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
|
/*
* ECDSA implemenation
* (C) 2007 Manuel Hartl, FlexSecure GmbH
* 2007 Falko Strenzke, FlexSecure GmbH
* 2008-2010,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/internal/pk_utils.h>
#include <botan/ecdsa.h>
#include <botan/keypair.h>
#include <botan/rfc6979.h>
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-1)");
}
namespace {
/**
* ECDSA signature operation
*/
class ECDSA_Signature_Operation : public PK_Ops::Signature_with_EMSA
{
public:
typedef ECDSA_PrivateKey Key_Type;
ECDSA_Signature_Operation(const ECDSA_PrivateKey& ecdsa,
const std::string& emsa) :
PK_Ops::Signature_with_EMSA(emsa),
base_point(ecdsa.domain().get_base_point()),
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_hash(hash_for_deterministic_signature(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 PointGFp& base_point;
const BigInt& m_order;
Blinded_Point_Multiply m_base_point;
const BigInt& m_x;
Modular_Reducer m_mod_order;
std::string m_hash;
};
secure_vector<byte>
ECDSA_Signature_Operation::raw_sign(const byte msg[], size_t msg_len,
RandomNumberGenerator& rng)
{
const BigInt m(msg, msg_len);
const BigInt k = generate_rfc6979_nonce(m_x, m_order, m, m_hash);
//const PointGFp k_times_P = base_point * k;
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");
secure_vector<byte> output(2*m_order.bytes());
r.binary_encode(&output[output.size() / 2 - r.bytes()]);
s.binary_encode(&output[output.size() - s.bytes()]);
return output;
}
/**
* ECDSA verification operation
*/
class ECDSA_Verification_Operation : public PK_Ops::Verification_with_EMSA
{
public:
typedef ECDSA_PublicKey Key_Type;
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);
}
BOTAN_REGISTER_PK_SIGNATURE_OP("ECDSA", ECDSA_Signature_Operation);
BOTAN_REGISTER_PK_VERIFY_OP("ECDSA", ECDSA_Verification_Operation);
}
}
|
