/*

* (C) 2015 Jack Lloyd

*

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

*/

#include <botan/emsa.h>

#include <botan/hash.h>

#include <botan/scan_name.h>

#include <botan/exceptn.h>

#if defined(BOTAN_HAS_EMSA1)

   #include <botan/emsa1.h>

#endif

#if defined(BOTAN_HAS_EMSA_X931)

   #include <botan/emsa_x931.h>

#endif

#if defined(BOTAN_HAS_EMSA_PKCS1)

   #include <botan/emsa_pkcs1.h>

#endif

#if defined(BOTAN_HAS_EMSA_PSSR)

   #include <botan/pssr.h>

#endif

#if defined(BOTAN_HAS_EMSA_RAW)

   #include <botan/emsa_raw.h>

#endif

#if defined(BOTAN_HAS_ISO_9796)

   #include <botan/iso9796.h>

#endif

namespace Botan {

AlgorithmIdentifier EMSA::config_for_x509(const Private_Key&,

                                          const std::string&) const

   {

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

   }

EMSA* get_emsa(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 new EMSA1(hash.release());

      }

#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 new EMSA_PKCS1v15_Raw(req.arg(1));

         }

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

         {

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

            {

            return new EMSA_PKCS1v15_Raw;

            }

         else

            {

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

               {

               return new EMSA_PKCS1v15(hash.release());

               }

            }

         }

      }

#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 h = HashFunction::create(req.arg(0)))

            {

            if(req.arg_count() == 3)

               {

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

               return new PSSR_Raw(h.release(), salt_size);

               }

            else

               {

               return new PSSR_Raw(h.release());

               }

            }

         }

      }

   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 h = HashFunction::create(req.arg(0)))

            {

            if(req.arg_count() == 3)

               {

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

               return new PSSR(h.release(), salt_size);

               }

            else

               {

               return new PSSR(h.release());

               }

            }

         }

      }

#endif

#if defined(BOTAN_HAS_ISO_9796)

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

      {

      if(req.arg_count_between(1, 3))

         {

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

            {

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

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

            return new ISO_9796_DS2(h.release(), 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 h = HashFunction::create(req.arg(0)))

            {

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

            return new ISO_9796_DS3(h.release(), 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 new EMSA_X931(hash.release());

            }

         }

      }

#endif

#if defined(BOTAN_HAS_EMSA_RAW)

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

      {

      if(req.arg_count() == 0)

         {

         return new EMSA_Raw;

         }

      else

         {

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

         if(hash)

            return new EMSA_Raw(hash->output_length());

         }

      }

#endif

   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)

      {

      const std::string pos_hash = emsa_name.arg(0);

      return pos_hash;

      }

   // 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

   }

}