/*

* KDF defined in NIST SP 800-56c

* (C) 2016 Kai Michaelis

*

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

*/

#ifndef BOTAN_SP800_56C_H_

#define BOTAN_SP800_56C_H_

#include <botan/kdf.h>

#include <botan/mac.h>

namespace Botan {

/**

 * NIST SP 800-56C KDF

 */

class SP800_56C final : public KDF

   {

   public:

      std::string name() const override { return "SP800-56C(" + m_prf->name() + ")"; }

      KDF* clone() const override { return new SP800_56C(m_prf->clone(), m_exp->clone()); }

      /**

      * Derive a key using the SP800-56C KDF.

      *

      * The implementation hard codes the context value for the

      * expansion step to the empty string.

      *

      * @param key derived keying material K_M

      * @param key_len the desired output length in bytes

      * @param secret shared secret Z

      * @param secret_len size of Z in bytes

      * @param salt salt s of the extraction step

      * @param salt_len size of s in bytes

      * @param label label for the expansion step

      * @param label_len size of label in bytes

      *

      * @throws Invalid_Argument key_len > 2^32

      */

      size_t kdf(uint8_t key[], size_t key_len,

                 const uint8_t secret[], size_t secret_len,

                 const uint8_t salt[], size_t salt_len,

                 const uint8_t label[], size_t label_len) const override;

      /**

      * @param mac MAC algorithm used for randomness extraction

      * @param exp KDF used for key expansion

      */

      SP800_56C(MessageAuthenticationCode* mac, KDF* exp) : m_prf(mac), m_exp(exp) {}

   private:

      std::unique_ptr<MessageAuthenticationCode> m_prf;

      std::unique_ptr<KDF> m_exp;

   };

}

#endif