/*

* (C) 2015 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include <botan/internal/emsa.h>

#include <botan/hash.h>

#include <botan/internal/scan_name.h>

#include <botan/exceptn.h>

#if defined(BOTAN_HAS_EMSA1)

   #include <botan/internal/emsa1.h>

#endif

#if defined(BOTAN_HAS_EMSA_X931)

   #include <botan/internal/emsa_x931.h>

#endif

#if defined(BOTAN_HAS_EMSA_PKCS1)

   #include <botan/internal/emsa_pkcs1.h>

#endif

#if defined(BOTAN_HAS_EMSA_PSSR)

   #include <botan/internal/pssr.h>

#endif

#if defined(BOTAN_HAS_EMSA_RAW)

   #include <botan/internal/emsa_raw.h>

#endif

#if defined(BOTAN_HAS_ISO_9796)

   #include <botan/internal/iso9796.h>

#endif

namespace Botan {

AlgorithmIdentifier EMSA::config_for_x509(const Private_Key& /*unused*/,

                                          const std::string& /*unused*/) const

   {

   throw Not_Implemented("Encoding " + name() + " not supported for signing X509 objects");

   }

std::unique_ptr<EMSA> EMSA::create(const std::string& algo_spec)

   {

   SCAN_Name req(algo_spec);

#if defined(BOTAN_HAS_EMSA1)

   if(req.algo_name() == "EMSA1" && req.arg_count() == 1)

      {

      if(auto hash = HashFunction::create(req.arg(0)))

         return std::make_unique<EMSA1>(std::move(hash));

      }

#endif

#if defined(BOTAN_HAS_EMSA_PKCS1)

   if(req.algo_name() == "EMSA_PKCS1" ||

      req.algo_name() == "PKCS1v15" ||

      req.algo_name() == "EMSA-PKCS1-v1_5" ||

      req.algo_name() == "EMSA3")

      {

      if(req.arg_count() == 2 && req.arg(0) == "Raw")

         {

         return std::make_unique<EMSA_PKCS1v15_Raw>(req.arg(1));

         }

      else if(req.arg_count() == 1)

         {

         if(req.arg(0) == "Raw")

            {

            return std::make_unique<EMSA_PKCS1v15_Raw>();

            }

         else

            {

            if(auto hash = HashFunction::create(req.arg(0)))

               {

               return std::make_unique<EMSA_PKCS1v15>(std::move(hash));

               }

            }

         }

      }

#endif

#if defined(BOTAN_HAS_EMSA_PSSR)

   if(req.algo_name() == "PSS_Raw" ||

      req.algo_name() == "PSSR_Raw")

      {

      if(req.arg_count_between(1, 3) && req.arg(1, "MGF1") == "MGF1")

         {

         if(auto hash = HashFunction::create(req.arg(0)))

            {

            if(req.arg_count() == 3)

               {

               const size_t salt_size = req.arg_as_integer(2, 0);

               return std::make_unique<PSSR_Raw>(std::move(hash), salt_size);

               }

            else

               {

               return std::make_unique<PSSR_Raw>(std::move(hash));

               }

            }

         }

      }

   if(req.algo_name() == "PSS" ||

      req.algo_name() == "PSSR" ||

      req.algo_name() == "EMSA-PSS" ||

      req.algo_name() == "PSS-MGF1" ||

      req.algo_name() == "EMSA4")

      {

      if(req.arg_count_between(1, 3) && req.arg(1, "MGF1") == "MGF1")

         {

         if(auto hash = HashFunction::create(req.arg(0)))

            {

            if(req.arg_count() == 3)

               {

               const size_t salt_size = req.arg_as_integer(2, 0);

               return std::make_unique<PSSR>(std::move(hash), salt_size);

               }

            else

               {

               return std::make_unique<PSSR>(std::move(hash));

               }

            }

         }

      }

#endif

#if defined(BOTAN_HAS_ISO_9796)

   if(req.algo_name() == "ISO_9796_DS2")

      {

      if(req.arg_count_between(1, 3))

         {

         if(auto hash = HashFunction::create(req.arg(0)))

            {

            const size_t salt_size = req.arg_as_integer(2, hash->output_length());

            const bool implicit = req.arg(1, "exp") == "imp";

            return std::make_unique<ISO_9796_DS2>(std::move(hash), implicit, salt_size);

            }

         }

      }

   //ISO-9796-2 DS 3 is deterministic and DS2 without a salt

   if(req.algo_name() == "ISO_9796_DS3")

      {

      if(req.arg_count_between(1, 2))

         {

         if(auto hash = HashFunction::create(req.arg(0)))

            {

            const bool implicit = req.arg(1, "exp") == "imp";

            return std::make_unique<ISO_9796_DS3>(std::move(hash), implicit);

            }

         }

      }

#endif

#if defined(BOTAN_HAS_EMSA_X931)

   if(req.algo_name() == "EMSA_X931" ||

         req.algo_name() == "EMSA2" ||

         req.algo_name() == "X9.31")

      {

      if(req.arg_count() == 1)

         {

         if(auto hash = HashFunction::create(req.arg(0)))

            {

            return std::make_unique<EMSA_X931>(std::move(hash));

            }

         }

      }

#endif

#if defined(BOTAN_HAS_EMSA_RAW)

   if(req.algo_name() == "Raw")

      {

      if(req.arg_count() == 0)

         {

         return std::make_unique<EMSA_Raw>();

         }

      else

         {

         auto hash = HashFunction::create(req.arg(0));

         if(hash)

            return std::make_unique<EMSA_Raw>(hash->output_length());

         }

      }

#endif

   return nullptr;

   }

std::unique_ptr<EMSA> EMSA::create_or_throw(const std::string& algo_spec)

   {

   auto emsa = EMSA::create(algo_spec);

   if(emsa)

      return emsa;

   throw Algorithm_Not_Found(algo_spec);

   }

std::string hash_for_emsa(const std::string& algo_spec)

   {

   SCAN_Name emsa_name(algo_spec);

   if(emsa_name.arg_count() > 0)

      {

      return emsa_name.arg(0);

      }

   // If we don't understand what this is return a safe default

#if defined(BOTAN_HAS_SHA2_64)

   return "SHA-512";

#else

   return "SHA-256";

#endif

   }

}