/*
 * XMSS Common Ops
 * (C) 2016,2017 Matthias Gierlings
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 **/

#ifndef BOTAN_XMSS_COMMON_OPS_H_
#define BOTAN_XMSS_COMMON_OPS_H_

#include <vector>
#include <botan/secmem.h>
#include <botan/xmss_parameters.h>
#include <botan/xmss_address.h>
#include <botan/xmss_hash.h>

//BOTAN_FUTURE_INTERNAL_HEADER(xmss_common_ops.h)

namespace Botan {

typedef std::vector<secure_vector<uint8_t>> wots_keysig_t;

/**
 * Operations shared by XMSS signature generation and verification operations.
 **/
class XMSS_Common_Ops
   {
   public:
      XMSS_Common_Ops(XMSS_Parameters::xmss_algorithm_t oid)
         : m_xmss_params(oid), m_hash(m_xmss_params.hash_function_name()) {}

   protected:
      /**
        * Algorithm 7: "RAND_HASH"
        *
        * Generates a randomized hash.
        *
        * This overload is used in multithreaded scenarios, where it is
        * required to provide seperate instances of XMSS_Hash to each
        * thread.
        *
        * @param[out] result The resulting randomized hash.
        * @param[in] left Left half of the hash function input.
        * @param[in] right Right half of the hash function input.
        * @param[in] adrs Adress of the hash function call.
        * @param[in] seed The seed for G.
        * @param[in] hash Instance of XMSS_Hash, that may only by the thead
        *            executing generate_public_key.
        **/
      void randomize_tree_hash(
         secure_vector<uint8_t>& result,
         const secure_vector<uint8_t>& left,
         const secure_vector<uint8_t>& right,
         XMSS_Address& adrs,
         const secure_vector<uint8_t>& seed,
         XMSS_Hash& hash);

      /**
        * Algorithm 7: "RAND_HASH"
        *
        * Generates a randomized hash.
        *
        * @param[out] result The resulting randomized hash.
        * @param[in] left Left half of the hash function input.
        * @param[in] right Right half of the hash function input.
        * @param[in] adrs Adress of the hash function call.
        * @param[in] seed The seed for G.
        **/
      inline void randomize_tree_hash(
         secure_vector<uint8_t>& result,
         const secure_vector<uint8_t>& left,
         const secure_vector<uint8_t>& right,
         XMSS_Address& adrs,
         const secure_vector<uint8_t>& seed)
         {
         randomize_tree_hash(result, left, right, adrs, seed, m_hash);
         }

      /**
       * Algorithm 8: "ltree"
       * Create an L-tree used to compute the leaves of the binary hash tree.
       * Takes a WOTS+ public key and compresses it to a single n-byte value.
       *
       * This overload is used in multithreaded scenarios, where it is
       * required to provide seperate instances of XMSS_Hash to each thread.
       *
       * @param[out] result Public key compressed to a single n-byte value
       *             pk[0].
       * @param[in] pk Winternitz One Time Signatures+ public key.
       * @param[in] adrs Address encoding the address of the L-Tree
       * @param[in] seed The seed generated during the public key generation.
       * @param[in] hash Instance of XMSS_Hash, that may only be used by the
       *            thead executing create_l_tree.
      **/
      void create_l_tree(secure_vector<uint8_t>& result,
                         wots_keysig_t pk,
                         XMSS_Address& adrs,
                         const secure_vector<uint8_t>& seed,
                         XMSS_Hash& hash);

      /**
       * Algorithm 8: "ltree"
       * Create an L-tree used to compute the leaves of the binary hash tree.
       * Takes a WOTS+ public key and compresses it to a single n-byte value.
       *
       * @param[out] result Public key compressed to a single n-byte value
       *             pk[0].
       * @param[in] pk Winternitz One Time Signatures+ public key.
       * @param[in] adrs Address encoding the address of the L-Tree
       * @param[in] seed The seed generated during the public key generation.
       **/
      inline void create_l_tree(secure_vector<uint8_t>& result,
                                wots_keysig_t pk,
                                XMSS_Address& adrs,
                                const secure_vector<uint8_t>& seed)
         {
         create_l_tree(result, pk, adrs, seed, m_hash);
         }

   protected:
      XMSS_Parameters m_xmss_params;
      XMSS_Hash m_hash;

   };

}

#endif
