Botan::PSSR Class Reference

#include <pssr.h>

Inheritance diagram for Botan::PSSR:

Public Member Functions
AlgorithmIdentifier	config_for_x509 (const Private_Key &key, const std::string &cert_hash_name) const override
std::string	name () const override
std::unique_ptr< EMSA >	new_object () override
	PSSR (std::unique_ptr< HashFunction > hash)
	PSSR (std::unique_ptr< HashFunction > hash, size_t salt_size)
bool	requires_message_recovery () const override

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

Detailed Description

PSSR (called EMSA4 in IEEE 1363 and in old versions of the library)

Definition at line 19 of file pssr.h.

Constructor & Destructor Documentation

PSSR() [1/2]

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

explicit

Parameters

hash	the hash function to use

Definition at line 128 of file pssr.cpp.

                                           :
   m_hash(std::move(hash)),
   m_salt_size(m_hash->output_length()),
   m_required_salt_len(false)
   {
   }

PSSR() [2/2]

Botan::PSSR::PSSR	(	std::unique_ptr< HashFunction >	hash,
		size_t	salt_size
	)

Parameters

hash	the hash function to use
salt_size	the size of the salt to use in bytes

Definition at line 135 of file pssr.cpp.

                                                             :
   m_hash(std::move(hash)),
   m_salt_size(salt_size),
   m_required_salt_len(true)
   {
   }

Member Function Documentation

config_for_x509()

AlgorithmIdentifier Botan::PSSR::config_for_x509 ( const Private_Key &  key, const std::string &  cert_hash_name  ) const

overridevirtual

Prepare sig_algo for use in choose_sig_format for x509 certs

Parameters

key	used for checking compatibility with the encoding scheme
cert_hash_name	is checked to equal the hash for the encoding

Returns

algorithm identifier to signatures created using this key, padding method and hash.

Reimplemented from Botan::EMSA.

Definition at line 192 of file pssr.cpp.

   {
   if(cert_hash_name != m_hash->name())
      throw Invalid_Argument("Hash function from opts and hash_fn argument"
         " need to be identical");
   // check that the signature algorithm and the padding scheme fit
   if(!sig_algo_and_pad_ok(key.algo_name(), "EMSA4"))
      {
      throw Invalid_Argument("Encoding scheme with canonical name EMSA4"
         " not supported for signature algorithm " + key.algo_name());
      }
 
   const AlgorithmIdentifier hash_id(cert_hash_name, AlgorithmIdentifier::USE_NULL_PARAM);
   const AlgorithmIdentifier mgf_id("MGF1", hash_id.BER_encode());
 
   std::vector<uint8_t> parameters;
   DER_Encoder(parameters)
      .start_sequence()
      .start_context_specific(0).encode(hash_id).end_cons()
      .start_context_specific(1).encode(mgf_id).end_cons()
      .start_context_specific(2).encode(m_salt_size).end_cons()
      .start_context_specific(3).encode(size_t(1)).end_cons() // trailer field
      .end_cons();
 
   // hardcoded as RSA is the only valid algorithm for EMSA4 at the moment
   return AlgorithmIdentifier("RSA/EMSA4", parameters);
   }

References Botan::Public_Key::algo_name(), Botan::ASN1_Object::BER_encode(), Botan::DER_Encoder::encode(), Botan::DER_Encoder::end_cons(), Botan::sig_algo_and_pad_ok(), Botan::DER_Encoder::start_context_specific(), Botan::DER_Encoder::start_sequence(), and Botan::AlgorithmIdentifier::USE_NULL_PARAM.

create()

std::unique_ptr< EMSA > Botan::EMSA::create ( const std::string &  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 44 of file emsa.cpp.

   {
   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;
   }

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(), Botan::HashFunction::create(), hash, and salt_size.

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

create_or_throw()

std::unique_ptr< EMSA > Botan::EMSA::create_or_throw ( const std::string &  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 189 of file emsa.cpp.

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

References Botan::EMSA::create().

name()

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

overridevirtual

Returns

the SCAN name of the encoding/padding scheme

Implements Botan::EMSA.

Definition at line 187 of file pssr.cpp.

   {
   return "EMSA4(" + m_hash->name() + ",MGF1," + std::to_string(m_salt_size) + ")";
   }

References Botan::ASN1::to_string().

new_object()

std::unique_ptr< EMSA > Botan::PSSR::new_object ( )

overridevirtual

Returns

a new object representing the same encoding method as *this

Implements Botan::EMSA.

Definition at line 182 of file pssr.cpp.

   {
   return std::make_unique<PSSR>(m_hash->new_object(), m_salt_size);
   }

requires_message_recovery()

bool Botan::PSSR::requires_message_recovery ( ) const

inlineoverridevirtual

Return true if using this EMSA correctly requires a signature scheme with message recovery

Implements Botan::EMSA.

Definition at line 41 of file pssr.h.

{ return true; }

---

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

• src/lib/pk_pad/emsa_pssr/pssr.h
• src/lib/pk_pad/emsa_pssr/pssr.cpp