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/*
* XMSS Index Registry
* A registry for XMSS private keys, keeps track of the leaf index for
* independend copies of the same key.
* (C) 2016 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
**/
#include <botan/internal/xmss_index_registry.h>
#include <botan/hash.h>
#include <limits>
namespace Botan {
const std::string XMSS_Index_Registry::m_index_hash_function = "SHA-256";
uint64_t XMSS_Index_Registry::make_key_id(
const secure_vector<uint8_t>& private_seed,
const secure_vector<uint8_t>& prf) const
{
std::unique_ptr<HashFunction> hash =
HashFunction::create(m_index_hash_function);
BOTAN_ASSERT(hash != nullptr, "XMSS_Index_Registry requires SHA-256");
hash->update(private_seed);
hash->update(prf);
secure_vector<uint8_t> result = hash->final();
uint64_t key_id = 0;
for(size_t i = 0; i < sizeof(key_id); i++)
{
key_id = ((key_id << 8) | result[i]);
}
return key_id;
}
std::shared_ptr<Atomic<size_t>>
XMSS_Index_Registry::get(const secure_vector<uint8_t>& private_seed,
const secure_vector<uint8_t>& prf)
{
size_t pos = get(make_key_id(private_seed, prf));
if(pos < std::numeric_limits<size_t>::max())
{
return m_leaf_indices[pos];
}
else
{
return m_leaf_indices[add(make_key_id(private_seed, prf))];
}
}
size_t XMSS_Index_Registry::get(uint64_t id) const
{
for(size_t i = 0; i < m_key_ids.size(); i++)
{
if(m_key_ids[i] == id)
{
return i;
}
}
return std::numeric_limits<size_t>::max();
}
size_t XMSS_Index_Registry::add(uint64_t id, size_t last_unused)
{
lock_guard_type<mutex_type> lock(m_mutex);
size_t pos = get(id);
if(pos < m_key_ids.size())
{
if(last_unused > *(m_leaf_indices[pos]))
{
m_leaf_indices[pos] = std::make_shared<Atomic<size_t>>(last_unused);
}
return pos;
}
m_key_ids.push_back(id);
m_leaf_indices.push_back(std::make_shared<Atomic<size_t>>(last_unused));
return m_key_ids.size() - 1;
}
}