1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
/*
* XMSS Private Key
* An XMSS: Extended Hash-Based Siganture private key.
* The XMSS private key does not support the X509 and PKCS7 standard. Instead
* the raw format described in [1] is used.
*
* [1] XMSS: Extended Hash-Based Signatures,
* draft-itrf-cfrg-xmss-hash-based-signatures-06
* Release: July 2016.
* https://datatracker.ietf.org/doc/
* draft-irtf-cfrg-xmss-hash-based-signatures/?include_text=1
*
* (C) 2016 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
**/
#include <botan/xmss_privatekey.h>
#include <botan/internal/xmss_signature_operation.h>
#include <cmath>
namespace Botan {
XMSS_PrivateKey::XMSS_PrivateKey(const secure_vector<uint8_t>& raw_key)
: XMSS_PublicKey(unlock(raw_key)),
XMSS_Common_Ops(XMSS_PublicKey::m_xmss_params.oid()),
m_wots_priv_key(m_wots_params.oid(), m_public_seed),
m_index_reg(XMSS_Index_Registry::get_instance())
{
BOTAN_ASSERT(sizeof(size_t) >= std::ceil(
static_cast<float>(XMSS_PublicKey::m_xmss_params.tree_height()) / 8.f),
"System type \"size_t\" not big enough to support"
" leaf index.");
if(raw_key.size() != size())
{
throw Integrity_Failure("Invalid XMSS private key size detected.");
}
// extract & copy unused leaf index from raw_key.
uint64_t unused_leaf = 0;
auto begin = (raw_key.begin() + XMSS_PublicKey::size());
auto end = raw_key.begin() + XMSS_PublicKey::size() + sizeof(uint64_t);
for(auto& i = begin; i != end; i++)
unused_leaf = ((unused_leaf << 8) | *i);
if(unused_leaf >= (1ull << (XMSS_PublicKey::m_xmss_params.tree_height() - 1)))
{
throw Integrity_Failure("XMSS private key leaf index out of "
"bounds.");
}
begin = end;
end = begin + XMSS_PublicKey::m_xmss_params.element_size();
m_prf.clear();
m_prf.reserve(XMSS_PublicKey::m_xmss_params.element_size());
std::copy(begin, end, std::back_inserter(m_prf));
begin = end;
end = begin + m_wots_params.element_size();
m_wots_priv_key.set_private_seed(secure_vector<uint8_t>(begin, end));
set_unused_leaf_index(static_cast<size_t>(unused_leaf));
}
XMSS_PrivateKey::XMSS_PrivateKey(
XMSS_Parameters::xmss_algorithm_t xmss_algo_id,
RandomNumberGenerator& rng)
: XMSS_PublicKey(xmss_algo_id, rng),
XMSS_Common_Ops(xmss_algo_id),
m_wots_priv_key(XMSS_PublicKey::m_xmss_params.ots_oid(),
public_seed(),
rng),
m_prf(rng.random_vec(XMSS_PublicKey::m_xmss_params.element_size())),
m_index_reg(XMSS_Index_Registry::get_instance())
{
XMSS_Address adrs;
set_root(tree_hash(0,
XMSS_PublicKey::m_xmss_params.tree_height(),
adrs));
}
secure_vector<uint8_t>
XMSS_PrivateKey::tree_hash(size_t start_idx,
size_t target_node_height,
XMSS_Address& adrs)
{
const secure_vector<uint8_t>& seed = this->public_seed();
BOTAN_ASSERT((start_idx % (1 << target_node_height)) == 0,
"Start index must be divisible by 2^{target node height}.");
std::vector<secure_vector<uint8_t>> nodes(
XMSS_PublicKey::m_xmss_params.tree_height() + 1,
secure_vector<uint8_t>(XMSS_PublicKey::m_xmss_params.element_size()));
// node stack, holds all nodes on stack and one extra "pending" node. This
// temporary node referred to as "node" in the XMSS standard document stays
// a pending element, meaning it is not regarded as element on the stack
// until level is increased.
std::vector<uint8_t> node_levels(XMSS_PublicKey::m_xmss_params.tree_height() + 1);
uint8_t level = 0;
XMSS_WOTS_PublicKey pk(m_wots_priv_key.wots_parameters().oid(), seed);
size_t last_idx = static_cast<size_t>(1 << target_node_height) + start_idx;
for(size_t i = start_idx; i < last_idx; i++)
{
adrs.set_type(XMSS_Address::Type::OTS_Hash_Address);
adrs.set_ots_address(i);
this->wots_private_key().generate_public_key(
pk,
// getWOTS_SK(SK, s + i), reference implementation uses adrs
// instead of zero padded index s + i.
this->wots_private_key()[adrs],
adrs);
adrs.set_type(XMSS_Address::Type::LTree_Address);
adrs.set_ltree_address(i);
create_l_tree(nodes[level], pk, adrs, seed);
node_levels[level] = 0;
adrs.set_type(XMSS_Address::Type::Hash_Tree_Address);
adrs.set_tree_height(0);
adrs.set_tree_index(i);
while(level > 0 && node_levels[level] ==
node_levels[level - 1])
{
adrs.set_tree_index(((adrs.get_tree_index() - 1) >> 1));
randomize_tree_hash(nodes[level - 1],
nodes[level - 1],
nodes[level],
adrs,
seed);
node_levels[level - 1]++;
level--; //Pop stack top element
adrs.set_tree_height(adrs.get_tree_height() + 1);
}
level++; //push temporary node to stack
}
return nodes[level - 1];
}
std::shared_ptr<Atomic<size_t>>
XMSS_PrivateKey::recover_global_leaf_index() const
{
BOTAN_ASSERT(m_wots_priv_key.private_seed().size() ==
XMSS_PublicKey::m_xmss_params.element_size() &&
m_prf.size() == XMSS_PublicKey::m_xmss_params.element_size(),
"Trying to retrieve index for partially initialized "
"key.");
return m_index_reg.get(m_wots_priv_key.private_seed(),
m_prf);
}
secure_vector<uint8_t> XMSS_PrivateKey::raw_private_key() const
{
std::vector<uint8_t> pk { raw_public_key() };
secure_vector<uint8_t> result(pk.begin(), pk.end());
result.reserve(size());
for(int i = 7; i >= 0; i--)
{
result.push_back(
static_cast<uint8_t>(
static_cast<uint64_t>(unused_leaf_index()) >> 8 * i));
}
std::copy(m_prf.begin(), m_prf.end(), std::back_inserter(result));
std::copy(m_wots_priv_key.private_seed().begin(),
m_wots_priv_key.private_seed().end(),
std::back_inserter(result));
return result;
}
std::unique_ptr<PK_Ops::Signature>
XMSS_PrivateKey::create_signature_op(RandomNumberGenerator&,
const std::string&,
const std::string& provider) const
{
if(provider == "base" || provider.empty())
return std::unique_ptr<PK_Ops::Signature>(
new XMSS_Signature_Operation(*this));
throw Provider_Not_Found(algo_name(), provider);
}
}
|
