From f1833f06f26d5d5bcd6772d78b6a4bcc9f13e445 Mon Sep 17 00:00:00 2001
From: "Mayeul@Zama" <mayeul.debellabre@zama.ai>
Date: Mon, 26 Sep 2022 14:54:49 +0200
Subject: [PATCH] feat(compiler): clarify input encryption noise variance

---
 .../Conversion/Utils/GlobalFHEContext.h          |  2 +-
 .../TFHEGlobalParametrization.cpp                |  2 +-
 compiler/lib/Support/V0ClientParameters.cpp      | 16 +++++++++-------
 3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/compiler/include/concretelang/Conversion/Utils/GlobalFHEContext.h b/compiler/include/concretelang/Conversion/Utils/GlobalFHEContext.h
index f312b830d..79a64baf8 100644
--- a/compiler/include/concretelang/Conversion/Utils/GlobalFHEContext.h
+++ b/compiler/include/concretelang/Conversion/Utils/GlobalFHEContext.h
@@ -66,7 +66,7 @@ struct V0Parameter {
   // TODO remove the shift when we have true polynomial size
   size_t getPolynomialSize() { return 1 << logPolynomialSize; }
 
-  size_t getNBigGlweDimension() { return glweDimension * getPolynomialSize(); }
+  size_t getNBigLweDimension() { return glweDimension * getPolynomialSize(); }
 };
 
 struct V0FHEContext {
diff --git a/compiler/lib/Conversion/TFHEGlobalParametrization/TFHEGlobalParametrization.cpp b/compiler/lib/Conversion/TFHEGlobalParametrization/TFHEGlobalParametrization.cpp
index e0fde7bbc..f7a232652 100644
--- a/compiler/lib/Conversion/TFHEGlobalParametrization/TFHEGlobalParametrization.cpp
+++ b/compiler/lib/Conversion/TFHEGlobalParametrization/TFHEGlobalParametrization.cpp
@@ -67,7 +67,7 @@ public:
 
   TFHE::GLWECipherTextType glweInterPBSType(GLWECipherTextType &type) {
     auto bits = 64;
-    auto dimension = cryptoParameters.getNBigGlweDimension();
+    auto dimension = cryptoParameters.getNBigLweDimension();
     auto polynomialSize = 1;
     auto precision = (signed)type.getP();
     auto crtDecomposition =
diff --git a/compiler/lib/Support/V0ClientParameters.cpp b/compiler/lib/Support/V0ClientParameters.cpp
index 728f27b07..5bd1b92b9 100644
--- a/compiler/lib/Support/V0ClientParameters.cpp
+++ b/compiler/lib/Support/V0ClientParameters.cpp
@@ -98,14 +98,16 @@ createClientParametersForV0(V0FHEContext fheContext,
                             llvm::StringRef functionName,
                             mlir::ModuleOp module) {
   auto v0Param = fheContext.parameter;
-  Variance encryptionVariance = v0Curve->getVariance(
+  Variance inputVariance =
+      v0Curve->getVariance(1, v0Param.getNBigLweDimension(), 64);
+
+  Variance bootstrapKeyVariance = v0Curve->getVariance(
       v0Param.glweDimension, v0Param.getPolynomialSize(), 64);
-  // Variance encryptionVariance = 0.;
-  Variance keyswitchVariance = v0Curve->getVariance(1, v0Param.nSmall, 64);
+  Variance keyswitchKeyVariance = v0Curve->getVariance(1, v0Param.nSmall, 64);
   // Static client parameters from global parameters for v0
   ClientParameters c;
   c.secretKeys = {
-      {clientlib::BIG_KEY, {/*.size = */ v0Param.getNBigGlweDimension()}},
+      {clientlib::BIG_KEY, {/*.size = */ v0Param.getNBigLweDimension()}},
   };
   bool has_small_key = v0Param.nSmall != 0;
   bool has_bootstrap = v0Param.brLevel != 0;
@@ -123,7 +125,7 @@ createClientParametersForV0(V0FHEContext fheContext,
                 /*.level = */ v0Param.brLevel,
                 /*.baseLog = */ v0Param.brLogBase,
                 /*.glweDimension = */ v0Param.glweDimension,
-                /*.variance = */ encryptionVariance,
+                /*.variance = */ bootstrapKeyVariance,
             },
         },
     };
@@ -137,7 +139,7 @@ createClientParametersForV0(V0FHEContext fheContext,
                 /*.outputSecretKeyID = */ clientlib::SMALL_KEY,
                 /*.level = */ v0Param.ksLevel,
                 /*.baseLog = */ v0Param.ksLogBase,
-                /*.variance = */ keyswitchVariance,
+                /*.variance = */ keyswitchKeyVariance,
             },
         },
     };
@@ -165,7 +167,7 @@ createClientParametersForV0(V0FHEContext fheContext,
           : inputs.back().isa<mlir::concretelang::Concrete::ContextType>();
 
   auto gateFromType = [&](mlir::Type ty) {
-    return gateFromMLIRType(clientlib::BIG_KEY, encryptionVariance, ty);
+    return gateFromMLIRType(clientlib::BIG_KEY, inputVariance, ty);
   };
   for (auto inType = funcType.getInputs().begin();
        inType < funcType.getInputs().end() - hasContext; inType++) {