@ -395,9 +395,9 @@ std::pair<double, uint32_t> CryptoParametersRNS::EstimateLogP(uint32_t numPartQ,
     if (extraModulusSize > 0)
         sizeQ++;
 
-    // Compute ceil(sizeQ/m_numPartQ), the # of towers per digit
+    // Compute ceil(sizeQ/numPartQ), the # of towers per digit
     uint32_t numPerPartQ = ceil(static_cast<double>(sizeQ) / numPartQ);
-    if ((int32_t)(sizeQ - numPerPartQ * (numPartQ - 1)) <= 0) {
+    if ((uint32_t)(sizeQ - numPerPartQ * (numPartQ - 1)) <= 0) {
         auto str =
             "CryptoParametersRNS::EstimateLogP - HYBRID key "
             "switching parameters: Can't appropriately distribute " +