Botan  2.7.0
Crypto and TLS for C++11
xmss_index_registry.cpp
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1 /*
2  * XMSS Index Registry
3  * A registry for XMSS private keys, keeps track of the leaf index for
4  * independend copies of the same key.
5  * (C) 2016 Matthias Gierlings
6  *
7  * Botan is released under the Simplified BSD License (see license.txt)
8  **/
9 
10 #include <botan/xmss_index_registry.h>
11 #include <botan/hash.h>
12 #include <limits>
13 
14 namespace Botan {
15 
16 const std::string XMSS_Index_Registry::m_index_hash_function = "SHA-256";
17 
18 uint64_t XMSS_Index_Registry::make_key_id(
19  const secure_vector<uint8_t>& private_seed,
20  const secure_vector<uint8_t>& prf) const
21  {
22  std::unique_ptr<HashFunction> hash =
23  HashFunction::create(m_index_hash_function);
24  BOTAN_ASSERT(hash != nullptr, "XMSS_Index_Registry requires SHA-256");
25  hash->update(private_seed);
26  hash->update(prf);
27  secure_vector<uint8_t> result = hash->final();
28  uint64_t key_id = 0;
29  for(size_t i = 0; i < sizeof(key_id); i++)
30  {
31  key_id = ((key_id << 8) | result[i]);
32  }
33 
34  return key_id;
35  }
36 
37 std::shared_ptr<Atomic<size_t>>
39  const secure_vector<uint8_t>& prf)
40  {
41  size_t pos = get(make_key_id(private_seed, prf));
42 
43  if(pos < std::numeric_limits<size_t>::max())
44  {
45  return m_leaf_indices[pos];
46  }
47  else
48  {
49  return m_leaf_indices[add(make_key_id(private_seed, prf))];
50  }
51  }
52 
53 size_t XMSS_Index_Registry::get(uint64_t id) const
54  {
55  for(size_t i = 0; i < m_key_ids.size(); i++)
56  {
57  if(m_key_ids[i] == id)
58  {
59  return i;
60  }
61  }
62 
63  return std::numeric_limits<size_t>::max();
64  }
65 
66 size_t XMSS_Index_Registry::add(uint64_t id, size_t last_unused)
67  {
68  lock_guard_type<mutex_type> lock(m_mutex);
69  size_t pos = get(id);
70  if(pos < m_key_ids.size())
71  {
72  if(last_unused > *(m_leaf_indices[pos]))
73  {
74  m_leaf_indices[pos] = std::make_shared<Atomic<size_t>>(last_unused);
75  }
76  return pos;
77  }
78 
79  m_key_ids.push_back(id);
80  m_leaf_indices.push_back(std::make_shared<Atomic<size_t>>(last_unused));
81  return m_key_ids.size() - 1;
82  }
83 
84 }
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:43
static std::unique_ptr< HashFunction > create(const std::string &algo_spec, const std::string &provider="")
Definition: hash.cpp:106
std::shared_ptr< Atomic< size_t > > get(const secure_vector< uint8_t > &private_seed, const secure_vector< uint8_t > &prf)
Definition: alg_id.cpp:13
std::vector< T, secure_allocator< T > > secure_vector
Definition: secmem.h:88
MechanismType hash