Updates to v1.6.1

CMakeLists.txt

@@ -29,7 +29,7 @@ project (OpenFHE C CXX)
 
 set(OPENFHE_VERSION_MAJOR 1)
 set(OPENFHE_VERSION_MINOR 6)
-set(OPENFHE_VERSION_PATCH 0)
+set(OPENFHE_VERSION_PATCH 1)
 set(OPENFHE_VERSION ${OPENFHE_VERSION_MAJOR}.${OPENFHE_VERSION_MINOR}.${OPENFHE_VERSION_PATCH})
 
 set(CMAKE_CXX_STANDARD 17)

docs/static_docs/Release_Notes.md

@@ -1,3 +1,9 @@
+10/09/2026: OpenFHE 1.6.1 (stable) is released
+
+* Fixes decryption failures after CKKS bootstrapping with uniform ternary secrets for affected scenarios (#1364)
+
+The detailed list of changes is available at https://github.com/openfheorg/openfhe-development/issues?q=is%3Aissue+milestone%3A%22Release+1.6.1%22
+
 09/28/2026: OpenFHE 1.6.0 (development) is released
 
 * Adds the CKKS-based Fourier-extension functional bootstrapping method proposed in https://ia.cr/2026/367 and presented at EUROCRYPT '26 (#1207)

src/pke/include/scheme/ckksrns/ckksrns-fhe.h

@@ -54,6 +54,8 @@
  */
 namespace lbcrypto {
 
+class CryptoParametersCKKSRNS;
+
 /**
  * @brief Precomputations of CKKS bootstrapping for one number of slots.
  *
@@ -111,6 +113,13 @@ class CKKSBootstrapPrecom {
     /// flag indicating whether we perform StC before ModRaise
     bool BTSlotsEncoding;
 
+    // which setup populated this precomputation. Each bootstrapping variant folds its own uniform-secret overflow bound
+    // K (K_UNIFORM, K_UNIFORM_FBT or K_UNIFORM_FEFBT) into the CoeffsToSlots matrix, so a precomputation generated by
+    // one variant cannot be consumed by another. Not serialized: only the parameters are serialized, and the setup call
+    // that rebuilds the matrices after deserialization restores the variant together with them.
+    enum BootstrapVariant : uint32_t { BOOTSTRAP = 0, FBT = 1, FEFBT = 2 };
+    BootstrapVariant m_variant = BOOTSTRAP;
+
     template <class Archive>
     void save(Archive& ar) const {
         ar(cereal::make_nvp("dim1_Enc", m_paramsEnc.g));
@@ -998,6 +1007,21 @@ class FHECKKSRNS : public FHERNS {
         OPENFHE_THROW("Precomputations for " + std::to_string(slots) + " slots not found.");
     }
 
+    // The bootstrapping variants fold different uniform-secret overflow bounds K into the
+    // CoeffsToSlots matrix (K_UNIFORM, K_UNIFORM_FBT, K_UNIFORM_FEFBT), so a precomputation can
+    // only be consumed by the variant whose setup generated it.
+    CKKSBootstrapPrecom& GetBootPrecom(uint32_t slots, CKKSBootstrapPrecom::BootstrapVariant variant) const {
+        auto& precom = GetBootPrecom(slots);
+        if (precom.m_variant != variant) {
+            constexpr const char* setupName[] = {"EvalBootstrapSetup", "EvalFBTSetup", "EvalFEFuncBootstrapSetup"};
+            OPENFHE_THROW("The bootstrapping precomputation for " + std::to_string(slots) + " slots was generated by " +
+                          setupName[precom.m_variant] + ", but this operation requires " + setupName[variant] +
+                          ": regular, functional and FE functional bootstrapping fold different overflow bounds K "
+                          "into the CoeffsToSlots matrix and cannot share precomputations.");
+        }
+        return precom;
+    }
+
     //------------------------------------------------------------------------------
     // Find Rotation Indices
     //------------------------------------------------------------------------------
@@ -1127,6 +1151,23 @@ class FHECKKSRNS : public FHERNS {
     static constexpr uint32_t K_UNIFORM = 648;
     static constexpr uint32_t K_UNIFORM_FBT = 672;
     static constexpr uint32_t K_UNIFORM_FEFBT = 696;
+
+    /**
+     * Returns the mod-raise overflow bound K for the secret key distribution of cryptoParams. Every setup
+     * folds K into the CoeffsToSlots matrix (the scaleEnc factor): the matrix coefficients carry 1/K at
+     * full precision, whereas the runtime scalar 2^-deg/(K*N) would be truncated to
+     * log2(scalingFactor) - log2(K*N) - deg bits when encoded at the scaling factor (about 19 bits for a
+     * 50-bit scaling factor and a 60-bit first modulus at N = 2^12, and 4 bits fewer at N = 2^16), an
+     * error that the overflow I (up to K) and the correction factor then amplify. Folding also keeps the
+     * CtS rotations acting on the full-magnitude message, so their key-switching noise is not amplified.
+     *
+     * @param cryptoParams the CKKS crypto parameters
+     * @param uniformK the bound for UNIFORM_TERNARY, specific to the bootstrapping variant: K_UNIFORM for
+     *   regular, K_UNIFORM_FBT for functional and K_UNIFORM_FEFBT for FE functional bootstrapping
+     * @return the overflow bound K
+     */
+    static double GetModRaiseOverflowBound(const std::shared_ptr<CryptoParametersCKKSRNS>& cryptoParams,
+                                           double uniformK);
     // number of double-angle iterations in CKKS bootstrapping. Must be static because it is used in a static function.
     static constexpr uint32_t R_UNIFORM = 6;
     // number of double-angle iterations in CKKS bootstrapping. Must be static because it is used in a static function.