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
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
/*
* ECDSA implemenation
* (C) 2007 Manuel Hartl, FlexSecure GmbH
* 2007 Falko Strenzke, FlexSecure GmbH
* 2008-2010,2015,2016 Jack Lloyd
* 2016 René Korthaus
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/ecdsa.h>
#include <botan/internal/pk_ops_impl.h>
#include <botan/keypair.h>
#include <botan/reducer.h>
#include <botan/emsa.h>
#if defined(BOTAN_HAS_RFC6979_GENERATOR)
#include <botan/rfc6979.h>
#endif
#if defined(BOTAN_HAS_OPENSSL)
#include <botan/internal/openssl.h>
#endif
namespace Botan {
bool ECDSA_PrivateKey::check_key(RandomNumberGenerator& rng,
bool strong) const
{
if(!public_point().on_the_curve())
return false;
if(!strong)
return true;
return KeyPair::signature_consistency_check(rng, *this, "EMSA1(SHA-256)");
}
namespace {
/**
* ECDSA signature operation
*/
class ECDSA_Signature_Operation : public PK_Ops::Signature_with_EMSA
{
public:
ECDSA_Signature_Operation(const ECDSA_PrivateKey& ecdsa,
const std::string& emsa) :
PK_Ops::Signature_with_EMSA(emsa),
m_order(ecdsa.domain().get_order()),
m_base_point(ecdsa.domain().get_base_point(), m_order),
m_x(ecdsa.private_value()),
m_mod_order(m_order),
m_emsa(emsa)
{
}
secure_vector<byte> raw_sign(const byte msg[], size_t msg_len,
RandomNumberGenerator& rng) override;
size_t message_parts() const override { return 2; }
size_t message_part_size() const override { return m_order.bytes(); }
size_t max_input_bits() const override { return m_order.bits(); }
private:
const BigInt& m_order;
Blinded_Point_Multiply m_base_point;
const BigInt& m_x;
Modular_Reducer m_mod_order;
std::string m_emsa;
};
secure_vector<byte>
ECDSA_Signature_Operation::raw_sign(const byte msg[], size_t msg_len,
RandomNumberGenerator& rng)
{
const BigInt m(msg, msg_len);
#if defined(BOTAN_HAS_RFC6979_GENERATOR)
const BigInt k = generate_rfc6979_nonce(m_x, m_order, m, hash_for_emsa(m_emsa));
#else
const BigInt k = BigInt::random_integer(rng, 1, m_order);
#endif
const PointGFp k_times_P = m_base_point.blinded_multiply(k, rng);
const BigInt r = m_mod_order.reduce(k_times_P.get_affine_x());
const BigInt s = m_mod_order.multiply(inverse_mod(k, m_order), mul_add(m_x, r, m));
// With overwhelming probability, a bug rather than actual zero r/s
BOTAN_ASSERT(s != 0, "invalid s");
BOTAN_ASSERT(r != 0, "invalid r");
return BigInt::encode_fixed_length_int_pair(r, s, m_order.bytes());
}
/**
* ECDSA verification operation
*/
class ECDSA_Verification_Operation : public PK_Ops::Verification_with_EMSA
{
public:
ECDSA_Verification_Operation(const ECDSA_PublicKey& ecdsa,
const std::string& emsa) :
PK_Ops::Verification_with_EMSA(emsa),
m_base_point(ecdsa.domain().get_base_point()),
m_public_point(ecdsa.public_point()),
m_order(ecdsa.domain().get_order()),
m_mod_order(m_order)
{
//m_public_point.precompute_multiples();
}
size_t message_parts() const override { return 2; }
size_t message_part_size() const override { return m_order.bytes(); }
size_t max_input_bits() const override { return m_order.bits(); }
bool with_recovery() const override { return false; }
bool verify(const byte msg[], size_t msg_len,
const byte sig[], size_t sig_len) override;
private:
const PointGFp& m_base_point;
const PointGFp& m_public_point;
const BigInt& m_order;
// FIXME: should be offered by curve
Modular_Reducer m_mod_order;
};
bool ECDSA_Verification_Operation::verify(const byte msg[], size_t msg_len,
const byte sig[], size_t sig_len)
{
if(sig_len != m_order.bytes()*2)
return false;
BigInt e(msg, msg_len);
BigInt r(sig, sig_len / 2);
BigInt s(sig + sig_len / 2, sig_len / 2);
if(r <= 0 || r >= m_order || s <= 0 || s >= m_order)
return false;
BigInt w = inverse_mod(s, m_order);
const BigInt u1 = m_mod_order.reduce(e * w);
const BigInt u2 = m_mod_order.reduce(r * w);
const PointGFp R = multi_exponentiate(m_base_point, u1, m_public_point, u2);
if(R.is_zero())
return false;
const BigInt v = m_mod_order.reduce(R.get_affine_x());
return (v == r);
}
}
std::unique_ptr<PK_Ops::Verification>
ECDSA_PublicKey::create_verification_op(const std::string& params,
const std::string& provider) const
{
#if defined(BOTAN_HAS_OPENSSL)
if(provider == "openssl" || provider.empty())
{
try
{
return make_openssl_ecdsa_ver_op(*this, params);
}
catch(Lookup_Error& e)
{
if(provider == "openssl")
throw;
}
}
#endif
if(provider == "base" || provider.empty())
return std::unique_ptr<PK_Ops::Verification>(new ECDSA_Verification_Operation(*this, params));
throw Provider_Not_Found(algo_name(), provider);
}
std::unique_ptr<PK_Ops::Signature>
ECDSA_PrivateKey::create_signature_op(RandomNumberGenerator& /*rng*/,
const std::string& params,
const std::string& provider) const
{
#if defined(BOTAN_HAS_OPENSSL)
if(provider == "openssl" || provider.empty())
{
try
{
return make_openssl_ecdsa_sig_op(*this, params);
}
catch(Lookup_Error& e)
{
if(provider == "openssl")
throw;
}
}
#endif
if(provider == "base" || provider.empty())
return std::unique_ptr<PK_Ops::Signature>(new ECDSA_Signature_Operation(*this, params));
throw Provider_Not_Found(algo_name(), provider);
}
}
|
