Create an overload for IntMPBootRandomElementGen() taking Ciphertext instead of PublicKey

src/pke/include/cryptocontext.h

@@ -3412,6 +3412,14 @@ class CryptoContextImpl : public Serializable {
     * @return Random ring element as ciphertext.
     */
     Ciphertext<Element> IntMPBootRandomElementGen(const PublicKey<Element> publicKey) const;
+    /**
+    * @brief Generates a common random polynomial for Multi-Party Interactive Bootstrapping (Threshold FHE)
+    *        using an existing ciphertext, eliminating the need to supply a public key explicitly
+    *
+    * @param ciphertext Reference ciphertext used to derive the cryptocontext and parameters.
+    * @return Random ring element as ciphertext.
+    */
+    Ciphertext<Element> IntMPBootRandomElementGen(ConstCiphertext<Element>& ciphertext) const;
 
     /**
     * @brief Performs masked decryption as part of Multi-Party Interactive Bootstrapping (Threshold FHE).

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

@@ -61,6 +61,9 @@ class MultipartyCKKSRNS : public MultipartyRNS {
     Ciphertext<DCRTPoly> IntMPBootRandomElementGen(std::shared_ptr<CryptoParametersCKKSRNS> params,
                                                    const PublicKey<DCRTPoly> publicKey) const override;
 
+    Ciphertext<DCRTPoly> IntMPBootRandomElementGen(std::shared_ptr<CryptoParametersCKKSRNS> params,
+                                                   ConstCiphertext<DCRTPoly>& ciphertext) const override;
+
     std::vector<Ciphertext<DCRTPoly>> IntMPBootDecrypt(const PrivateKey<DCRTPoly> privateKey,
                                                        ConstCiphertext<DCRTPoly> ciphertext,
                                                        ConstCiphertext<DCRTPoly> a) const override;

src/pke/include/schemebase/base-multiparty.h

@@ -367,6 +367,10 @@ class MultipartyBase {
                                                           const PublicKey<Element> publicKey) const {
         OPENFHE_THROW(NOT_SUPPORTED_ERROR);
     }
+    virtual Ciphertext<Element> IntMPBootRandomElementGen(std::shared_ptr<CryptoParametersCKKSRNS> params,
+                                                          ConstCiphertext<Element>& ciphertext) const {
+        OPENFHE_THROW(NOT_SUPPORTED_ERROR);
+    }
 
     /**
     * Threshold FHE: Does masked decryption as part of Multi-Party Interactive Bootstrapping.

src/pke/include/schemebase/base-scheme.h

@@ -1110,6 +1110,12 @@ class SchemeBase {
         return m_Multiparty->IntMPBootRandomElementGen(cryptoParameters, publicKey);
     }
 
+    Ciphertext<Element> IntMPBootRandomElementGen(std::shared_ptr<CryptoParametersCKKSRNS> cryptoParameters,
+                                                  ConstCiphertext<Element>& ciphertext) const {
+        VerifyMultipartyEnabled(__func__);
+        return m_Multiparty->IntMPBootRandomElementGen(cryptoParameters, ciphertext);
+    }
+
     std::vector<Ciphertext<Element>> IntMPBootDecrypt(const PrivateKey<Element> privateKey,
                                                       ConstCiphertext<Element> ciphertext,
                                                       ConstCiphertext<Element> a) const {

src/pke/lib/cryptocontext.cpp

@@ -658,9 +658,21 @@ Ciphertext<Element> CryptoContextImpl<Element>::IntMPBootAdjustScale(ConstCipher
 template <typename Element>
 Ciphertext<Element> CryptoContextImpl<Element>::IntMPBootRandomElementGen(const PublicKey<Element> publicKey) const {
     const auto cryptoParamsCKKS = std::dynamic_pointer_cast<CryptoParametersCKKSRNS>(this->GetCryptoParameters());
+    if (cryptoParamsCKKS == nullptr)
+        OPENFHE_THROW("The parameter object is not of the CryptoParametersCKKSRNS type");
+
     return GetScheme()->IntMPBootRandomElementGen(cryptoParamsCKKS, publicKey);
 }
 
+template <typename Element>
+Ciphertext<Element> CryptoContextImpl<Element>::IntMPBootRandomElementGen(ConstCiphertext<Element>& ciphertext) const {
+    const auto cryptoParamsCKKS = std::dynamic_pointer_cast<CryptoParametersCKKSRNS>(ciphertext->GetCryptoParameters());
+    if (cryptoParamsCKKS == nullptr)
+        OPENFHE_THROW("The parameter object is not of the CryptoParametersCKKSRNS type");
+
+    return GetScheme()->IntMPBootRandomElementGen(cryptoParamsCKKS, ciphertext);
+}
+
 template <typename Element>
 std::vector<Ciphertext<Element>> CryptoContextImpl<Element>::IntMPBootDecrypt(const PrivateKey<Element> privateKey,
                                                                               ConstCiphertext<Element>& ciphertext,

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

@@ -159,9 +159,8 @@ Ciphertext<DCRTPoly> MultipartyCKKSRNS::IntMPBootAdjustScale(ConstCiphertext<DCR
 
 Ciphertext<DCRTPoly> MultipartyCKKSRNS::IntMPBootRandomElementGen(std::shared_ptr<CryptoParametersCKKSRNS> params,
                                                                   const PublicKey<DCRTPoly> publicKey) const {
-    auto ildcrtparams = params->GetElementParams();
     typename DCRTPoly::DugType dug;
-    DCRTPoly crp(dug, ildcrtparams);
+    DCRTPoly crp(dug, params->GetElementParams());
     crp.SetFormat(Format::EVALUATION);
 
     Ciphertext<DCRTPoly> outCtxt(std::make_shared<CiphertextImpl<DCRTPoly>>(publicKey));
@@ -170,6 +169,20 @@ Ciphertext<DCRTPoly> MultipartyCKKSRNS::IntMPBootRandomElementGen(std::shared_pt
     return outCtxt;
 }
 
+Ciphertext<DCRTPoly> MultipartyCKKSRNS::IntMPBootRandomElementGen(std::shared_ptr<CryptoParametersCKKSRNS> params,
+                                                                  ConstCiphertext<DCRTPoly>& ciphertext) const {
+    const auto& ctxtElems = ciphertext->GetElements();
+
+    typename DCRTPoly::DugType dug;
+    DCRTPoly crp(dug, ctxtElems[0].GetParams());
+    crp.SetFormat(Format::EVALUATION);
+
+    Ciphertext<DCRTPoly> outCtxt(std::make_shared<CiphertextImpl<DCRTPoly>>(*ciphertext));
+
+    outCtxt->SetElements({std::move(crp)});
+    return outCtxt;
+}
+
 // Subroutines for Interactive Multi-Party Bootstrapping
 // Calculating RNS parameters
 void PrecomputeRNSExtensionTables(CryptoContext<DCRTPoly>& cc, usint from, usint to, RNSExtensionTables& rnsExtTables) {