/*

* PKCS #1 v1.5 signature padding

* (C) 1999-2008 Jack Lloyd

*

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

*/

#include <botan/internal/emsa_pkcs1.h>

#include <botan/internal/hash_id.h>

#include <botan/exceptn.h>

#include <botan/pk_keys.h>

#include <botan/internal/padding.h>

namespace Botan {

namespace {

secure_vector<uint8_t> emsa3_encoding(const secure_vector<uint8_t>& msg,

                                   size_t output_bits,

                                   const uint8_t hash_id[],

                                   size_t hash_id_length)

   {

   size_t output_length = output_bits / 8;

   if(output_length < hash_id_length + msg.size() + 10)

      throw Encoding_Error("emsa3_encoding: Output length is too small");

   secure_vector<uint8_t> T(output_length);

   const size_t P_LENGTH = output_length - msg.size() - hash_id_length - 2;

   T[0] = 0x01;

   set_mem(&T[1], P_LENGTH, 0xFF);

   T[P_LENGTH+1] = 0x00;

   if(hash_id_length > 0)

      {

      BOTAN_ASSERT_NONNULL(hash_id);

      buffer_insert(T, P_LENGTH+2, hash_id, hash_id_length);

      }

   buffer_insert(T, output_length-msg.size(), msg.data(), msg.size());

   return T;

   }

}

void EMSA_PKCS1v15::update(const uint8_t input[], size_t length)

   {

   m_hash->update(input, length);

   }

secure_vector<uint8_t> EMSA_PKCS1v15::raw_data()

   {

   return m_hash->final();

   }

secure_vector<uint8_t>

EMSA_PKCS1v15::encoding_of(const secure_vector<uint8_t>& msg,

                           size_t output_bits,

                           RandomNumberGenerator& /*rng*/)

   {

   if(msg.size() != m_hash->output_length())

      throw Encoding_Error("EMSA_PKCS1v15::encoding_of: Bad input length");

   return emsa3_encoding(msg, output_bits,

                         m_hash_id.data(), m_hash_id.size());

   }

bool EMSA_PKCS1v15::verify(const secure_vector<uint8_t>& coded,

                           const secure_vector<uint8_t>& raw,

                           size_t key_bits)

   {

   if(raw.size() != m_hash->output_length())

      return false;

   try

      {

      return (coded == emsa3_encoding(raw, key_bits,

                                      m_hash_id.data(), m_hash_id.size()));

      }

   catch(...)

      {

      return false;

      }

   }

AlgorithmIdentifier EMSA_PKCS1v15::config_for_x509(const std::string& algo_name,

                                                   const std::string& cert_hash_name) const

   {

   if(cert_hash_name != m_hash->name())

      throw Invalid_Argument("PKCS1v15: Cert hash " + cert_hash_name +

                             " incompatible with specified hash " + m_hash->name());

   // check that the signature algorithm and the padding scheme fit

   if(!sig_algo_and_pad_ok(algo_name, "EMSA3"))

      {

      throw Invalid_Argument("Encoding scheme with canonical name EMSA3"

         " not supported for signature algorithm " + algo_name);

      }

   // for RSA PKCSv1.5 parameters "SHALL" be NULL

   const OID oid = OID::from_string(algo_name + "/" + name());

   return AlgorithmIdentifier(oid, AlgorithmIdentifier::USE_NULL_PARAM);

   }

EMSA_PKCS1v15::EMSA_PKCS1v15(std::unique_ptr<HashFunction> hash) :

   m_hash(std::move(hash))

   {

   m_hash_id = pkcs_hash_id(m_hash->name());

   }

EMSA_PKCS1v15_Raw::EMSA_PKCS1v15_Raw()

   {

   m_hash_output_len = 0;

   // m_hash_id, m_hash_name left empty

   }

EMSA_PKCS1v15_Raw::EMSA_PKCS1v15_Raw(const std::string& hash_algo)

   {

   std::unique_ptr<HashFunction> hash(HashFunction::create_or_throw(hash_algo));

   m_hash_id = pkcs_hash_id(hash_algo);

   m_hash_name = hash->name();

   m_hash_output_len = hash->output_length();

   }

void EMSA_PKCS1v15_Raw::update(const uint8_t input[], size_t length)

   {

   m_message += std::make_pair(input, length);

   }

secure_vector<uint8_t> EMSA_PKCS1v15_Raw::raw_data()

   {

   secure_vector<uint8_t> ret;

   std::swap(ret, m_message);

   if(m_hash_output_len > 0 && ret.size() != m_hash_output_len)

      throw Encoding_Error("EMSA_PKCS1v15_Raw::encoding_of: Bad input length");

   return ret;

   }

secure_vector<uint8_t>

EMSA_PKCS1v15_Raw::encoding_of(const secure_vector<uint8_t>& msg,

                               size_t output_bits,

                               RandomNumberGenerator& /*rng*/)

   {

   return emsa3_encoding(msg, output_bits, m_hash_id.data(), m_hash_id.size());

   }

bool EMSA_PKCS1v15_Raw::verify(const secure_vector<uint8_t>& coded,

                               const secure_vector<uint8_t>& raw,

                               size_t key_bits)

   {

   if(m_hash_output_len > 0 && raw.size() != m_hash_output_len)

      return false;

   try

      {

      return (coded == emsa3_encoding(raw, key_bits, m_hash_id.data(), m_hash_id.size()));

      }

   catch(...)

      {

      return false;

      }

   }

}