/*

* KDF2

* (C) 1999-2007 Jack Lloyd

*

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

*/

#include <botan/kdf2.h>

namespace Botan {

size_t KDF2::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

   {

   uint32_t counter = 1;

   secure_vector<uint8_t> h;

   size_t offset = 0;

   while(offset != key_len && counter != 0)

      {

      m_hash->update(secret, secret_len);

      m_hash->update_be(counter++);

      m_hash->update(label, label_len);

      m_hash->update(salt, salt_len);

      m_hash->final(h);

      const size_t added = std::min(h.size(), key_len - offset);

      copy_mem(&key[offset], h.data(), added);

      offset += added;

      }

   return offset;

   }

}