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/**
* XMSS Index Registry
* (C) 2016 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
**/
#ifndef BOTAN_XMSS_INDEX_REGISTRY_H__
#define BOTAN_XMSS_INDEX_REGISTRY_H__
#include <stdint.h>
#include <cstddef>
#include <limits>
#include <memory>
#include <string>
#include <botan/hash.h>
#include <botan/secmem.h>
#include <botan/types.h>
#include <botan/atomic.h>
#include <botan/mutex.h>
namespace Botan {
/**
* A registry for XMSS private keys, keeps track of the leaf index for
* independend copies of the same key.
**/
class XMSS_Index_Registry
{
public:
XMSS_Index_Registry(const XMSS_Index_Registry&) = delete;
XMSS_Index_Registry& operator=(const XMSS_Index_Registry&) = delete;
/**
* Retrieves a handle to the process-wide unique XMSS index registry.
*
* @return Reference to unique XMSS index registry.
**/
static XMSS_Index_Registry& get_instance()
{
static XMSS_Index_Registry self;
return self;
}
/**
* Retrieves the last unused leaf index for the private key identified
* by private_seed and prf. The leaf index will be updated properly
* across independent copies of private_key.
*
* @param private_seed Part of the unique identifier for an
* XMSS_PrivateKey.
* @param prf Part of the unique identifier for an XMSS_PrivateKey.
*
* @return last unused leaf index for private_key.
**/
std::shared_ptr<Atomic<size_t>>
get(const secure_vector<byte>& private_seed,
const secure_vector<byte>& prf);
private:
XMSS_Index_Registry()
: m_key_ids(), m_leaf_indices(), m_mutex() {}
static const std::string m_index_hash_function;
/**
* Creates a unique 64-bit id for an XMSS_Private key, by interpreting
* the first 64-bit of HASH(PRIVATE_SEED || PRF) as 64 bit integer
* value.
*
* @return unique integral identifier for an XMSS private key.
**/
uint64_t make_key_id(const secure_vector<byte>& private_seed,
const secure_vector<byte>& prf) const;
/**
* Retrieves the index position of a key within the registry or
* max(size_t) if key has not been found.
*
* @param unique id of the XMSS private key (see make_key_id()).
*
* @return index position of key or max(size_t) if key not found.
**/
size_t get(uint64_t id) const;
/**
* If XMSS_PrivateKey identified by id is already registered, the
* position of the according registry entry is returned. If last_unused
* is bigger than the last unused index stored for the key identified by
* id the unused leaf index for this key is set to last_unused. If no key
* matching id is registed yet, an entry of id is added, with the last
* unused leaf index initialized to the value of last_unused.
*
* @last_unused Initial value for the last unused leaf index of the
* registered key.
*
* @return positon of leaf index registry entry for key identified
* by id.
**/
size_t add(uint64_t id, size_t last_unused = 0);
std::vector<uint64_t> m_key_ids;
std::vector<std::shared_ptr<Atomic<size_t>>> m_leaf_indices;
mutex_type m_mutex;
};
}
#endif
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