/**

* (C) 2018 Jack Lloyd

* (C) 2018 Ribose Inc

*

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

*/

#ifndef BOTAN_SCRYPT_H_

#define BOTAN_SCRYPT_H_

#include <botan/pwdhash.h>

//BOTAN_FUTURE_INTERNAL_HEADER(scrypt.h)

namespace Botan {

/**

* Scrypt key derivation function (RFC 7914)

*/

class BOTAN_PUBLIC_API(2,8) Scrypt final : public PasswordHash

   {

   public:

      Scrypt(size_t N, size_t r, size_t p);

      Scrypt(const Scrypt& other) = default;

      Scrypt& operator=(const Scrypt&) = default;

      /**

      * Derive a new key under the current Scrypt parameter set

      */

      void derive_key(uint8_t out[], size_t out_len,

                      const char* password, size_t password_len,

                      const uint8_t salt[], size_t salt_len) const override;

      std::string to_string() const override;

      size_t N() const { return m_N; }

      size_t r() const { return m_r; }

      size_t p() const { return m_p; }

      size_t iterations() const override { return r(); }

      size_t parallelism() const override { return p(); }

      size_t memory_param() const override { return N(); }

      size_t total_memory_usage() const override;

   private:

      size_t m_N, m_r, m_p;

   };

class BOTAN_PUBLIC_API(2,8) Scrypt_Family final : public PasswordHashFamily

   {

   public:

      std::string name() const override;

      std::unique_ptr<PasswordHash> tune(size_t output_length,

                                         std::chrono::milliseconds msec,

                                         size_t max_memory) const override;

      std::unique_ptr<PasswordHash> default_params() const override;

      std::unique_ptr<PasswordHash> from_iterations(size_t iter) const override;

      std::unique_ptr<PasswordHash> from_params(

         size_t N, size_t r, size_t p) const override;

   };

/**

* Scrypt key derivation function (RFC 7914)

*

* @param output the output will be placed here

* @param output_len length of output

* @param password the user password

* @param password_len length of password

* @param salt the salt

* @param salt_len length of salt

* @param N the CPU/Memory cost parameter, must be power of 2

* @param r the block size parameter

* @param p the parallelization parameter

*

* Suitable parameters for most uses would be N = 32768, r = 8, p = 1

*

* Scrypt uses approximately (p + N + 1) * 128 * r bytes of memory

*/

void BOTAN_PUBLIC_API(2,8) scrypt(uint8_t output[], size_t output_len,

                                  const char* password, size_t password_len,

                                  const uint8_t salt[], size_t salt_len,

                                  size_t N, size_t r, size_t p);

/**

* Scrypt key derivation function (RFC 7914)

* Before 2.8 this function was the primary interface for scrypt

*

* @param output the output will be placed here

* @param output_len length of output

* @param password the user password

* @param salt the salt

* @param salt_len length of salt

* @param N the CPU/Memory cost parameter, must be power of 2

* @param r the block size parameter

* @param p the parallelization parameter

*

* Suitable parameters for most uses would be N = 32768, r = 8, p = 1

*

* Scrypt uses approximately (p + N + 1) * 128 * r bytes of memory

*/

inline void scrypt(uint8_t output[], size_t output_len,

                   const std::string& password,

                   const uint8_t salt[], size_t salt_len,

                   size_t N, size_t r, size_t p)

   {

   return scrypt(output, output_len,

                 password.c_str(), password.size(),

                 salt, salt_len,

                 N, r, p);

   }

inline size_t scrypt_memory_usage(size_t N, size_t r, size_t p)

   {

   return 128 * r * (N + p);

   }

}

#endif