/*

 * ISO-9796-2 - Digital signature schemes giving message recovery schemes 2 and 3

 * (C) 2016 Tobias Niemann, Hackmanit GmbH

 *

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

 */

#ifndef BOTAN_ISO9796_H_

#define BOTAN_ISO9796_H_

#include <botan/hash.h>

#include <botan/internal/emsa.h>

namespace Botan {

/**

* ISO-9796-2 - Digital signature scheme 2 (probabilistic)

*/

class ISO_9796_DS2 final : public EMSA {

   public:

      /**

       * @param hash function to use

       * @param implicit whether or not the trailer is implicit

       */

      explicit ISO_9796_DS2(std::unique_ptr<HashFunction> hash, bool implicit = false) :

            m_hash(std::move(hash)), m_implicit(implicit), m_salt_len(hash->output_length()) {}

      /**

       * @param hash function to use

       * @param implicit whether or not the trailer is implicit

       * @param salt_size size of the salt to use in bytes

       */

      ISO_9796_DS2(std::unique_ptr<HashFunction> hash, bool implicit, size_t salt_size) :

            m_hash(std::move(hash)), m_implicit(implicit), m_salt_len(salt_size) {}

      std::string hash_function() const override { return m_hash->name(); }

      std::string name() const override;

   private:

      void update(const uint8_t input[], size_t length) override;

      std::vector<uint8_t> raw_data() override;

      std::vector<uint8_t> encoding_of(std::span<const uint8_t> msg,

                                       size_t output_bits,

                                       RandomNumberGenerator& rng) override;

      bool verify(std::span<const uint8_t> coded, std::span<const uint8_t> raw, size_t key_bits) override;

      std::unique_ptr<HashFunction> m_hash;

      bool m_implicit;

      size_t m_salt_len;

      std::vector<uint8_t> m_msg_buffer;

};

/**

* ISO-9796-2 - Digital signature scheme 3 (deterministic)

*/

class ISO_9796_DS3 final : public EMSA {

   public:

      /**

       * @param hash function to use

       * @param implicit whether or not the trailer is implicit

       */

      ISO_9796_DS3(std::unique_ptr<HashFunction> hash, bool implicit = false) :

            m_hash(std::move(hash)), m_implicit(implicit) {}

      std::string name() const override;

      std::string hash_function() const override { return m_hash->name(); }

   private:

      void update(const uint8_t input[], size_t length) override;

      std::vector<uint8_t> raw_data() override;

      std::vector<uint8_t> encoding_of(std::span<const uint8_t> msg,

                                       size_t output_bits,

                                       RandomNumberGenerator& rng) override;

      bool verify(std::span<const uint8_t> coded, std::span<const uint8_t> raw, size_t key_bits) override;

      std::unique_ptr<HashFunction> m_hash;

      bool m_implicit;

      std::vector<uint8_t> m_msg_buffer;

};

}  // namespace Botan

#endif