      ECDSA_Verification_Operation(const ECDSA_PublicKey& ecdsa,
                                   const std::string& emsa) :
         PK_Ops::Verification_with_EMSA(emsa),
         m_group(ecdsa.domain()),
         m_gy_mul(m_group.get_base_point(), ecdsa.public_point())
         {
         }
      ECDSA_Verification_Operation(const ECDSA_PublicKey& ecdsa,
                                   const std::string& emsa) :
         PK_Ops::Verification_with_EMSA(emsa),
         m_group(ecdsa.domain()),
         m_gy_mul(m_group.get_base_point(), ecdsa.public_point())
         {
         }