xmss_hash.cpp

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/*
 * XMSS Hash
 * A collection of pseudorandom hash functions required for XMSS and WOTS
 * computations.
 * (C) 2016,2017 Matthias Gierlings
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 **/

#include <botan/xmss_hash.h>
#include <botan/exceptn.h>

namespace Botan {

XMSS_Hash::XMSS_Hash(const XMSS_Hash& hash)
   : XMSS_Hash(hash.m_hash_func_name)
   {
   }

XMSS_Hash::XMSS_Hash(const std::string& h_func_name) :
   m_hash(HashFunction::create(h_func_name)),
   m_hash_func_name(h_func_name)
   {
   if(!m_hash)
      throw Lookup_Error("XMSS cannot use hash " + h_func_name +
                         " because it is unavailable");

   m_output_length = m_hash->output_length();
   BOTAN_ASSERT(m_output_length > 0, "Hash output length of zero is invalid.");

   m_zero_padding.resize(m_output_length - 1);
   m_msg_hash.reset(m_hash->clone());
   }

void
XMSS_Hash::h(secure_vector<uint8_t>& result,
             const secure_vector<uint8_t>& key,
             const secure_vector<uint8_t>& data)
   {
   m_hash->update(m_zero_padding);
   m_hash->update(m_id_h);
   m_hash->update(key);
   m_hash->update(data);
   m_hash->final(result);
   }

void XMSS_Hash::h_msg_init(const secure_vector<uint8_t>& randomness,
                           const secure_vector<uint8_t>& root,
                           const secure_vector<uint8_t>& index_bytes)
   {
   m_msg_hash->clear();
   m_msg_hash->update(m_zero_padding);
   m_msg_hash->update(m_id_hmsg);
   m_msg_hash->update(randomness);
   m_msg_hash->update(root);
   m_msg_hash->update(index_bytes);
   }

void XMSS_Hash::h_msg_update(const uint8_t data[], size_t size)
   {
   m_msg_hash->update(data, size);
   }

secure_vector<uint8_t> XMSS_Hash::h_msg_final()
   {
   return m_msg_hash->final();
   }

secure_vector<uint8_t>
XMSS_Hash::h_msg(const secure_vector<uint8_t>& randomness,
                 const secure_vector<uint8_t>& root,
                 const secure_vector<uint8_t>& index_bytes,
                 const secure_vector<uint8_t>& data)
   {
   h_msg_init(randomness, root, index_bytes);
   m_msg_hash->update(data);
   return m_msg_hash->final();
   }

}