Botan::PSSR Class Reference

#include <pssr.h>

Inheritance diagram for Botan::PSSR:

Public Member Functions
EMSA *	clone () override
AlgorithmIdentifier	config_for_x509 (const Private_Key &key, const std::string &cert_hash_name) const override
std::string	name () const override
	PSSR (HashFunction *hash)
	PSSR (HashFunction *hash, size_t salt_size)

Detailed Description

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

Definition at line 21 of file pssr.h.

Constructor & Destructor Documentation

PSSR() [1/2]

Botan::PSSR::PSSR ( HashFunction *  hash )

explicit

Parameters

hash	the hash function to use

Definition at line 128 of file pssr.cpp.

                          :
   m_hash(h),
   m_salt_size(m_hash->output_length()),
   m_required_salt_len(false)
   {
   }

Referenced by clone().

PSSR() [2/2]

Botan::PSSR::PSSR	(	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(h),
   m_salt_size(salt_size),
   m_required_salt_len(true)
   {
   }

Member Function Documentation

clone()

EMSA * Botan::PSSR::clone ( )

overridevirtual

Returns

a new object representing the same encoding method as *this

Implements Botan::EMSA.

Definition at line 182 of file pssr.cpp.

   {
   return new PSSR(m_hash->clone(), m_salt_size);
   }

References PSSR().

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_cons(SEQUENCE)
      .start_cons(ASN1_Tag(0), CONTEXT_SPECIFIC).encode(hash_id).end_cons()
      .start_cons(ASN1_Tag(1), CONTEXT_SPECIFIC).encode(mgf_id).end_cons()
      .start_cons(ASN1_Tag(2), CONTEXT_SPECIFIC).encode(m_salt_size).end_cons()
      .start_cons(ASN1_Tag(3), CONTEXT_SPECIFIC).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::CONTEXT_SPECIFIC, Botan::DER_Encoder::encode(), Botan::DER_Encoder::end_cons(), Botan::SEQUENCE, Botan::sig_algo_and_pad_ok(), Botan::DER_Encoder::start_cons(), and Botan::AlgorithmIdentifier::USE_NULL_PARAM.

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().

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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