Botan::EMSA_X931 Class Reference

#include <emsa_x931.h>

Inheritance diagram for Botan::EMSA_X931:

Public Member Functions
	EMSA_X931 (std::unique_ptr< HashFunction > hash)
std::string	hash_function () const override
std::string	name () const override

Static Public Member Functions
static std::unique_ptr< EMSA >	create (std::string_view algo_spec)
static std::unique_ptr< EMSA >	create_or_throw (std::string_view algo_spec)

Detailed Description

EMSA from X9.31 (EMSA2 in IEEE 1363) Useful for Rabin-Williams, also sometimes used with RSA in odd protocols.

Definition at line 21 of file emsa_x931.h.

Constructor & Destructor Documentation

EMSA_X931()

Botan::EMSA_X931::EMSA_X931 ( std::unique_ptr< HashFunction > hash )

explicit

Parameters

hash	the hash function to use

Definition at line 86 of file emsa_x931.cpp.

                                                     : m_hash(std::move(hash)) {
   m_empty_hash = m_hash->final_stdvec();
 
   m_hash_id = ieee1363_hash_id(m_hash->name());
 
   if(!m_hash_id) {
      throw Encoding_Error("EMSA_X931 no hash identifier for " + m_hash->name());
   }
}

References Botan::ieee1363_hash_id().

Member Function Documentation

create()

std::unique_ptr< EMSA > Botan::EMSA::create ( std::string_view algo_spec )

staticinherited

Factory method for EMSA (message-encoding methods for signatures with appendix) objects

Parameters

algo_spec

the name of the EMSA to create

Returns

pointer to newly allocated object of that type, or nullptr

Definition at line 35 of file emsa.cpp.

                                                         {
   SCAN_Name req(algo_spec);
 
#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;
}

References Botan::SCAN_Name::algo_name(), Botan::SCAN_Name::arg(), Botan::SCAN_Name::arg_as_integer(), Botan::SCAN_Name::arg_count(), Botan::SCAN_Name::arg_count_between(), and Botan::HashFunction::create().

Referenced by Botan::EMSA::create_or_throw().

create_or_throw()

std::unique_ptr< EMSA > Botan::EMSA::create_or_throw ( std::string_view algo_spec )

staticinherited

Factory method for EMSA (message-encoding methods for signatures with appendix) objects

Parameters

algo_spec

the name of the EMSA to create

Returns

pointer to newly allocated object of that type, or throws

Definition at line 131 of file emsa.cpp.

                                                                  {
   auto emsa = EMSA::create(algo_spec);
   if(emsa) {
      return emsa;
   }
   throw Algorithm_Not_Found(algo_spec);
}

References Botan::EMSA::create().

hash_function()

std::string Botan::EMSA_X931::hash_function ( ) const

inlineoverridevirtual

Return the hash function being used by this padding scheme

Implements Botan::EMSA.

Definition at line 30 of file emsa_x931.h.

{ return m_hash->name(); }

name()

std::string Botan::EMSA_X931::name ( ) const

overridevirtual

Returns

the SCAN name of the encoding/padding scheme

Implements Botan::EMSA.

Definition at line 51 of file emsa_x931.cpp.

                                {
   return "EMSA2(" + m_hash->name() + ")";
}

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The documentation for this class was generated from the following files:

• src/lib/pk_pad/emsa_x931/emsa_x931.h
• src/lib/pk_pad/emsa_x931/emsa_x931.cpp