/*

* KDF1

* (C) 1999-2007 Jack Lloyd

* (C) 2024      René Meusel, Rohde & Schwarz Cybersecurity

*

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

*/

#include <botan/internal/kdf1.h>

#include <botan/exceptn.h>

#include <botan/mem_ops.h>

#include <botan/internal/fmt.h>

namespace Botan {

std::string KDF1::name() const {

   return fmt("KDF1({})", m_hash->name());

}

std::unique_ptr<KDF> KDF1::new_object() const {

   return std::make_unique<KDF1>(m_hash->new_object());

}

void KDF1::perform_kdf(std::span<uint8_t> key,

                       std::span<const uint8_t> secret,

                       std::span<const uint8_t> salt,

                       std::span<const uint8_t> label) const {

   if(key.empty()) {

      return;

   }

   const size_t hash_output_len = m_hash->output_length();

   BOTAN_ARG_CHECK(key.size() <= hash_output_len, "KDF1 maximum output length exceeeded");

   m_hash->update(secret);

   m_hash->update(label);

   m_hash->update(salt);

   if(key.size() == hash_output_len) {

      // In this case we can hash directly into the output buffer

      m_hash->final(key);

   } else {

      // Otherwise a copy is required

      const auto v = m_hash->final();

      copy_mem(key, std::span{v}.first(key.size()));

   }

}

}  // namespace Botan